Broken piston ring

engines

#1

I tried to repair an engine with a broken piston ring by simply replacing the ring with a stock ring but it broke again. What would be the cause of this - a worn and tapered bore?


#2

Rings will put up with SOME taper as they go up and down. I think something else is at work here. What sort of engine was this? What condition were the piston’s ring grooves in? Carboned up? Did you scrape the groove out? Was there sufficient end gap for the ring to expand? Did you do anything other than replace a ring while you were in there?


#3

To be honest, this happened to a freind a long time ago and I am just trying to educate myself. This hasn’t happen to me (yet)and I don’t know all the particulars of the piston. However my car, a 1998 Chevy Cavalier has a 2.2 L. engine with almost 200,000 miles on it. If this does happen to me when say it has 250,000 miles on it, I was wondering how little I could do to repair it such as dropping the piston out the bottom without pulling the engine. It sounds like I would have to really rebuild the engine then or at least take measurements of the cylinder?


#4

Cav: It really pays to be up front on boards such as this. You did not have the problem and cannot give specific info to questions such as Mg McAnick asked. you’re now asking about a hypethetical problem which you might encounter when your engine has 250K on it.


#5

On a 2.2, I would not drop the piston out the bottom, I would pull the head, ream the ridge at the top of the cylinder, and pull it out the top. In the case of the broken ring that your friend had, if it was the correct ring and it was installed properly (as MG McAnick said, scrape out the ring land, check end-gap) I would guess that there was damage to that piston’s ring land which caused the ring to seat improperly.

If you do get to 250k and find that you need a ring job, places like http://www.northernautoparts.com sell re-ring kits for a few hundred dollars, and on a 2.2, you could probably do it with the block in place.


#6

It sounds to me like someone inexperienced was doing this repair and forced a piston with new rings back into a ridged cylinder, thereby breaking the new ring instantly.

It’s also possible that the original ring was broken by whoever attempted to force the piston/rings out past a cylinder ridge and broken rings had nothing to do with the original problem, or perceived problem.

If someone does not know how to use a ridge reamer, inside micrometers, etc. then they have no business messing with it; and pistons will only come out the top - unless the engine is blowing up.