Audi Broken Oil Control Rings - Why???

[SonofJoe]

It's well known that the early Audi 2.0L TFSI petrol engines were plagued with massive oil consumption problems.

There's plenty of evidence that engine oil could migrate from the crankcase of these engines back to the intake system to be burnt. I've also seen evidence that oil control rings would plug up with gunk and stick, exacerbating the oil loss problem from below.

Then I saw this video on YouTube...

https://youtu.be/G-WrxAOaWDs

This engine teardown shows that three of the pistons from an 2009 Audi 2.0L have oil rings which have broken into several pieces. I assume this only became apparent when the pistons were removed. Prior to this, I could imagine that the ring pieces were kept in situ in their grooves as a result of tension from the oil control ring spring.

I am genuinely puzzled as to why oil control rings would break in this way? It's clear from the filthy condition of the pistons that this engine has been burning vast quantities of oil. I did wonder whether this might be caused by oil burning related detonation problems causing the pistons to overheat but I'd expect this to cause problems at the top of the piston where pressures and temperatures are at their most extreme; not at the bottom where the oil control rings sit.

I suppose it could be duff metallurgy but it's just a simple piston ring; what's there to break or go wrong?

Anyone out there in BITOG-Land able to throw any light on this phenomenon?

 

[krismoriah72]

You kind of answered it yourself when you said that the rings would plug up and stick. A ring that is travelling thousands of rpms over many miles that is stuck will eventually fail and break.

oil should flow through the lands, grooves, jets, rings and cool the metals and lubricate them..when they are coked off and clogged this cannot happen, so the oil bypasses and the metals become brittle from heating and cooling cycles and break making the problem worse.

 

[JHogan]

I'm a writer with Middleburg Heights Audi in Ohio. And its still a very prevalent problem. Just next week alone we have scheduled 4 2.0 TFSI engines for piston replacement covered under Audi. Out technician alone has done over 800 of these by himself.

 

[nascarnation]

Not sure.
The original Saturn 1.9s plugged oil rings because the piston design did not have the usual drainback holes drilled through the ring belt. But I never saw any broken rings, even at pretty high miles. A lot of them failed due to running out of oil, if you kept them full up they would just keep running.

 

[SonofJoe]

Interesting comments but in my experience it doesn't usually happen like that.

When grooves fill up with soot/varnish/high molecular weight decomposition products/whatever, it's like the entire ring gets 'glued solid' in the groove and sits flush with the lands. There's minimal contact anymore between the ring and the bore so very little by way of friction or distortional stress; if anything, the gunk maintains the mechanical integrity of the ring! If you're running poor oils on some of the industry standard engine tests, you can often see this and then have to record the rings as either bring 'cold stuck' or 'hot stuck'.

What's confusing is that whereas I've seen what appear to be stuck oil control rings from problem Audi's (which explains the oil loss), in industry standard oil tests, it's usually the top ring and very occasionally, the second ring, that sticks. Oil control rings never give problems and received wisdom is they run too cool and are too well lubricated (they sit more or less directly above the oil squirters) to be an issue.

Whatever this is, I'm convinced it's not normal. The video suggests to me that something has induced specific stress points in the oil rings causing them to snap. It must have something to do with the oil loss/burning problem. I just can't figure out what.

 

[Ethan1]

Originally Posted By: JHogan
I'm a writer with Middleburg Heights Audi in Ohio. And its still a very prevalent problem. Just next week alone we have scheduled 4 2.0 TFSI engines for piston replacement covered under Audi. Out technician alone has done over 800 of these by himself.


It's probably not a good idea to give your name, your employer's name, and your job title... then say bad things about the parent company's products.

 

[SonofJoe]

Originally Posted By: JHogan
I'm a writer with Middleburg Heights Audi in Ohio. And its still a very prevalent problem. Just next week alone we have scheduled 4 2.0 TFSI engines for piston replacement covered under Audi. Out technician alone has done over 800 of these by himself.


Hi. I know Audi have stepped up to the plate and paid to get these problematic engines fixed. However they have been extremely tight lipped as to what the original cause of the problem was. The 'bad batch of piston rings' excuse does not 'ring' true to me. They're piston rings for Heaven's sake! Unless you made them out of plasticine, what could go wrong with them?

I think what's always concerned me is not Audi's problems per se (after all this is now in the past), it's what lessons this might hold for the future of engine oils in general; particularly high Noack oils which will in theory still be allowed in GF-6 and oil-induced knock/detonation effects.

 

[edwardh1]

Does toyota have a lot of this problem? something went wrong.
VW in 1979 put bad valve stem seals in many rabbits.
They wold not change the spec until 5 years later when they sued by some US federal regulatory arm, and forced to repair the engines which burned a qt every 200 miles and locked up on freeways, causing wrecks.
German engineering - not responsive

 

[Falken]

My guess would be the rings aren't designed correctly.

If the ring gap is too thin, and they touch together under high RPM, they ring will flex and eventually shatter.

It is a design issue IMO, not "stuck rings".

I'm sure the revised rings have a larger gap by a few thousandths of and inch.

 

[PeterPolyol]

That style of oil control ring is probably not the finest design and it looks very thin. The traditional three-piece rings never fail line that.

 

[SonofJoe]

Originally Posted By: Falken
My guess would be the rings aren't designed correctly.

If the ring gap is too thin, and they touch together under high RPM, they ring will flex and eventually shatter.

It is a design issue IMO, not "stuck rings".

I'm sure the revised rings have a larger gap by a few thousandths of and inch.



That's a really interesting point. It could potentially explain the breakage but it doesn't jive with some other things that I think I picked up correctly. First, in the US, when this problem first hit, some cars did get fitted with brand new rings and it didn't fix the problem. Second, in the UK, when Audi fix these bad engines, they don't just replace the oil rings with ones with a bigger end gap; they replace the entire piston assembly, including all new rings and the con-rods. Curious. Why change perfectly good con-rods and presumably the bottom end bearing to when you don't have to? The only reason I could think of is if the new pistons were 'different' in some way, possibly longer maybe to accommodate thicker rings, because that would probably necessitate a marginally shorter con-rod. BTW, this solution stops the oil loss problem dead in it's tracks.

It begs the question, were the original oil rings too thin and of insufficient mechanical integrity? This, coupled with the original ring gap possibly being too small, might explain both the original oil loss problem and shattered rings. Fascinating...

 

[Silk]

Cast iron rings usually break from detonation, not really likely on a modern engine with knock sensors. I haven't seen a one piece cast iron oil ring with expander for a long time, most these days are stainless rails with an expander.

 

[milkboy]

Originally Posted By: JHogan
I'm a writer with Middleburg Heights Audi in Ohio. And its still a very prevalent problem. Just next week alone we have scheduled 4 2.0 TFSI engines for piston replacement covered under Audi. Out technician alone has done over 800 of these by himself.


This is impossible ; it is common knowledge that German manufacturing and engineering represent flawless perfection.

 

[andrewp1998]

My sister in laws 2006 a4 ran out of oil with only 44k on it back in 2012. Black soot in tailpipe and blue smoke. She is still in denial !!

NUTS

 

[edwardh1]

what did audi CHANGE, from the year before these problems started???

 

[BrocLuno]

Originally Posted By: Falken
My guess would be the rings aren't designed correctly.

If the ring gap is too thin, and they touch together under high RPM, they ring will flex and eventually shatter.

It is a design issue IMO, not "stuck rings".

I'm sure the revised rings have a larger gap by a few thousandths of and inch.


Bingo - broken rings are almost always fitted too tight and they end-lock and expand to hard against the cylinder wall when hot, stick and break. I have never seen a broken ring that was loose fitted ...

I'd suggest a "competition" fit end gap on the replacement rings and it will run a zillion miles

My bet, they were trying to control oil to aggressively with low tension rings to make their air pollution/mileage goals for sale in the USA/Calif. Wrong way to do it ...

 

[Jetronic]

Originally Posted By: milkboy
Originally Posted By: JHogan
I'm a writer with Middleburg Heights Audi in Ohio. And its still a very prevalent problem. Just next week alone we have scheduled 4 2.0 TFSI engines for piston replacement covered under Audi. Out technician alone has done over 800 of these by himself.


This is impossible ; it is common knowledge that German manufacturing and engineering represent flawless perfection.


The engines are perfect, but the owner is not using them correctly.

 

[JHogan]

Originally Posted By: Ethan1
Originally Posted By: JHogan
I'm a writer with Middleburg Heights Audi in Ohio. And its still a very prevalent problem. Just next week alone we have scheduled 4 2.0 TFSI engines for piston replacement covered under Audi. Out technician alone has done over 800 of these by himself.


It's probably not a good idea to give your name, your employer's name, and your job title... then say bad things about the parent company's products.
I mean it doesn't really matter, I'm not talking bad about the brand. 90% of our customers have common knowledge of this. It's not like we hide the problem from them. It shows up on their data sheet when they come in for service if its possibly affected or not.

 

[JHogan]

Originally Posted By: SonofJoe
Originally Posted By: JHogan
I'm a writer with Middleburg Heights Audi in Ohio. And its still a very prevalent problem. Just next week alone we have scheduled 4 2.0 TFSI engines for piston replacement covered under Audi. Out technician alone has done over 800 of these by himself.


Hi. I know Audi have stepped up to the plate and paid to get these problematic engines fixed. However they have been extremely tight lipped as to what the original cause of the problem was. The 'bad batch of piston rings' excuse does not 'ring' true to me. They're piston rings for Heaven's sake! Unless you made them out of plasticine, what could go wrong with them?

I think what's always concerned me is not Audi's problems per se (after all this is now in the past), it's what lessons this might hold for the future of engine oils in general; particularly high Noack oils which will in theory still be allowed in GF-6 and oil-induced knock/detonation effects.
Yes even the technicians aren't exactly sure what the true issues are. They do two different stages of testing to determine if the engine needs pistons. All they do is submit said data to Audi and they make that determination, which I've yet to see one not get approved. They've even approved some that weren't part of the warranty extension...All I know is every one of these engines I see that have this issue have one thing in common. That is that there is an irregular amount of sludge and carbon build up, both in the top of the head and the pistons themselves.

 

[edwardh1]

again, what changed from the year before?