Piston rings leaking on air compressor

[A.K. Boomer]

And you're still worried about a mild abrasive that degrades in minutes?

Not good practice, again - getting one side of a bore blasted by it whilst the other side skates free is hardly any way of controlling anything - even hackery... it's junk practice...

[Black Forest]

One of the first things I checked was the crankcase breather. One of the things that makes me think it is the rings is when I did check the crankcase by taking out the filler plug on top when the compressor was running a lot of air was coming out the hole. Much more than I remember on previous checks. Too bad I couldn't just slap some O-rings in the three ring groves.

[tlfamm]

Isn't it Bon Ami that used to have a picture of a new hatched chick on the can, with the words "Hasn't scratched yet"?

That was their deal, not really abrasive enough to hurt anything.

Indeed. We used Bon Ami to clean the parabolic mirrors in the carbon-arc light sources of our motion-picture projectors.

[Dave C]

Back in the late fifties and sixties the Bon Ami treatment was quite popular when chrome rings refused to seat. Those were different times, when oil was changed every thousand miles, and metallurgy was primitive by today's standards. It's not something I would recommend doing today.

[Willy]

Indeed. We used Bon Ami to clean the parabolic mirrors in the carbon-arc light sources of our motion-picture projectors.

Indeed Bon Ami is a very mild abrasive cleaner that can usually be used on most surfaces without harm. Hey I've use it myself in the past for it's intended purpose and have always been pleased with the results.

But most folks don't scrub with as much vigor or intensity as that which is present in an engine's cylinder/piston ring interface. At an average engine speed of 2,500 RPM the piston makes one complete up and down cycle in the cylinder 2,500 times in one minute.
This works out to 150,000 cycles in only 1 hour, or 15,000,000 times in a 100 hour period! It's not even due for an oil change yet.
The sheer numbers alone are staggering, now combine this fact with the pressure and heat experienced between the ring and the cylinder and tell me you want this to last.

Even the directions warn of possible visual damage to sensitive surfaces.

http://www.wegmans.com/webapp/wcs/stores/servlet/ProductDisplay?productId=785060&storeId=10052&langId=-1

Directions Wet surface. Sprinkle on Bon Ami. Rub with wet sponge or cloth. Rinse. Note: On delicate surfaces like fiberglass, imitation marble & plastic, sprinkle Bon Ami onto a wet sponge, use plenty of water, rub gently and rinse. Always test first in an inconspicuous area on delicate, polished or glossy surfaces. Do not use on windows or mirrors. Bon Ami is a mild abrasive cleaner. Do not use on surfaces that a manufacturer states should not be cleaned with abrasive cleaners. If the manufacturer of brushed metal surfaces approves use of an abrasive cleaner, you must always rub in the direction of the brush lines. Store in a cool, dry place.

[ahidley]

I didn't read all the replies. But here is an easy way to make rings the right way. Go to jerry Howell website and he had a n article on how to make a fixture to make the rings for his V2 engine with one inch dia pistons. Now out you do need centrifically cast cast iron. Thus it's spun while being cast. This makes the grain around in a circle, just like rings on a tree. Thus it's stronger for round things like rings. Cool project.

[A.K. Boomer]

"If the manufacturer of brushed metal surfaces approves use of an abrasive cleaner, you must always rub in the direction of the brush lines."

Well there you go --- even if a hillbilly engine manufacturer recommends dumping copious amounts of limestone into your engine you better have one of those "corkscrew" crank and rod designs that make the piston rotate as it's going up,
says right there in print always rub with the brushed lines (crosshatch) --- geeze wonder why? could the stuff actually be abrasive? (duh)

hey I got an idea, why don't I just leave my valve cover off and drive down a dirt road for a bit... or heck just sweep the shop floor with it off every valve adjustment to "extend" the life of my engine...

look - this is kinda getting silly now ain't it?

[oldtiffie]

I have a three cylinder single stage cast iron air compressor pump. It is leaking air past the piston seals so it won't build full pressure. Is there anything I can do to fix this problem? I have no idea what make the pump is or from where. Getting spare parts is out. It is blowing some oil from the crankcase into the airstream. I find oil in the air filter on two cylinders.

If that compressor were mine at this state of the thread etc. I'd probably remove at least the head of the worst leaking cylinder and see what the condition of the reed/"flap" valve and its seat were in. I'd then see if it was worth-while removing the other (2) heads for the same reason.

If spares were available (which the OP (BF) advises they are not) I'd decide the cost, scope of works and probable project time and make a "costs-versus-time" evaluation and see it if was worth-while and proceed on from there.

If having the compressor ready as soon as possible was urgent or critical I'd be very seriously "binning" the compressor for a new/replacement one.

At this stage, and if it were me, I'd be binning the compressor and getting a new one.

But as always, it is entirely up the owner of the compressor (BF).

Oops - my apologies.

I missed this post from BF who it seems got (very?) "lucky".

You guys are going to love this one. I told the wife that the compressor was toast but I think I can fix it. I will order some cast iron and turn three new pistons and make some rings. Hopefully that will solve the problem. She asked if I knew how to make pistons and rings. I told her no but I am sure the guys on the forum will help me get through the project. She looks at her watch and says if you hurry you can get to the tool store and buy a new compressor before they close. And on my way out the door she tells me to buy a good one so I can get some work done and not spend my time fixing my tools. I grab my hat while ringing my hands with a devils smile. I bought a two stage 800 liter per minute constant flow with a 200 liter tank. Compressor head is from a good firm in Italy. The pressure switch is from Condor here in Germany. 3 phase motor 5.5KW. And it is quiet. Not a gloat as I paid full retail.

Maybe I will try to fix the old one just to try my hand at making pistons and rings.

[Dave C]

"If the manufacturer of brushed metal surfaces approves use of an abrasive cleaner, you must always rub in the direction of the brush lines."

Well there you go --- even if a hillbilly engine manufacturer recommends dumping copious amounts of limestone into your engine you better have one of those "corkscrew" crank and rod designs that make the piston rotate as it's going up,
says right there in print always rub with the brushed lines (crosshatch) --- geeze wonder why? could the stuff actually be abrasive? (duh)
hey I got an idea, why don't I just leave my valve cover off and drive down a dirt road for a bit... or heck just sweep the shop floor with it off every valve adjustment to "extend" the life of my engine...

look - this is kinda getting silly now ain't it?

I had my introduction to the BonAmi trick in the early sixties, while working in an automotive machine shop. We built a new Chevy engine for the owner's modified dirt car, and after the routine break in run up was completed, it was still smoking pretty good. We were contemplating tearing it down to replace the chrome rings, but were pressed for time since the car was supposed to race that night. The boss shut it down, went into the janitor's closet and came out with some white powder in the palm of his hand. He cranked the engine up and blew the powder over the injector stacks, and in less than a minute the engine stopped smoking. We pulled the injectors off, washed them out, changed the oil and spark plugs, and the car won the feature race that night. You can call it Hillbilly mechanics, but it worked. That said, it was not done to an engine that was expected to go 100,000 miles.

[A.K. Boomer]

That said, it was not done to an engine that was expected to go 100,000 miles.

All I can say is if it made that much of a difference then imagine the incredible amounts of wear it threw on all the parts in the process,,, that's crazy and like I say totally uncontrolled...

Geeze think about things like the oil gummy intake valve stems in the open position catching and retaining a full blast of powdered abrasive mineral dust then getting stuffed back into their guide 25 times a second...

change the oil all you want - that stuff is there to stay and incidentally is on the side of the valve stem and guide that is bearing most all the side load from the rocker arm just by nature of design... Nice,,, see how an experienced mechanic thinks?

again - not worth trashing an entire engine over, pull an all nighter and fix it right or kick everyones butt whilst throwing out a smoke screen but for gods sake don't throw abrasive powders down the intake track of your engine...

it's not just hillbilly tech - it's plain stupid...

[Black_Moons]

What do you mean, the abrasive is left in them? When I worked at one of the big three, cleaning out any residual was a requirement. They used special brushes, and a process I don't know the details of. I was always told that proper cleaning of honed cylinders was a critical step when I was assembling racing engines.

When was the last time the oil was changed?

For honing cleanup, Proper method is to clean with solvent till rag is clean, then clean with soap/water till rag is clean, then oil.. and wipe some more till that rag comes out clean!

A far cry from 'Lets throw it in there and leave it' the other people are suggesting.

[Glug]

Another thought on the bon-ami trick is that oil control was much worse in older engines. They splashed and pumped much more oil around, everywhere. Obviously no one is suggesting using that trick in a modern engine, but I can see where it was more appropriate back in the day. Especially by someone who would get paid to do the job over.

A while back someone here mentioned using JB weld to repair scoring on 2 cycle cylinder walls. That sounded like a neat trick, and I imagine it might work even better in a compressor. A friend is stuck half way into a compressor re-build (Quincy 106-15), and I suggested that as an option, if necessary. Though his problem is a worn crankshaft, not cylinder scoring. He'll either need a replacement crank, or it will need to be welded and re-ground (which is prohibitively expensive unless he can find someone to do it cheap). It looks like it might have lost oil over time and run dry.

[Glug]

For honing cleanup, Proper method is to clean with solvent till rag is clean, then clean with soap/water till rag is clean, then oil.. and wipe some more till that rag comes out clean!

Yes. And I have always understood that the detergent step was crucial - solvent alone is not sufficient. The process at the big three involved some extremely stiff brushes to mechanically clean the bores. I always wanted to get one of those, but it didn't work out

I always cleaned blocks with solvent, then with powdered laundry detergent and hot water. And then, with lots and lots of WD40. I think that is one of those extremely rare cases where WD40 is actually an appropriate product to use. It does a good job of displacing the water.

[Dave C]

All I can say is if it made that much of a difference then imagine the incredible amounts of wear it threw on all the parts in the process,,, that's crazy and like I say totally uncontrolled...

Geeze think about things like the oil gummy intake valve stems in the open position catching and retaining a full blast of powdered abrasive mineral dust then getting stuffed back into their guide 25 times a second...

change the oil all you want - that stuff is there to stay and incidentally is on the side of the valve stem and guide that is bearing most all the side load from the rocker arm just by nature of design... Nice,,, see how an experienced mechanic thinks?

again - not worth trashing an entire engine over, pull an all nighter and fix it right or kick everyones butt whilst throwing out a smoke screen but for gods sake don't throw abrasive powders down the intake track of your engine...

it's not just hillbilly tech - it's plain stupid...

Call it what you like. You must not have any dirt racing experience. Missing out on a chance at the feature win money with a highly competitive car, WOULD have been stupid. Incidentally, the back up engine popped a valve head off during it's break in run, and put us in a bind to get going again. Those engines were completely torn down after each weekend of racing. The dirt in them from one heat race is a lot worse than a gram or so of BonAmi. This was not some shade tree, hillbilly program.

[A.K. Boomer]

Built many a race engine here, if your batting two for two on both the main engine and the back-up engine shooting craps and then counting on a pot and pan cleaner to save your hide you just might want to analyze your build technique's and parts choice a little more carefully --- but just a suggestion...