Thread: Broken Piston Rings

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Can I get some opinions of what would cause broken piston rings? When I tore my engine down, I found 3 broken piston rings. One of them was broken in many places. The rings were so badly worn, they had become T shaped with the top part of the T being the part that rode against the cylinder wall and the botton | part was the part in the groove. I had no indication of broken rings, engine ran smooth without smoke.

what motor?

was it new or a rebuild?

had it ever been overheated?

how many miles since rebuilt/new?

Chevy 350

Rebuilt

Not while I owned it.

Unkown milage. It had a pretty good ridge at the top of the cylinders, I actually broke a piston because I tried to hammer it out without reaming the ridge. Then I bought the ridge reamer and pushed out all remaining pistons by hand.

Rings can break for several reasons:

1. Inproper installation
A. End gap too tight. Ring expands and closes gap, making
ring expand against cylinder wall. Ring wears faster than
normal. Ring breaks.
B. Ridge not removed or removed partially. Usually only
breaks top ring but pieces can affect second ring.
C. Wrong ring side clearance, piston expands and puts
squeeze on ring. Ring cannot go into ring groove because
it is too tight.
2. Inproper Environment
A. Engine is overheated and rings gall on wall
B. Engine sits and rings rust to cylinder walls. On restart
rings are unstuck by violent action...like starting engine
C. Detonation

I'm sure the other CHR folks can add more reasons.

With that much ridge, it was just worn out. Piston slap can break rings, too.

All broken rings were top rings. The T shape could be due to odd wear after the rings broke. I'm sure they have been broken for over 10,000 miles. When I first got the truck, it had all of the signs that it had been run at low speeds under light loads a lot, lots of carbon. Well, I like to give it a little gas every once in a while and the ridge was probably low in the cylinder as a result of low speed operation and the rod stretch at the higher rpms was enough for the top ring to contact the ridge.

No need to be empathetic, Denny, I didn't even know I had the broken rings. It's gonna be reincarnated as a more gas milage friendly engine that will hopefully pass smog. I need to find the dumbest inspector in town and take it to him. The one I normally go to will likely recognize the Vortec heads.

thats why i goto the smog guy that puts his car on the machine and passes it as yours... hes a lil more pricey than the other guys tho

I meant to say, you don't have to feel bad. I didn't mean to sound ungrateful for the advice.