Piston Ring Problem

cr@M · Posted: Thu Dec 10, 2009 2:48 pm Post subject: Piston Ring Problem

So i pulled my motor a while back to change the pilot bearing (some should remember that thread) and i took off my heads to see how the engine is doing. Besides a stripped spark plug (#3) and a leaking exhaust gasket (#1) making those two cylinders run hot everything looked fine.

I also pulled a cylinder to see how the rings were and the oil ring was broken in several spots. Checked other cylinders and there were a couple of broken rings.

Went to Bow Wows, got rings for a 1.7, thus my discovery of having 1.8 P&Cs haha, got the right rings, and got ready to tear down. Took the old rings off, broke a ring to clean all the grooves, and started installing the new rings. Everything went in smooth, but as i put in the top compression ring it wouldn't go into the groove. It's just too wide to fit into the groove. I did a test and the beveled compression ring fits into the middle grove just fine and the oil scraping ring (2nd groove) fits into the top groove just fine. So i could swap out the two rings and it would all go together just fine.

According to the Grant instructions and my knowledge i know that's not the correct way of installing rings. However the old compression rings were just flat, no beveling at all, so i guess in theory it could work. I'm kinda out of options since i can't reinstall the old rings. It's either swap the rings or maybe file the rings down until they fit (which I'd rather not do).

Any thoughts?
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1972 Deluxe named Lucidity
1973 Transporter

"He who fights with monsters must see to it that he himself does not become a monster...
when you gaze long into the abyss, the abyss also gazes into you."
-Friedrich Nietzsche
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fusername · Posted: Thu Dec 10, 2009 3:04 pm Post subject:

filing em down wont fix it, there are very specific dimensions going on there. I would reccomend triple checking that you have the right rings in the right places.
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germansupplyscott · Posted: Thu Dec 10, 2009 3:08 pm Post subject:

measure the thickness of the old rings and the new. maybe you are trying to do something like put a 1.75mm ring in a 1.5mm land.
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cr@M · Posted: Thu Dec 10, 2009 3:23 pm Post subject:

Hard to get exact measurements. Looks like 2mm new rings vs. 1.75ish old rings. (EDIT)

Out of curiosity, would a 2.0L motor have slightly wider rings?
_________________
1972 Deluxe named Lucidity
1973 Transporter

"He who fights with monsters must see to it that he himself does not become a monster...
when you gaze long into the abyss, the abyss also gazes into you."
-Friedrich Nietzsche
_________________

germansupplyscott · Posted: Thu Dec 10, 2009 4:25 pm Post subject:

Wildthings · Samba Member Joined: March 13, 2005 Posts: 52550

Rings are pretty generic. You might just take you P&C's down to your local machine shop and let the guys there tell you what you need and get it for you.

SGKent · Posted: Thu Dec 10, 2009 11:36 pm Post subject:

did you have a machine shop check the cylinders to see if they were scratched by the old broken rings.

3 reasons I know that they break

Bad installation
over reved before broken in
detonation
_________________
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" Rolling Eyes

cr@M · Posted: Fri Dec 11, 2009 10:57 am Post subject:

Yeah i think I'm just going to take my piston with me and figure it out at the shop.

The cylinders have a little cross hatching from being honed, but no scratches. Mostly it was the oil rings that were broken. They were the spring style. Those rings were really brittle so i almost don't blame the PO for just putting them in broken (almost).
_________________
1972 Deluxe named Lucidity
1973 Transporter

"He who fights with monsters must see to it that he himself does not become a monster...
when you gaze long into the abyss, the abyss also gazes into you."
-Friedrich Nietzsche
_________________

SGKent · Posted: Fri Dec 11, 2009 1:01 pm Post subject:

rings only break during install when someone doesn't know how to install them.

Try this. Before you do be aware that the edges of rings, expecially broken ones can be like a razor. Take one of the OLD ones and put pressure on it opening it up until it snaps. Pay attention to what it feels like. That is how fragile they are. Rings cannot be handled roughly or they will snap. Most are cast steel.
_________________
George Carlin:
"Most people don't know what they're doing, and a lot of them are really good at it."

Skills@EuroCarsPlus:
"never time to do it right but always time to do it twice" Rolling Eyes


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