JHX

Never seen this. Bought a car with a L98, 355 motor of unknown origin. Rebuild is obviously not very old. Rough idle. Failed compression check on #8 W 70psi.

Remove heads, pull pan, pull piston, and the rings are stuck FIRMLY in their grooves?

Possibly Related:

1) The car sat for an indeterminate amount of time before I bought it.

2) May have had overheating issues in the past. (Fan problems when I purchased it, was wired to a switch.)

3) Huge amount of water in the fuel when I got it due to leak at the filler neck.

Ever seen this?

JHX

PS: Beat one of the comp rings off. Groove is fine and clean? Severe carbon deposit on inner circumference of piston ring only?

sofakingdom

iTrader: (1)

If the ring got stuck and you used force to get it out, the piston is probably ruined.

The sides of the ring, and the mating surfaces of the ring land of the piston, are VERY tight-tolerance sealing surfaces. Scratches, warpage, etc. will prevent the rings from sealing there, and the inevitable result is MASSIVE blowby.

Too bad people feel the need to DESTROY their cooling systems like that, instead of maintaining them properly. Un-do that; get rid of the switch; get the cooling system back working right again.

Sounds like it's time for a tear-down and rebuild of that short block, with new pistons and rings. No telling what else is screwed up about it. No sense putting it all back together and discovering it SUCKS.

Tank needs to come off and be boiled out. You'll never get rid of all the problems caused by that water, otherwise.

What heads are on it?

Hope you got it cheeeep?

JHX

I dunno? They aren't real good quality anyway. But it's interesting because it had fluffy carbon deposits behind it and in between, jamming it?

Like sand? I dunno what the deal is with this particular cylinder? The others passed the check, but now I don't trust them.

Already done. It was the PCM, actually. It couldn't see the temp. (Maybe someone grounded the sensor and burned it?)

Probably.. Doggone it.

I put a new rad in it. It did have a bunch of brown, stop leak looking stuff in the OF tank. (Muratic acid cleans that right out, btw. In case anyone else has an issue like this.)

Appear to be stock, Iron 85 Gen 1's

Sorta. 2K. It's a C4. Pretty rough. Bought it for a project and had health problems, never got back to it till now.

Damon

Stuff gets behind the pistons rings because that's how they are designed to seal up- combustion gasses get behind them and push outward on the ring, sealing it firmly to the bore.

It's not the just the mechanical tension of the ring that makes it seal up in a running engine.

If they engine's running badly- overly rich, lots of oil getting in the combustion area, timing incorrect, etc.- all that crap starts building up on and behind the rings. Water in the cylinder isn't going to help, either, as you cam imagine (rust).