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CaptMike
01-23-2013, 09:01 PM
We are on our fifth engine (2 different brands) and have a recurring problem. I'd post this on another site but its a dead horse if its posted to anything titled outboards, and there is no definitive answer from either manufacturer. That being said,

After a year we routinely change water pumps on our outboards which involves pulling the drive shaft from the crank, or its supposed to work that way. And I've put the question out to our other franchise owners and same problem. Only several fixes which all involve wedges, heat, cold, soaks and heat, if nothing works, cut the shaft, machine out the remaining shaft, put in a new shaft. We have lubricated the splines and so has every other person who's had this problem, and it seems everyone has a problem separating the two.

So, I have honed gears, bearings and spline in the Navy for sound/vibration abatement and it occurred to me that we did the same fitting with Dykem, hone the high spots with just about everything.

Any machinist or engineering advice on why this would not improve a fit that is a "production" machined fit and obviously does not work? For some reason no one can explain or has not bothered to find out (its much easy to keep replacing parts mentality)

All I plan to do is ensure both male and female splines are clean, paint with Dykem or Prussian blue, dry fit and see whats what. I would imagine I'll find a typical production machined spline fit.

Any thoughts

darryl
01-23-2013, 09:24 PM
I wonder whether it's the OD/ID fit that's getting tight, or the splines themselves- If the former, it would seem that the simple act of polishing the OD might do the trick. Maybe something a little more aggressive, like sanding would be needed. You would use the existing machining marks as a guide by keeping the pattern you produce looking fairly even. If you took off all machining marks, you'd have gone too far as then you have nothing to relate your progress to. I'm assuming that any machining marks left would not be deeper than a half thou or so, and that you'd be removing only a fraction of that.

If the splines themselves are tight, that could be for several reasons. One would be that they are manufactured to that degree of tightness, another would be that they don't get enough deburring after machining, and another would be that they burr up to some degree during use. I would be inclined to try polishing off any sharp edges on the splines before assembling the parts.

Just some ideas.

CaptMike
01-23-2013, 10:10 PM
My thoughts also. I'm planning now on taking a bore scope and looking at ID. I'm pretty sure I'll find machine marks and I think that's the whole problem so we'll see. At the least, all I'll do is take off some high marks and polish the rest. I'll post some pics.

thanks for the input. its worth saying that I did get a reply from one of "their" engineers saying there was no need to custom fit anything. I asked if he was aware of the problem, he was, but had no answer. He also said it was impossible for lubrication to hydraulic lock the two. Not quite sure he was an ME.

oldtiffie
01-24-2013, 03:01 AM
Perhaps the mating parts are "bruising" each othet and raising a "mound" at the end (sides too?) of the mating parts.

If that's so its a manufacturing/design problem.

Perhaps remove the pump more frequently before the mound becomes an obstruction and remove any "raising" if necessary.

vpt
01-24-2013, 08:39 AM
I have never ran into the problem of not being able to get the lower unit off because of a stuck shaft. Some do get a bit tight but still they always come apart with a little prying. Do you ever see rust on the shaft when you pull it out? Sometimes the female side can get some rust in it and cause a tight fit. Is the shaft tight the whole way or does it get tighter the deeper in it goes? Should be no problem at all honing the splines a bit, I just wouldn't make it too loose as to where the splines can chatter while running causing wear.

We run sandy, rocky, stump filled rivers. I as well go threw out motors at the end of the season for maintenance and whatnot. Sometimes they even get emergency mid season tear downs. Those aren't fun.

Pulled apart for a bent prop shaft, shaft started at .700 out and ended up .006" out. Back in service runnin nice and smooth again.

http://img831.imageshack.us/img831/8277/propshaft003.jpg

http://img412.imageshack.us/img412/4619/propshaft011.jpg



I agree those boat forums are slow as molasses.

big job
01-24-2013, 09:50 AM
Air powered flap disk is your freind.

CaptMike
01-24-2013, 10:38 AM
These engines are Yamaha and Suzuki Four strokes. We have learned that this occurs with engines model years from 2002 up. Granted we put about 800 hours on a engine a year, but we've found that the problem exists with recreational engines as well as those used in the military and of course, with the commercial towing industry.

And there has been every conceivable method to coax these shafts out of their respective housing with varied results. I've taken the "old" shafts and measured them for warp, torsion slipping ( I took a cross section of shaft and looked at under a microscope) and nada. No rust, metal shavings, no filings. I've checked for mushrooming at the ends and yes for mounding and bruising. There is no indicator why this is constantly failing.

The lube that we use on the ends is milspec Mobilegrease 28, and I even took a sample of "old" grease and had it analyzed for contaminants, (I was look for salt) nothing.

The only thing no one has ever done is polish the shaft end and receiver (crank) and check for hydraulic lock between the shaft end and the crank.

lbhsbz
01-24-2013, 12:32 PM
These engines are Yamaha and Suzuki Four strokes. We have learned that this occurs with engines model years from 2002 up. Granted we put about 800 hours on a engine a year, but we've found that the problem exists with recreational engines as well as those used in the military and of course, with the commercial towing industry.

And there has been every conceivable method to coax these shafts out of their respective housing with varied results. I've taken the "old" shafts and measured them for warp, torsion slipping ( I took a cross section of shaft and looked at under a microscope) and nada. No rust, metal shavings, no filings. I've checked for mushrooming at the ends and yes for mounding and bruising. There is no indicator why this is constantly failing.

The lube that we use on the ends is milspec Mobilegrease 28, and I even took a sample of "old" grease and had it analyzed for contaminants, (I was look for salt) nothing.

The only thing no one has ever done is polish the shaft end and receiver (crank) and check for hydraulic lock between the shaft end and the crank.

If you eventually do get it apart and clean all the lube/crap off of the driveshaft and the inside of the crankshaft, do the pieces fit back together nicely? Can you then immediately slide them back apart? If so, I would lean towards the shaft hydraulically locking together. I run an old 2.4L merc, and have the lower unit off quite often. I use a very small amount of grease, generally the red sta-lube extreme pressure stuff. I like it because it's not very sticky and is a fairly low viscosity. I never have a problem getting it apart.

HWooldridge
01-24-2013, 01:44 PM
These engines are Yamaha and Suzuki Four strokes. We have learned that this occurs with engines model years from 2002 up. Granted we put about 800 hours on a engine a year, but we've found that the problem exists with recreational engines as well as those used in the military and of course, with the commercial towing industry.

And there has been every conceivable method to coax these shafts out of their respective housing with varied results. I've taken the "old" shafts and measured them for warp, torsion slipping ( I took a cross section of shaft and looked at under a microscope) and nada. No rust, metal shavings, no filings. I've checked for mushrooming at the ends and yes for mounding and bruising. There is no indicator why this is constantly failing.

The lube that we use on the ends is milspec Mobilegrease 28, and I even took a sample of "old" grease and had it analyzed for contaminants, (I was look for salt) nothing.

The only thing no one has ever done is polish the shaft end and receiver (crank) and check for hydraulic lock between the shaft end and the crank.

Just a random thought but how about applying anti-sieze instead of grease. Grease has a tendency to get sticky with heat and pressure so you may be inadvertently creating an adhesive seal.

If hydraulic lock is occurring, you might be able to machine a small relief groove at the bottom of one or two of the splines to allow a "breather" between the parts.

vpt
01-24-2013, 06:29 PM
Or just light oil, these splines really don't need lubrication because they don't slip. They more or less just need a coating of something to keep rust at bay.

michigan doug
01-24-2013, 10:28 PM
I immediately thought to use anti-seize as well.

How many do you have to fix/service in a year?

Do an experiment with different techniques.

Sandblast one, lightly of course

Polish another

Lap a third one

Pressure relief/vacuum breaker channel in another.

Talk to a better engineer--very unsatisfying that they won't make useful recommendations.

finest regards,

doug

vpt
01-25-2013, 08:31 AM
Like mentioned some steps need to be taken here. First the joint needs to be tried dry to see if like mentioned it is not hydro locking. Then if still tight the splines need to be blued and checked where they are rubbing, on the tops of the splines, bottoms, sides, what have you. Then after the problem is found light corrections need to be made to the high spots and slipped together over and over again till it fits right. Then lightly oil and assemble and wait for next tear down.

outlawspeeder
01-25-2013, 12:12 PM
What type of out drive?

CaptMike
01-30-2013, 11:35 AM
No outdrive, outboard longshaft.

Well we did all we could and finally cut the shaft. Now its off to the machine shop for a bore out. I even put a slide hammer on the remaining shaft and no joy. Looking at the schematic, there is a bushing that is pressed into the end of the crankshaft and the driveshaft fits into the bushing. So now its a bushing deal. I have found several forums on outboards in which more than several "others" have had the same problem. Replacing the bushing is a major tear down and I can't see where putting in a new bushing would correct the problem, long term. several have stated they have left the bushing out with no problems on a recommendation from their mechanics.

That being said, I'm looking for engineering/machinist fixes, no disrespect to our mechanics.

SVS
01-30-2013, 06:41 PM
I have no idea what your assembly looks like, so this may not be possible...But, can you drill and tap for a grease zerk on the side of the female coupling? Jack it apart with a grease gun.

CaptMike
01-30-2013, 07:25 PM
Yes! I can drill thru an exhaust port and get to the bushing, drill and tap for a low profile zerk. However I'll have to deal with exhaust heat.

I have the new shaft in hand and the spline end in question and the tops of the splines are keyed or lightly stepped and the valleys are smooth (well they will be because they are nothing but tool chatter marks now)

http://www.danssouthsidemarine.com/assets/layouts/main_layout/parts/DT150_200(86).pdf

Figure 29 Part49

Bill736
01-30-2013, 07:40 PM
For some reason, using old fashioned " white lead" sounds like an appropriate substance . Years ago, we used to put white lead onto the splines that held wire wheels onto some sports car axle hubs ( Jag or big Austin Healy ?) and at the time it was considered the best. You probably can't buy it retail anymore, but someone somewhere has a big can of it just sitting around.

CaptMike
01-30-2013, 08:17 PM
I remember using it extensively in the Navy but only on lathe centers. Planning on using Never Seez pure nickel .

Dr Stan
01-30-2013, 09:05 PM
Just a random thought but how about applying anti-sieze instead of grease. Grease has a tendency to get sticky with heat and pressure so you may be inadvertently creating an adhesive seal.

You beat me to it. My first job after the Navy was in a small boat yard in Bradenton, FL. We used anti-seize on essentially everything so we could disassemble it later after it had been used in salt water. Sure made life easier. That's also when I learned about putting anti-seize on automobile battery posts/terminals to virtually eliminate corrosion.

1-800miner
01-30-2013, 10:05 PM
I was thinking of the grease zerk idea as well. If heat is a problem,maybe you could pipe plug the hole until tear down time then install the grease fitting.
Is the exhaust heat doing something to the splines?could that be the problem?

MrSleepy
01-31-2013, 04:45 AM
It may be a cold welding / galling problem ...which may not be obvious with a naked eye.

Make sure the anti seize you purchase mentions cold welding / galling as not all do..

I was also wondering if low volt galvanic corrosion due to potential differences between the motor and pump are occuring, probably BS but you never know.

Rob

vpt
01-31-2013, 08:14 AM
Can you see the bushing? Is it brass? This sucks! Have you ran OMC outboards before? Like them, don't like them? If not you should try one out next time. We have had nothing but good luck with all of ours and they seem service friendly.

MrSpleepy there shouldn't be any static build up or the like because the water pump is rubber. That and the metal shaft makes metal contact with bearings/gears in the lower unit and the crank in the motor.

krutch
02-02-2013, 06:56 PM
Don't know if it was suggested 'cause I didn't read all these posts. If you melt some lead around a rod inserted into the spline bore and let it harden. Then push the rod & lead partway out of the bore and coat the lead with lapping compound. Work it back and forth in the spline bore to polish the ID. Works for gun bores.

Peter S
02-02-2013, 07:52 PM
I am no expert on grease, but couplings require special grease to prevent fretting corrosion. It used to be moly grease (grease without moly will not stop fretting corrosion), but now there are other special greases, the grease we get with motor-gearboxes is a white paste. Sorry no brand name.