OK to chamfer top piston ring?

[berniedd]

A friend's late '90s Honda needs a ring job because of a stuck oil ring, and the stuff he's used in his oil haven't cut it loose. He thinks the pistons can be removed from the bottom end without needing to pull the head off, and thereby save himself a lot of work. I opined that if there's a ridge at near the top of the cylinder bores where the old compression rings don't reach into, the new, unworn topmost compression rings might get damaged (and possibly the pistons as well) as the ridge (with smaller diameter bore, even if it's only microns less in size) squeezes 'em. I suggested he might get around the potential problem if he files off a small chamfer on the outer, upper edges on all his new #1 piston rings. What do you guys think?

 

[spasm3]

i would not file anything on a ring except to obtain the correct endgaps.

 

[The_Jeff]

Lucky guy. I've done saturn ring jobs and the head has to come off, as the rings jam in the liners coming out the bottom.

But, I haven't run into any ridges.

So long as it's still running, go on a nice spirited drive to redline or beyond

as the con-rod will stretch a micron and you can let the old rings work on that alleged ridge.

 

[The_Eric]

Originally Posted By: eljefino
Lucky guy. I've done saturn ring jobs and the head has to come off, as the rings jam in the liners coming out the bottom.

But, I haven't run into any ridges.

So long as it's still running, go on a nice spirited drive to redline or beyond

as the con-rod will stretch a micron and you can let the old rings work on that alleged ridge.


I agree. Flog it first, then tear it down if needed. Also every engine I've been into, the pistons will not go out the bottom of the block.

 

[chad8]

never file rings. you will remove the hardened chromium edge. I would pour seafoam or berryman cleaner into each cylinder through the plug holes and let it set 24 hours.The next day Crank the motor a couple times to remove the liquid and replace spark plugs. fire it up . I would also use a dose of either auto rx or mmo in the oil beforehand.
You need a good strong solvent to free stuck rings. Remember that it might be worn valve guides or seals and not rings. Depends on symptoms.

 

[Astro14]

I think your friend is mis-informed.

I can't see how you can get the pistons out through the bottom...Further, if you put new rings in - you need to cut the ridge and hone the cylinder so that they will seat. Both require the head coming off. Fail to complete those steps and the new rings will let it burn even more oil than it burns now...if you don't crack the ring lands in the pistons from hitting the ridge. File the rings? no way...you'll destroy the temper, the effectiveness and the compression in the engine...

My dad used to say: it's the cheap man who spends the most...don't try and cut corners on this.

 

[Johnny248]

how can you remove and reinstall pistons through the bottom??? Compressing rings seems pretty impossible through the bottom of a block.

 

[Chris142]

The pistons will not come out the bottom! He must remove the head. If there is a ridge that needs to be removed he will need to rent a ridge reamer to remove the ridge so that the ring lands don't get damaged when removing the pistons and so that the new rings dont hit the ridge.

 

[MarkM66]

Originally Posted By: berniedd
He thinks the pistons can be removed from the bottom end without needing to pull the head off, and thereby save himself a lot of work.


Removing the engine and doing a proper rebuild would "save himself a lot of work."

Even if it's possible, doing all that work on your back would be a challenging job with sub standard results.

 

[onion]

If this guy thinks he's going to pull pistons out the bottom of the engine... then I would strongly discourage him from taking said engine apart unless he has somebody with lots of experience and tools willing to hold his hand through the whole process.

Otherwise he's going to waste lots of time and money... and ruin his engine in the process.

 

[mechtech2]

If the crank comes out, he may be able to get the pistons out the bottom.
But so what? You can't get them back in that way.
Filing the rings is ludicrous.

Yank the head. Why would you avoid this?

 

[Robespierre]

Hasn't anybody here ever read The Grapes of Wrath? Apparently you can pull the piston out the bottom of a 1920-something Hudson Super Six engine, at least according to the Steinbeck manual.

I tried pulling a piston out the bottom once, from a 153 I-4 Iron Duke with a cracked block. It seemed like a good idea at the time. First I removed the crankshaft, because with it installed there was nowhere near enough room. Unfortunately, the main bearings were too close together, and I couldn't get the piston out. I suspect that you would run into a similar problem with just about any modern engine.

 

[onion]

Originally Posted By: Robespierre
Hasn't anybody here ever read The Grapes of Wrath? Apparently you can pull the piston out the bottom of a 1920-something Hudson Super Six engine, at least according to the Steinbeck manual.



I always thought that was strange. Never knew whether to attribute that to the fact that I've never worked on an old Hudson engine... or the fact that Steinbeck was an author rather than a mechanic. But having lived in Kansastan for several years now- and having read quite a bit since the Grapes of Wrath- I can say that there are several historically inaccurate factoids within The Grapes of Wrath (not the least of which is that the town the Joad's are from was hundreds of miles from the 'dust bowl').

So I'd take that with a grain of salt.

 

[meep]

regardless of rings, upper piston travel will remain the same... so an old ridge with new rings shouldn't cause trouble.

revving the engine UNLOADED will cause more upper-end travel than loaded (less pressure up top, which is why ecus have lower rpm limit in N in modern cars).

Regardless, if it's so worn that there's a ridge, a newer set of rings isn't going to fix the problem.

Ring job typically comes with bore and hone in my book... an actual rebuild.

I 2nd the MMO or seafoam soak.

I agree with above-- even if you can get the pistons out from the bottom, they aren't going back in.

Suggest pricing an AAP rebuilt block or even a low mile 'yard motor.

M

 

[mechtech2]

I have worked on a few small old 2 stroke engines that had the head integral to the bore.
The piston went in from the bottom, but the bore was chamfered for this.

BTW, revving an engine loaded or unloaded is about the same.
Why?
Because it is the UNLOADED exhaust stroke that the max load occurs a the rod and bearings.
This is the same loaded or unloaded - it is RPM dependent only.

 

[Scott_Tucker]

The pistons absolutely will not come out from the bottom (in one piece at least). If you replace the rings you must at least use a dingle ball hone to 'break the glaze' and provide a surface for the new rings to seat against.

Sounds like this guy needs a mechanic.

 

[Slick17601]

If he's not going to remove the head, he would be better to leave well enough alone.

 

[mechtech2]

If the crankshaft is out, then the pistons probably could come out the bottom. Maybe even if it is in, in certain positions.

 

[spasm3]

He has got to come back and let us know how this works out! Even if you got the pistons out the bottom, how are you going to have room to use the ring compressor to get them back in? On the ridge issue, i've used a ridge reamer and screwed up the top of the cylinder, had to over bore. I would not use one again, id use a stone in a grinder carefully or if i'm going to use new pistons, get a bigger hammer and knock them out from the bottom .

 

[onion]

They won't fit out the bottom.

MAYBE on an old tractor engine or something... but not on any modern automotive engine. It'll never happen. Not enough room.