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Timleech
09-16-2010, 06:37 PM
Well into the job of getting a 1960s Kelvin marine diesel back into service, we made a nasty discovery yesterday.
The decision had been made to replace all the main bearing shells, as inspection of the two end bearings showed significant though not really bad wear to the shells, and there had been an issue with the oil filtration (ie there hadn't been any for some time!) in the past.
This can be done in situ, through the crankcase doors, but it's not a five minute job and they can't all be done at once. The nuts have a tightening torque of 500 lbft, working through a little 'window' with a 90 degree spanner and at ankle height. Loads of fun!
Anyway, nearly had them all done yesterday apart from final tightening when I found that the centre main had spun in its housing, and then discovered that the bearing cap was distorted, the sides had come in by about 15 thou. This was the one I least expected to be trouble, as it's the first in line for the oil feed.
A problem like that would be dealt with in a vehicle sized engine with a complete strip down, then cutting down the bearing cap and reboring. That's simply not an option in this case, with a 3.5 ton engine in a restricted engine room and a lot of work already done. Anything I did had to be done with crankcase and crankshaft in place.
The options seemed to be to machine the cap away from the engine and probably have awkward hand fitting to do to refit properly, or to 'straighten' it out. The second option seemed the better bet if it would work, so here's what I did:-

The bearing housings have a nominal bore of 5.25". I took a piece of 6" CI bar, that's the nearest I had to hand, and turned it to 5.258" DIA. This was a guessed size, with some help from Sir John on the guesswork, as to how much oversize it needed to be:-

http://i559.photobucket.com/albums/ss38/Timleech_2009/mersey2010/Kelvin/P1000604.jpg

Then the bearing cap was heated to about 500C

http://i559.photobucket.com/albums/ss38/Timleech_2009/mersey2010/Kelvin/P1000607.jpg

I used an infrared thermometer to check that the heating was reasonably uniform.

Then the idea was to press the CI former into the housing and let it cool.

http://i559.photobucket.com/albums/ss38/Timleech_2009/mersey2010/Kelvin/P1000610.jpg

In fact, the heating expanded the cap sufficient that the former just dropped into place, the press wasn't really needed.

Anyway, after allowing to cool and releasing the cap from the former, it was still about 6 or 7 thou undersize at the opening, so I repeated the process with a strip of 4 thou shim under the former. Result, the cap is now within a thou of an undamaged cap so should be OK.

The real test comes tomorrow, when I'll try a test assembly with some plastigage strips to check clearances.

Tim

Guido
09-16-2010, 06:52 PM
Resourceful----------My bet's on you.

--G

winchman
09-16-2010, 07:40 PM
It seems like the mating surfaces of the cap would be at a slight angle to each other after the fix. Have you checked that? Is it an issue?

What kind of jaws are those on your lathe chuck? I've never seen any with so much grip area.

Timleech
09-16-2010, 07:53 PM
It seems like the mating surfaces of the cap would be at a slight angle to each other after the fix. Have you checked that? Is it an issue?

What kind of jaws are those on your lathe chuck? I've never seen any with so much grip area.

The cap should be pretty much back where it started, the aim was to remove distortion and get it back as close as possible to its original shape. The faces might have been at a slight angle before doing the work, never thought to check.

The jaws are a fairly standard form of soft jaw for serrated-jaw chucks, I picked up a bucket full of them, used but plenty of life still in them, at an auction. I took a chance, and they needed only very slight modification to fit my chuck. Really made for power chucks but very handy.

See
http://www.thame-eng.com/DiamondSerratedSoftJaws.pdf

Tim

Carld
09-16-2010, 09:09 PM
If the main bearing shells spun in the bore you still have a problem. I have never seen what your doing work for very long. The problem is the clearances in the main bore are oversize and distorted after the shells spin and there may be metal buildup on the bearing bore in the block.

Someone will end up pulling the engine and doing it right.

If the faces your talking about are the surfaces that mate up to the block they are perfectly flat as is the block. The way to do a line bore is to machine off the surfaces that mate with the block and then set the boring bar up and machine the cap bore to match the block bore. You have to be very careful to not cut the block part of the bore.

JRouche
09-17-2010, 12:45 AM
I think its a pretty cool way of getting the engine back to power. I was trying to visualize how you do it. Ive only worked on car engines and I have yanked the crank out of the engine while it was still in the car, but never did open heart surgery like you are doing..

How do you get the top shell in, and out? Do you remove all the caps then lower the crank to the pan? Also, with the cap sprung so much were the bolts very tight when removing them? Or do you use studs. Seems if the cap was bent in a lil the bolts would be hard to line up in the bolt holes. Unless the cap bolt holes are large enough.

Anyway, I think the engine will be fine. Certainly a whole lot better off than she was. JR

Timleech
09-17-2010, 04:02 AM
I think its a pretty cool way of getting the engine back to power. I was trying to visualize how you do it. Ive only worked on car engines and I have yanked the crank out of the engine while it was still in the car, but never did open heart surgery like you are doing..

How do you get the top shell in, and out? Do you remove all the caps then lower the crank to the pan? Also, with the cap sprung so much were the bolts very tight when removing them? Or do you use studs. Seems if the cap was bent in a lil the bolts would be hard to line up in the bolt holes. Unless the cap bolt holes are large enough.

Anyway, I think the engine will be fine. Certainly a whole lot better off than she was. JR

The top shell is removed by barring the crank around, with a suitably folded split pin or similar in the crank oil hole. Reverse to replace, though finger pressure is just about enough to help the new shell in following the rotating crank.

The bearing caps are on studs, in fact the studs go right the way through from cylinder head to crankshaft. They're threaded into the crankcase, and also have nuts to hold the cylinder blocks in place. They're 1 1/8" BSF. They are 'necked' below the threads where they pass through the bearing caps, but yes this cap was a little tighter than the others to remove.

Tim

Timleech
09-17-2010, 04:08 AM
If the main bearing shells spun in the bore you still have a problem. I have never seen what your doing work for very long. The problem is the clearances in the main bore are oversize and distorted after the shells spin and there may be metal buildup on the bearing bore in the block.

Someone will end up pulling the engine and doing it right.

If the faces your talking about are the surfaces that mate up to the block they are perfectly flat as is the block. The way to do a line bore is to machine off the surfaces that mate with the block and then set the boring bar up and machine the cap bore to match the block bore. You have to be very careful to not cut the block part of the bore.

That isn't an option, certainly not at present. Priority is to get it up & running.
If it comes to pulling the engine and that scale of work is needed, at that stage it'll make more sense to have another engine ready to fit as replacement. I'm well aware of your last part about the line boring, I did mention it in my original post. It's never going to happen with this engine, too big & too expensive.

EDIT to add :-

Wear to the inside of the cap appears to be no more than a slight polishing. As said, I'll be checking clearances with Plastigage strips before final assembly.

Re the soft jaws, I had them set up for this job, for a different engine:-

http://i559.photobucket.com/albums/ss38/Timleech_2009/P1000600.jpg

They're ideal for this sort of thing, actually a water pump drive gear. A new pump was being fitted, but it has a 25mm shaft while the original had a 1" shaft.. Bore out, sleeve, bore again, broach keyway. Sleeve held with Loctite retainer plus three M5 screw dowels at 120 degrees along the interface, also loctited. Pic shows reaming to size with adjustable floating reamer.

The outer recess in the jaws was then easily adaptable to hold the piece of 6" CI bar,which had very little spare length.

Tim

Carld
09-17-2010, 09:54 AM
If it spun enough to damage the main cap it damaged the upper part of the main bore.

Good luck.

I probably still have the short bolts I ground the heads down on to roll main shells out and in doing in the chassis overhauls laying under the truck with the old black oil dripping all over the fender cover I layed on me from my neck to below my waist. That's one job I always hated.

The Fixer
09-17-2010, 11:55 AM
I'm with you on this one Carld, unless he has a big bag of horseshoes .......
I can really appreciate what/why OP is trying this and have seen similar things done over the years but generally with less than great outcomes. While this may 'last' for a while it won't have the longevity of a proper repair. The fact that this one (of the five?) failed in the first place tells me there is something else going on that needs to be scienced out. The spun bearing is a symptom not the 'problem'.
Of course I could be wrong, so here's hopin it works out for you and I like your method(s) and creative thinking to problem solve!

Carld
09-17-2010, 05:28 PM
One does what one has to do to get the problem down the road/river to the next mechanic.

The Artful Bodger
09-17-2010, 05:29 PM
I do not see why the intended repair should not give satisfaction...

The lower shell is locked to the cap (?) and that is what stops the upper shell from rotating. If the bearing shell has removed material such that the upper shell has excess clearance I am sure there are all sorts of filler materiald that could be used.

What is the likely cause of failure of repairs like this is that the oil feed has become blocked and the new shell gets starved of oil leading to the predicted premature failure. A good dose of compressed air in the oil gallery may avoid this.

Just my opinion.

Timleech
09-17-2010, 06:41 PM
I am convinced that no significant material has been lost from the cap, it's simply a distortion issue. The new top shell slid into place with exactly the same level of ease/difficulty as all the others. I've measured the crank journal as best I can, good old fashioned firm joint calipers were the only option given the limited access and it's within a thou or so of original (and it is 42 years old). The maker's specs allow for a bearing clearance of up to 14 thou before work is needed, from a new clearance of 4.5 to 7 thou. I did need to polish a small amount of bearing material off it, that was before measuring. There is one simple score line on the crank, it's otherwise looking good.
I've discussed this with my local friendly engine reconditioner, in case he had tried anything similar or had any better ideas. He hadn't, but has seen the cap and has approved of my methods. Incidentally he has a big V8 Cummins generator engine in the shop at the moment for line boring after exactly the same problem. It's a well established and respected outfit.
Don't forget this is not some highly-stressed vehicle engine but one essentially designed for long hours (and dare I say poor maintenance!) in a fishing boat, so relatively 'over engineered' by modern standards, and with a max speed of 1000 rpm and expected many tens of thousands of hours between major overhauls.
I know it's not going to be like new, but wouldn't be putting the work in if I wasn't confident of a useful result.
As to the cause, there is evidence that there's been water in the oil and as already remarked the filtration had been inadvertently disabled. How long for, we'll never know, but I suspect quite a long time.

Tim

DICKEYBIRD
09-17-2010, 10:37 PM
Hey Tim, when you get 'er back together and take 'er out on a test run; cruise on over t'other side of the pond. When you see the east coast, ignore it and and swing down south around Florida and back up the Gulf and into the mighty Mississippi. Head north but watch out for sandbars; she's a bit low this time of year. When you go under the old bridges and see a Pyramid on your right, that'll be Memphis. (TN, not Egypt)

Gimme a shout on the dog n' bone and I'll meet you at the Rendezvous (less than a mile from the riverbank.) I'll buy you all the Memphis BBQ ribs & beer you can scarf down.:)

I have faith in yer engine repair so when we're finished eatin' ribs, I'll hop on board and you can show me how good she runs on the way back home. She ought'a be good & broke in by then. By the time we get there, I'll be hungry again (I'm always hungry.) Harry Ramsden's'll do I reckon.:D

Timleech
09-18-2010, 05:53 AM
Hey Tim, when you get 'er back together and take 'er out on a test run; cruise on over t'other side of the pond. When you see the east coast, ignore it and and swing down south around Florida and back up the Gulf and into the mighty Mississippi. Head north but watch out for sandbars; she's a bit low this time of year. When you go under the old bridges and see a Pyramid on your right, that'll be Memphis. (TN, not Egypt)

Gimme a shout on the dog n' bone and I'll meet you at the Rendezvous (less than a mile from the riverbank.) I'll buy you all the Memphis BBQ ribs & beer you can scarf down.:)

I have faith in yer engine repair so when we're finished eatin' ribs, I'll hop on board and you can show me how good she runs on the way back home. She ought'a be good & broke in by then. By the time we get there, I'll be hungry again (I'm always hungry.) Harry Ramsden's'll do I reckon.:D


Thanks for the tempting offer, Dickey ;)
Sadly it's not my boat, anyway it's a little dry cargo barge with some coasting capability but the Big Pond might be a bit much for it.

Incidentally this is the engine:-

http://www.sky-net.org.uk/kelvin/diesel/t_range/t6/index.html

Cheers
Tim

A.K. Boomer
09-18-2010, 09:05 AM
If it spun enough to damage the main cap it damaged the upper part of the main bore.

Good luck.




Not necessarily, and in fact far less likely --- crank pressures transmit load in the order in which its received, there are two real forms of load --- compression and combustion - BOTH load the crank INTO the cap whilst the upper block bearing actually GAINS clearance. My big concern is not excessive clearance - being a single main in the middle it will run for decades with that, its metal transfer from the bearing backing to the bore, If the bottom does not have it then its unlikely the top will, but if there's any at all then its a recipe for disaster ---- if the new bearings don't have enough clearance then he needs to make them have enough even if on the sloppy side,
He can either remove a little babbit material or assemble the cap and torque it down and mildly brass hammer it into the crank - this will seat the bearing backs into the highs without fanning out the cap again, Also - If the bearings are pinned he can also install .0015" size shims for clearance on the cap --- run engine for an hour, if that don't do it then a day or even a week then remove shims completely -- let the engine do the work and whip the crank into the bores and seat the bearing backs into the highs.

Mains are so forgiving (but not with being tight) ----- its connecting rods that have to be right on the money without being too loose or tight.

Im with Timeleech on this one and in fact that's what separates a mechanic from a master mechanic --- the master throws the book away and writes his own rules, This is the only way one knows how to save his ass in a jam like this ------- the following advice I just gave is from such incidences where iv had to shift on the fly and come up with the goods and avoid costly crank/transmission removal and not have the vehicle come back either...

Mains don't scare me - not at all - give them some room to breath that's all - believe me the crank does not mind flexing a few thou...
One semi-loose main won't even put a dent in oil pressure, Mains have it easy esp. a main in the middle as it has guided support on either side of it, give it clearance and it will live...

Timleech
09-18-2010, 01:35 PM
Mains don't scare me - not at all - give them some room to breath that's all - believe me the crank does not mind flexing a few thou...


I nipped the cap up yesterday, with new shells and a strip of Plastigauge at about 4 o'clock. It came out showing 7 thou clearance ;)

Tim

Carld
09-18-2010, 02:12 PM
Well, in about 17 years as a diesel mechanic I have never seen a spun main bearing last long if it wasn't line bored. Bearing caps don't get deformed from normal use. I approve of his straightening method but the only way to know if the bore is out of round or damaged is to run a bore test ring through it without the crank. He didn't mention if the cap was discolored and that would be an issue. There is a lot we don't know without seeing it.

A "mechanic" may try to shade tree the repair but I seriously doubt a "Master Mechanic", that is a real "Master Mechanic" would do that remembering his reputation rests on his work and it's quality. I know a few diesel Master Mechanics and I can tell you they would never do what he is doing unless it was to get it to where the correct repairs could be made. The problem is, if the engine runs and gets to the next port or truck stop the owner, driver or captain will keep on using it and when it fails the last mechanic will get the blame be he Master Mechanic or just a "lowly mechanic".

Remember that YOUR the one that made reference to mechanic vs master mechanic, not me. I am just pointing out the error of your thought of how they compare.

Now all this discussion about the serviceability of this repair depends on the reliable description of the damage. The problem is he can't see what the main bore looks like above the crank with the crank in place. He has to ASSUME there is no damage and buildup in the top bore area.

The kicker is how much the bearing spun and how long it was oil starved and is there metal in the oil hole in the block. He or no one else knows that. Any time you attempt a repair like that your taking a big gamble and with engines in large boats almost always being difficult to remove it may be worth a gamble. I never was on a crew that worked on the large river boats our distributor worked on. I know some times they had to carry the engine out of the engine room in pieces all the way down to the block and crank and then hand carry the crank and block out of the engine room. In one case a boat with dual Cummins VT903's they had to torch the rear deck out and then lift the engines out with a crane. Boats are hell to work on and I never wanted any part of them, the trucks were bad enough for me. I never have understood why they build the boat around the engine with no way to remove them in many cases.

I looked at the link and it's a nice looking engine and big. If he is lucky and there is no damage to the top bore, build up or wear or distortion it may work and it's a gamble and he knows and admits it. Time will tell but you can be assured he will get some blame when and if it fails. It just works that way, in their mind they always blame the last mechanic and tell everyone about it.

Been there, seen it and dealt with it. There is nothing like a pissed off owner/driver when they come back for warranty.

wierdscience
09-18-2010, 02:15 PM
Nice Job Tim,a good repair job is the one that works.

Timleech
09-18-2010, 02:57 PM
There is nothing like a pissed off owner/driver when they come back for warranty.

There will be no warranty. The owners are involved and know exactly what is being done, they know I'll do my best within the remit I was given.

The oil feed is via pipes from below, not through the block, cleaning them out is easy. The paint on the cap was a slightly darker shade than the rest, but my heating discoloured it a lot more. There's no discolouration of the seating in the cap.
The shells are still smooth on the back.

Tim

clutch
09-18-2010, 07:15 PM
So when you rotated the upper bearing into place around the crank, did you shine a light to see what sort of gap exists between the outside of the upper shell and the block?

Might give an idea visually of how wallered it is.

Clutch

Timleech
09-19-2010, 07:03 AM
So when you rotated the upper bearing into place around the crank, did you shine a light to see what sort of gap exists between the outside of the upper shell and the block?

Might give an idea visually of how wallered it is.

Clutch

No gap, I'm confident there's no damage to the crankcase bore. There's none to the cap apart from the distortion, and the cap is what takes the load.

I started this thread just because I thought others might be interested in my method for reshaping the distorted cap, not interested in all the argument and negativity, the 'it'll never work!' stuff. I'm happy with what I've done and that the owners will soon be able to get their barge earning money.


Tim

mike4
09-19-2010, 07:50 AM
No gap, I'm confident there's no damage to the crankcase bore. There's none to the cap apart from the distortion, and the cap is what takes the load.

I started this thread just because I thought others might be interested in my method for reshaping the distorted cap, not interested in all the argument and negativity, the 'it'll never work!' stuff. I'm happy with what I've done and that the owners will soon be able to get their barge earning money.


Tim
I have had similar responses to "field repairs" of large dozers , which I have assisted friends with , like removing and replacing the final drive in a D9 which has to be moved before it goes under water .
It broke down in a river bed and was about 200klms or more from the nearest workshop.

We had the basics , 400amp welder, and a well kitted service vehicle.

We had limited room and couldnt get a crane anywhere near the dozer due to the terrain,a rough lifting frame was fabricated and the gears and shaft removed ,then the damaged shaft was ground with an angle grinder to "v" out where it had broken and a jig fabbed from angle to hold it as straight as possible , then welded by one operator while the other kept it heated with an oxy /acet torch .
Once welding was completed and the shaft had cooled enough to touch it was ground to size using a bearing a a guide to gauge the diameter .

Rough but it worked and the machine was reassembled and driven 9 miles back to camp and loaded onto a float before the water got too high .
Sorry no pics as it was 30 years ago .

The Caterpillar service people sounded exactly like some here , we did what we could with what we had in the time available , no furthe damage was caused to the machine .

When it was stripped down about a month later there was some slight marking where the bearing was seated but the shaft was straight enough to survive a months work without any discernable wear in the mating splines caused by our impossible to do in the field fix.

wierdscience
09-19-2010, 08:07 AM
I think some here don't realise this isn't the average automotive diesel engine.This is a large frame marine diesel,the oil flow is greater and the RPM is much lower.What Tim did will work fine,I have seen much less care taken in the same type repair.Try seeing the bearings set in Redhand epoxy and happily running years later.It's been done and worked well,relax.

Richard-TX
09-19-2010, 11:17 AM
No gap, I'm confident there's no damage to the crankcase bore. There's none to the cap apart from the distortion, and the cap is what takes the load.

I started this thread just because I thought others might be interested in my method for reshaping the distorted cap, not interested in all the argument and negativity, the 'it'll never work!' stuff. I'm happy with what I've done and that the owners will soon be able to get their barge earning money.


Tim

Tim,

Based on my experience with engines of that class (GM Locomotive and Marine engines) I believe your repair is a good one and one that will last. I also believe you did your due diligence in all aspects of the repair. Well done and thanks for the pictorial.

A.K. Boomer
09-19-2010, 11:23 AM
Well, in about 17 years as a diesel mechanic I have never seen a spun main bearing last long if it wasn't line bored. Bearing caps don't get deformed from normal use. I approve of his straightening method but the only way to know if the bore is out of round or damaged is to run a bore test ring through it without the crank. He didn't mention if the cap was discolored and that would be an issue. There is a lot we don't know without seeing it.

A "mechanic" may try to shade tree the repair but I seriously doubt a "Master Mechanic", that is a real "Master Mechanic" would do that remembering his reputation rests on his work and it's quality. I know a few diesel Master Mechanics and I can tell you they would never do what he is doing unless it was to get it to where the correct repairs could be made. The problem is, if the engine runs and gets to the next port or truck stop the owner, driver or captain will keep on using it and when it fails the last mechanic will get the blame be he Master Mechanic or just a "lowly mechanic".

Remember that YOUR the one that made reference to mechanic vs master mechanic, not me. I am just pointing out the error of your thought of how they compare.

Now all this discussion about the serviceability of this repair depends on the reliable description of the damage. The problem is he can't see what the main bore looks like above the crank with the crank in place. He has to ASSUME there is no damage and buildup in the top bore area.

The kicker is how much the bearing spun and how long it was oil starved and is there metal in the oil hole in the block. He or no one else knows that. Any time you attempt a repair like that your taking a big gamble and with engines in large boats almost always being difficult to remove it may be worth a gamble. I never was on a crew that worked on the large river boats our distributor worked on. I know some times they had to carry the engine out of the engine room in pieces all the way down to the block and crank and then hand carry the crank and block out of the engine room. In one case a boat with dual Cummins VT903's they had to torch the rear deck out and then lift the engines out with a crane. Boats are hell to work on and I never wanted any part of them, the trucks were bad enough for me. I never have understood why they build the boat around the engine with no way to remove them in many cases.

I looked at the link and it's a nice looking engine and big. If he is lucky and there is no damage to the top bore, build up or wear or distortion it may work and it's a gamble and he knows and admits it. Time will tell but you can be assured he will get some blame when and if it fails. It just works that way, in their mind they always blame the last mechanic and tell everyone about it.

Been there, seen it and dealt with it. There is nothing like a pissed off owner/driver when they come back for warranty.



Carld Not knocking you but you sound totally by the book, Like I stated earlier sometimes you have to throw the book away, Not everything is "cut and dry" And of course there's risk - there's even risk in doing it by the book, And in fact there are many times that I give my customers a plethora of options all having to do with what kind of risk vs money savings their after, because im word of mouth they here about all my successes while saving people a bundle - all while having so few of failures that if I do lose one here or there it pales in comparison to the hundreds saved,
Im not out to keep a perfect score at the expense of ALL my customers --- Im out to get people down the road in the most efficient manner with a high emphasis on dependability.

What i see in the trade is generally massive overkill, and it's not just that - some of it's counterproductive overkill to the point of creating more problems while adding expense, I don't work that way,
It's only one of the options if someone want's to spare no expense -- but it too comes with a clause, I caution people who think just because they replace a factory water pump @ their first timing belt change interval that it does not mean their not going to have water pump problems right around the corner - Incompetence is running rampant esp. in the parts department - many times if you have a good pump then stick with it (after a bearing and seal inspection) Ive seen mechanics replace a factory honda or toyota pump that most likely would have gone a total quarter million miles only to have the new one shell out in the next ten thou...

Experience is what I get paid for - and within this is the confidence that my customers have in me to make the right choice, Im also in tune with who they are and how deep or shallow their pockets are and what they use their vehicles for - Some are very anal and want everything replaced - others are just getting by - sometimes I go above and beyond "the book"
Or sometimes I have to tell them to junk the car...

Like Timeleech says - you have the discussion about options BEFORE you work on it -------- you can't guarantee an experiment and you make damn sure they understand that - but if the experiment is 1/8th the price of the other option and the other option is more than the vehicle or vessel is worth then you cover your butt by simple logic and they sign off on it beforehand -- there's no reason for anybody "getting pissed" - and there damn sure is no reason for a mechanic to get a bad rap, someone questions you about it you just tell them what, how and why.


Iv pulled off way to many minor little miracles to worry about what someone's going to think if something does go wrong - im tested and proven and there's no disputing it.
Example; A girl with a honda who went way to long on her timing belt - Its an interference fit engine and the belt breaks at Idle (which most do)
The engine almost makes it except one exhaust valve "kisses" the piston and bends, the girl has almost no money and all bets are off the table about the two of us hanging out together and having some fun due to her being a lesbian,,, ( like I say - I cover all options :p )
She can't afford a $450.00 cylinder head removal and the added sublet repairs and gaskets to boot, so I pull out one of my wild cards and throw a $160.00 option on the table - try as best as I can to explain it to her and she says "Go for it"



Two hours later Im flying down the highway in said car testing it out - the exhaust valve is sealed - the engine is purring like a kitten - the head was never removed and the car ran for 30,000 miles + till she sold it a few years later to buy a pickup, after that I lost track of it.

Everybody was happy including me as I got paid almost twice my normal shop rate for thinking outside the box and taking an educated guess, that's what good wrenching is my friend --- any monkey can read a book and follow directions,
but if that's the definition of being a mechanic then I would not be doing it...

Or maybe it is -- but it's sure not the definition of being a master mechanic.

All my decades of experimenting has for the most part taught me what I can get bye with and what I can't --- Its not only priceless - It makes you realize just how wrong the book is most of the time...

DICKEYBIRD
09-19-2010, 11:34 AM
Two hours later Im flying down the highway in said car testing it out - the exhaust valve is sealed. So, what'cha do? Stick something in the intake port, position it opposite the witness mark on the valve and gently bump the engine over by hand to bend it back? Just curious, sounds like a good plan to me.

A.K. Boomer
09-19-2010, 12:12 PM
Position said piston @ TDC - remove valve cover - remove exhaust manifold (no big whoop - engine was a 1.5 liter in-line 4)

remove exhaust rocker gear - mark the troubled exhaust valve position on top of stem - remove spark plug on said cylinder install comp. tester hose with internal valve removed (so it couples right up to air compressor hose with no restriction, or install leakdown tester if you own one) remove valve spring (special hand twist valve spring compressor designed for seal replacement without head removal)

Rotate valve 180 degree's and then connect air comp hose and note the amount of air coming out of exhaust port - disconnect

Allow valve to drop and rest on piston top - - with it 180 degree's from original position mildly hit valve stem directly with brass drift and a small hand sledge, (this is exactly the opposite of how the valve got bent in the first place - the piston angle against the canted valve is therefore Ideal)
repeat air test - start upping the ante and repeat till results are achieved to where one cannot hear or feel any air coming out of exhaust port - disconnect air --- let valve drop down - reach in exhaust port with finger and apply a small layer of valve grinding compound to part of the seat,

Hook up dewalt drill to top of valve stem and slowly rotate whilst pulling up - both reverse then forward,
- let valve drop again stick rag in and spin drill , do as best as you can to get grit out keeping in mind it is after all and exhaust and will be exiting soon enough anyways.

assemble and ship it....


Risks; valve head is weakened and it is also an exhaust which makes it more brittle and far more likely than an intake to break off destroying entire engine, also - initial bend was when valve was hot and more pliable - greater risk of failure while bending the valve cool --- Customer was aware of all risks as explained and still "went for it" as she really did not have any other options (did I mention she was a lesbian?)

Great attention to detail with bending process as it took many controlled small blows and about the same effort throughout range which I felt "good" about.

saltmine
09-19-2010, 12:46 PM
Kudos, AK. Good old fashioned "Mechanicing". Make do with what you have.

Unfortunately, in the automotive industry, that kind of repair is a thing of the past.
Today's current crop of "technicians" have enough trouble making a sandwich, let alone understanding the complexities of an engine and metallurgy. I know, I was an "old school" mechanic, before I retired.

Most shops and garages are more interested in their "bottom line" than they are in taking care of their customers. So, as a result, their customer is usually a one time affair.

To help with their "bottom line" most shops will hire haphazardly trained trade school graduates, and in a pinch, anybody right off the street. You never know who will be opening the hood on your $80,000 SUV these days.
It could be a trade school grad with a diploma in "Hot Rod Fabrication" or a drug seared high school drop-out, on amphetamines. One thing for sure, it won't be the guy who used to take pride in his work...he's gone, driven away by owner/managers cutting corners and wages, and owners/managers who place quantity over quality..

Don't believe me? Check it out at your favorite garage or dealer. What used to be a professional work place is now something between pre-school and "Teenage Musical". Older, trained mechanics spend much of their time fixing these kids' screwups and babysitting (another reason why the "old guys" are leaving the business)

It's good to know there are a few (very few) guys out there who are using years of experience and training to still solve problems for their customers.

If one of these kids got ahold of 'ol Kelvin, they would have recommended scrapping the boat or the engine...or replacing the engine with a cheap Chinese copy, at great expense.

The Fixer
09-19-2010, 04:36 PM
When (if) the Honda blows up and grenades the entire engine the cost of the repair goes up and way over the 'book' method, a risk that can be taken once assessed by the 'experienced' mechanic and may or may not work out for the best. I've worked many years in a automotive machine shop and have seen some pretty sketchy "repairs" by joe mechanic come thru for repair that ended up waaaaay more than the (failed) risk repair. I've also seen and heard of some pretty creative repairs go for a long time, the bent valve one of the most common actually and that still gives me the willies cuz the catastrophic damage when the valve fails makes for $ad faces.
In the case of the Honda a couple grand and a wrecker engine she's on her way, on the other hand I would hazard to guess that this boat engine could mount up to HUGE $ if the worst happens. And when these creative repairs do fail, in spite of all the earnest discussion and well intentioned repairs, people will look to blame someone else. They don't always tell their friends and relatives that they gave the go ahead on the risky repair cuz then they will look like the idiot when it goes awry.
I guess the bottom line for me is to understand that no matter how much you explained the options a associated risk a given percentage of clients will try to come back on you. I've learned my lessons the hard way, my house and families future is worth a way more to me than trying to save you $300.
It kinda falls in the same risk assessment some people do regarding insurance, some people drive their entire lives and never have an accident, most don't, when do you think you are going to have yours? When I have a new car it i fully insured when I'm driving the $1500 car, not so much...

Tim, there is a good chance that your repair will work for quite some time, everyone wins! You do (and have to) admit that there is a risk that it will not, in which case everyone loses! In spite of your giving the options and they picked one can quite certainly come back to haunt you in some way. You seem confident the risk you have taken will work out and I genuinely hope that it does. Let's face we all take some risks on a regular basis, you have demonstrated that you fully understand the technical aspects of the repair and have taken logical (though not ideal) steps to correct a problem under less than ideal circumstances.
It was not my intent to be negative, I was/am concerned that others without the benefit of your experience may feel that they can just disregard the 'book' when some repair is going to be cost prohibitive.

again just my .04
al

Peter.
09-19-2010, 05:04 PM
I was/am concerned that others without the benefit of your experience may feel that they can just disregard the 'book' when some repair is going to be cost prohibitive.



Would that not be THEIR failing for not realising the limits of their own abilities, rather than a concern for Tim for passing along his method of a remedy?

A.K. Boomer
09-19-2010, 05:48 PM
When I have a new car it i fully insured when I'm driving the $1500 car, not so much...



again just my .04
al



You said it not me, but let me reiterate --- I along with most owners (and it sounds like you also) will not do a $3,500 dollar repair/replace on a $1500 dollar car - Yet I will not send a $1500 dollar car off to the bone yard if there's a $300 dollar economical option that has a great chance of working out and the customer wants to "go for it"
Try to keep in mind where the car is heading if you don't do it;)

This was not some porsche with a hollow sodium filled exhaust valve that would most likely break - it was a honda, and while it's always been common practice for both air cooled porsche's and volkwagons to drop an exhaust valve on occasion and just for the hell of it (# 3 in particular on the early volks due to the oil cooler being in the way of the #3 cylinder head not to mention poor shroud design)
in all my years I have yet to see one drop in either a honda or toyota, and that's not just in regular running but in the event of a crash and bend, so in fact I know that they remain fairly pliable...

If "others" get in over their heads without using common sense and good judgment then its not a case for not trying to improvise - its a case for finding another "mechanic"...

saltmine
09-19-2010, 06:29 PM
I'm going to have to agree with you, A.K. I've performed some "questionable" repairs in the past, but they worked because I knew what I was doing, was careful, and usually, the customer was out of alternatives.

Once in a while, a "know-it-all" customer would demand a repair I wasn't comfortable with, and it usually ended with the same two outcomes; the engine blew up, and I got blamed.

When I was at the dealer, I had an old Chevy LUV come in with a blown headgasket. I removed the head, and, after cleaning, measured it for warpage. The Isuzu shop manual says anything over .007" of warp cannot be resurfaced. Mainly because the whole head is warped, which includes the camshaft journals. From experience I know attempting to true up camshaft journals cast into the head is quite expensive, and sometimes virtually impossible. The customer was informed and quoted the price on a new replacement cylinder head, and the labor to transfer parts and install it.
Needless to say, he had a hissy fit, and went stomping down to my work area, and demanded the damaged cylinder head, vowing to have it fixed, himself. About a week later, he stopped by, and delivered a freshly resurfaced head, all media blasted and clean. I saw the tag on the head and called the machine shop. Talking to the machinist, who happened to be a friend, I asked him how much they had to cut the head to get it flat.
He said the head was perfectly flat after the finish cut was taken...at .035"
Did he do anything with the cam journals? No, the customer wanted it resurfaced and nothing else. Oh boy....
As per the customer's instructions, I installed the head, and had a wonderful time trying to get the slack out of the timing chain (not only was the chain worn, but the cam sprocket was .035" closer to the crankshaft.)

Once assembled, the truck was road tested (it ran quite well with the extra compression) and returned to the customer.....no gurantee.

About a month later, my customer was sailing down the San Diego Freeway at 75mph when the stressed camshaft broke in the middle, promptly destroying the whole engine.
Of course, he came back. Mad as hell, demanding the dealership give him a new engine....We ended up going to small claims court....he lost.

A.K. Boomer
09-19-2010, 07:09 PM
Yes indeed that's a tough one Saltmine - Misaligned cam bores are labor extensive to repair and require some aftermarket to get into making the bearings due to the cam bores riding right in the aluminum head in the first place, or else you make your own bearing/sleeves.

Generally its the middle bore being higher than the ends, I have had them borderline and saved the entire mess by emery clothing in the center bore to a lower position so the cam rotates freely enough to run without seizing, since it was a rocker arm engine it means the valve spring pressure was exerted in this direction so the cam wasn't hanging out in "limbo" with no support on the center journal,
Never lost one but a practice I try to avoid...

I can tell your a good improviser --- Iv done some major hack work on most all my personal vehicles just to see what I can get away with --- in this arena even a total failure is a mini-success.

Whats the saying ? Good judgment comes from experience - and much experience comes from bad judgment...;)

Arcane
09-19-2010, 08:45 PM
Anyway, after allowing to cool and releasing the cap from the former, it was still about 6 or 7 thou undersize at the opening, so I repeated the process with a strip of 4 thou shim under the former. Result, the cap is now within a thou of an undamaged cap so should be OK.



Wear to the inside of the cap appears to be no more than a slight polishing. As said, I'll be checking clearances with Plastigage strips before final assembly.


I am convinced that no significant material has been lost from the cap, it's simply a distortion issue. The new top shell slid into place with exactly the same level of ease/difficulty as all the others. I've measured the crank journal as best I can, good old fashioned firm joint calipers were the only option given the limited access and it's within a thou or so of original (and it is 42 years old). The maker's s pecs allow for a bearing clearance of up to 14 thou before work is needed, from a new clearance of 4.5 to 7 thou. I've discussed this with my local friendly engine reconditioner, in case he had tried anything similar or had any better ideas. He hadn't, but has seen the cap and has approved of my methods.


I nipped the cap up yesterday, with new shells and a strip of Plastigauge at about 4 o'clock. It came out showing 7 thou clearance.

Thanks for posting your creative repair, Tim. It seems there are several people who blew by the numbers you posted and don't realize you are well within spec for bearing clearance and have in fact done everything necessary to make this a lasting field repair. I'm sure there were more things you checked that you didn't post simply because they would have been such basic checks to do and you didn't feel the need to tell us about them.

I'm also sure the owners will be very happy with the repair and are very impressed with your ability to think outside the box.

saltmine
09-19-2010, 08:51 PM
I try not to improvise. Usually go with the "book correct" fix, but there are times when the book goes right out the window.

After nearly 50 years in the automotive business, I can't count all of the mistakes I've made, but I don't make them twice.

Having a good background in machining and welding I sometimes get "carried away" with a "cost effective" repair instead of breaking the bank and doing it "by the book".

I started early. As a young guy, on my own, I bought a motorcycle(my first) of questionable origin (German/Czech). I paid for it out of my own money (Not much fortunately), and rode it proudly. Unfortunately, the piston ring broke and hung in the exhaust port, fifty miles from home, locking the engine up. I opened the meager toolkit that came with the bike, and removed the cylinder head, on the side of the road. Once I saw the broken ring, I fished it out, pulled the barrel and removed the rest of the broken pieces. In the dark, I reassembled the engine without the ring, and managed to actually get it running. Yes, I made it home. The last mile I had to resort to shifting the bike into fourth gear, and used the kick-starter to power it home. The bike never ran again, but it got me home. MAcGyver would have been proud of me.

clutch
09-19-2010, 09:08 PM
No gap, I'm confident there's no damage to the crankcase bore. There's none to the cap apart from the distortion, and the cap is what takes the load.

I started this thread just because I thought others might be interested in my method for reshaping the distorted cap, not interested in all the argument and negativity, the 'it'll never work!' stuff. I'm happy with what I've done and that the owners will soon be able to get their barge earning money.

Tim

Tim,

I was not slaging you. I just asked a question that if was there, I'd have answered myself.

I fix things for a living, sometimes in compressed time frames. Good enough is. Quite often.


Clutch

Carld
09-19-2010, 09:23 PM
Since I am not a Master Mechanic or Master Machinist I too have done what I call shade tree work. Sometimes it works, sometimes it fails. When I do something that I know is not the right way I always tell the customer there is a strong possibility it will fail and there is no warranty and if there is an invoice it's on the invoice as well.

If in my mind it will never work I refuse to do it and let some other sucker do it.

Since I wasn't there I don't know if I would have done what he did or not but it is a gamble at best and it may work. On the other hand there is a reason the bearing failed and the possibility it will fail again is very likely. Since the owners know there is no come back and Timleech is happy there is nothing more to say about the job.

There is the possibility I would have done the same given the circumstances.

A.K. Boomer
09-20-2010, 04:00 AM
Since I am not a Master Mechanic or Master Machinist I too have done what I call shade tree work. Sometimes it works, sometimes it fails. When I do something that I know is not the right way I always tell the customer there is a strong possibility it will fail and there is no warranty and if there is an invoice it's on the invoice as well.

If in my mind it will never work I refuse to do it and let some other sucker do it.

Since I wasn't there I don't know if I would have done what he did or not but it is a gamble at best and it may work. On the other hand there is a reason the bearing failed and the possibility it will fail again is very likely. Since the owners know there is no come back and Timleech is happy there is nothing more to say about the job.

There is the possibility I would have done the same given the circumstances.


So your one of us after all! Sorry for labeling you "by the book"

You bring up a point that's very important and that's that the bearing failed once so whats to stop it from failing again --- but Timeleech stated in his OP
that the engine ran without a filter;


"and there had been an issue with the oil filtration (ie there hadn't been any for some time!) in the past."


And im glad you made me go back to dig this up because then I found;



"Anyway, nearly had them all done yesterday apart from final tightening when I found that the centre main had spun in its housing, and then discovered that the bearing cap was distorted, the sides had come in by about 15 thou. This was the one I least expected to be trouble, as it's the first in line for the oil feed."

So my question to Timeleech is why would you expect the first feed to be trouble free if there's potential debris in the oil???
Your thinking conventional - first feed lives due to getting the most oil and pressure - but debris changes the entire ballgame.

Its the first feed that's at the most risk as not only does it get the most volume (and therefore debris) but also is the first to experience the centrifuge effect of the spinning crankshaft which virtually pins the debris to the bearing surface from the journal port...


Anyways --- I think we may have found the initial failure point... and that's always reassuring when attempting something of this nature, at the very least its nice to have a working theory in place...

Saltmine thanks for sharing --- its great to here other "tales from the crypt" ;>}
And in the dark to boot!

Timleech
09-20-2010, 05:20 AM
So my question to Timeleech is why would you expect the first feed to be trouble free if there's potential debris in the oil???
Your thinking conventional - first feed lives due to getting the most oil and pressure - but debris changes the entire ballgame.

Its the first feed that's at the most risk as not only does it get the most volume (and therefore debris) but also is the first to experience the centrifuge effect of the spinning crankshaft which virtually pins the debris to the bearing surface from the journal port...



Just based on experience really, generally it's the bearings furthest from the supply which get the most wear. I own a later 8-cyl turbocharged version of the same engine which had a seized front main (furthest from the supply) when I bought it, the next main was bad, the rest were near perfect.
Based on my experience we looked at Nos 1 & 7 mains first, working in to 3 & 5, and they did more or less follow that pattern. The rest had to stay in place until the others were replaced, and it takes getting on for an hour to undo one main cap and spin out the top shell so we didn't rush to put them back with old shells to look at the others. With hindsight perhaps we should have done, but I doubt that it would have changed any decisions. Lack of filtration isn't always a killer, there are thousands of small diesels from the same period which have never had any filtration, from new, beyond a crude sump strainer and still running fine today. I'm sure it's been an issue here, though.

Tim

Circlip
09-20-2010, 06:51 AM
FFS, good fix Tim, the customer was informed of a temporary fix to get the show on the road until a more convenient time when a more permanent repair can be undertaken. His decision.

Don't wonder his knibs got p****d off and dissapeared. Wonder how the "Gallery" would feel about the practice of the narrow boat makers in the past fitting an ex-scrapyard Lister single from a cement mixer straight into a new build boat after washing the exterior of the engine down and changing the oil?

Regards Ian.

aboard_epsilon
09-20-2010, 02:10 PM
Not main bearings but improvisation all the same

Today
Stupid little plastic clip snapped off my door pull on the car ..
the clip was tiny and probably cost all of 0.00000001 in plastic

anyway phoned the parts place up ..

5.95 plus the vat ..plus delivery

so ...it got this instead


http://img.photobucket.com/albums/v190/aboard_epsilon/P1010158.jpg

from this

http://img.photobucket.com/albums/v190/aboard_epsilon/P1010161.jpg

those electrical blocks have pulled me out of a mess lots of times ..they are also good for lawn mower throttle cables etc .

all the best.markj

Timleech
09-20-2010, 04:14 PM
FFS, good fix Tim, the customer was informed of a temporary fix to get the show on the road until a more convenient time when a more permanent repair can be undertaken. His decision.


Regards Ian.

Ian

Customer informed and involved, but I don't see it as necessarily temporary ;)

If it runs freely after final assembly, and I'll check bearing temps as best I can, I don't see why it shouldn't last until the crank needs a regrind - and that might be a long way down the line.

Cheers
Tim

The Fixer
09-20-2010, 05:07 PM
I'm pretty sure it will last until the crank needs a regrind too. Of course it could be the cause of the crank needing a regrind if it doesn't work out... but now I'm just being negative! Lol
You could be right Tim, it could go for a long time, mains are much more forgiving than rods... yep by golly it does feel much better when you are more positive!
These kind of repairs (and I've done them too) can keep me awake at night for a few nights until I get past that "if it was gonna go, it would've gone by now" period.
I'm really not trying to give you the gears about what you chose to do.

al

Circlip
09-21-2010, 05:06 AM
I don't see why it shouldn't last until the crank needs a regrind - and that might be a long way down the line.


That's what I meant Tim, not a detraction from your skill.

Regards Ian.

TGTool
09-21-2010, 12:36 PM
Lack of filtration isn't always a killer, there are thousands of small diesels from the same period which have never had any filtration, from new, beyond a crude sump strainer and still running fine today. I'm sure it's been an issue here, though.

Tim

That reminds me. At a previous job I received an inquiry for spare parts for a product made by a company with a similar name, not ours at all. When I looked into it, the product was for marine engines and was composed of a pump and metering to withdraw a small portion of the engine oil from the sump and add it to the fuel stream as it was being replaced by new oil to maintain level. In other words, instead of filtering, the lubricating oil was just gradually replaced over time. It may have been an aftermarket product and may have found a market for those engines without filtration.

DICKEYBIRD
09-21-2010, 02:21 PM
In other words, instead of filtering, the lubricating oil was just gradually replaced over time.I think Cummins has a system like that for big truck engines.

RPM
09-21-2010, 03:04 PM
Hi Tim,
Thanks for all the pictures and explanation of what you have been doing. I have found it astonishing that you've had such criticisms from guys who know little or nothing of your situation.

As in AKB's Honda case, I'm guessing that the boat owners can't afford any better at this time, and if you didn't make the engine workable, then it would be the end of the road for boat, engine and owners. How often have we seen a rusty boat laid up in the weeds, and seen what a sorry sight it is, and yet you stuck your neck out and changed that picture.

I had to chuckle after some of the critics sounded off, when you quietly pointed out that you owned a similar turbocharged version of the same engine, without making a big deal of it that you obviously had a great deal of hands-on experience with this engine design. You have obviously figured out the problems with the oil flow and flitering on your own engine, so using this hard-won knowledge on a similar engine is a very safe move.

Your point about the low RPM and that other similar engines went on for years with little lubrication seems to gone over the heads of our 'Monday morning quarterbacks' for whom hindsight is always 20/20.

Keep up the good work, we need engineers/mechanics like you to show the 'book-reading' theory guys what work in the field, dirty, exhausting and not well-paid, is still all about. And besides, you have an active independant brain, similar to Sir John, showing us all (without really wanting or needing to) how we all could be if we had less fear and more imagination .

Richard in Los Angeles

The Artful Bodger
09-21-2010, 04:08 PM
In other words, instead of filtering, the lubricating oil was just gradually replaced over time..

All British motorcycles use that same system.

Circlip
09-22-2010, 05:47 AM
All British motorcycles use that same system.

Yep, but the addition was a manual proccess.:D

Regards Ian.