more on compression woes - passat 96 vr6

Well now, got the compression numbers on the vr6 passat that gave up the ghost a couple of weeks ago. Cyls 2,4 and 6 are all around 180 psi (cold engine). Cyls 1,3 and 5, O psi, 60 psi, and 0 psi. > > Bent valves on 3 and 5? Skipped tooth on timing chain? blown timing chain tensioner? All of the above? Any bets before I take off the valve cover? >

And JRE responded

Sounds like a cam stopped. Ugly if it's an interference engine. A >couple other possible causes: Sheared woodruff key or broken (or >backed-out) dowel on cam sprocket, broken camshaft (esp. if engine ran >low on oil).

And JRE takes the prize on this one. Finally got around to pulling the valve cover and sprocket cover. Rear sprocket had come completely undone and the dowel had backed out to the sprocket cover, and the woodruff key had sheared. The thing was wobbling all over the place. I'm amazed that I got any compression at all on cyl 3.

The thing I'm wondering is how this happened in the first place. Since I've had the monster (2 years) it's been really well-cared for. Plenty of oil and coolant...etc. One weird thing - I found broken pieces of a timing chain tensioner inside the upper sprocket cover, but the tenisoners themselves appear fine. I wonder if maybe somebody replaced the tensioners at some point and rebuilt the head, but didn't torque the sprocket properly...? Freaky.

Anyway, next weekend I get to see how bad the valves look.

Reply to
starburst
Loading thread data ...

Glad you are finding out what is wrong. Sorry you actually have damage, but you suspected you would find it. How many miles on the engine? Would it be wise to replace entire engine or you have time to repair it?

Remember to Take Pictures!!! BTW are you on the vwpassat group on yahoo?

later, dave (>

Reply to
dave AKA vwdoc1

I can't afford to replace the whole engine, and it's only got about 95k miles. This is pretty pathetic performance if you ask me. The head's a goner, for sure, and I've got a line on a replacement at a junkyard. I don't have the time to rebuild the head that's in it. My big concern is that the pistons got fried. We'll see.

We're down to one car (the 89 jetta, aka Miss Reliable), but what's a body to do? I can't afford to have somebody fix the passat - it could likely cost more than the value of the car, and I'm pretty pissed off at it. It's like being married to somebody you don't like, but not bein' able to afford to get divorced.

I've been there a few times (last year), but most of the discussions seemed to revolve around cosmetic stuff - color combos and boom boxes and such. Vortex's tech/vr6 group is pretty good, though. - C

Reply to
starburst

Thanks I will have to check out that Vortex's tech/vr6 group! ;-)

The conversations we have had on the vwpassat group on yahoo was about a noises/problems with some of the engines. I heard noises on a '01 Golf GTI with the VR6 engine, but the owner only complained of the Engine check light coming on before the emissions test. The original owner only had 56K miles on it and the noise was emanating from the camshaft area. It was caught "early" but still would have been a $3300 bill at the dealer. Owner was able to prove that regular oil changes were done and the warranty repair was just approved. Currently it is still at the dealership as parts supposedly need to be ordered for the engine.

In your case did you hear any noises before this problem occurred? I will assume that you are not the original owner that possibly had the 100K miles or 10 year warranty on the powertrain. Maybe the original owner did not maintain the oil change intervals. OR maybe the oil formulations have changed and that caused problems in engines like in both of these VR6 engines.

later, dave (One out of many daves)

Reply to
dave AKA vwdoc1

Thanks dave. On further looking, it appears that the upper tensioner blew. I had assumed that since the tensioner was metal and in one piece it was fine, but noooo. It used to have that piece of phenolic riveted to the face, and that's the source of the chunks I've been finding.

I posted links to pictures of the sprocket, tensioner pieces and tensioner here:

formatting link
Seems like pretty crappy engineering to me. It's great that you don't have to replace the timing belts on these cars, but to replace the tensioner I need to remove the transmission, which is so much of a bigger job. And there's less than 100k on the engine.

Oh well.

Yes, she'd been making a rattley noise before it went, but I just figured it was another form of VW valve ticking, you know?. Can't answer to earlier maintenance.

Chris

dave AKA vwdoc1 wrote:

Reply to
starburst

Thanks for the pictures and the link. Looks like there were problems and I guess when one hears a noise from the engine that does not sound healthy, it might be good to check it out. ;-)

Let us know your progress. I probably would have done the '01 VR6 timing chain replacement but the dealer is doing it under warranty.

good luck! later, dave (One out of many daves)

Reply to
dave AKA vwdoc1

As I posted on vortex.

From looking at your pictures the engine looks like it has a lot of crud inside it. Does the camshaft turn that the gear is removed from? You may have seized it if oil pressure when low. Pull the oil pan and take a look. BTW, you will have bent valves and you "must" figure out why the key sheared off!

Reply to
Lost In Space/Woodchuck

Thanks on both spots. Thing is there was plenty of oil in the car at the time that the car died. She'd been losing about a quart every 800 miles or so, mostly through the rear main seal, but I was always on top of it and had just changed the oil a week earlier. The crankcase is still full. I just went out and tried to turn the cam and it isn't budging. Why would the cam seize if there was enough oil? And the engine had just gotten up to operating temperature when it blew. In your experience (and I know you've got lots) when the chain tensioners break at speed, what other damage do you see? Bent valves for sure, but would the seized cam be normal?

I'll take the head off next and have a look. Thanks - Chris

Reply to
starburst

It has been my (unfortunate) experience that if an engine is eating oil at the rate you describe, it is not long for this world even if you determine and identify the largest single source for the leak. It is that "mostly" that does it for me. I have nursed a Mercedes TD engine through about 10,000 miles under those conditions, but ultimately the engine seized. As i knew it was coming and as the engine had over 300,000 miles on it, I was both prepared and not upset with it.

Dave has it right. At least a new or rebuilt head, and make sure that the cylinders have not been bunged. Furthermore, you need to check the bottom end as well, the main bearings may be compromised if the oil was somehow contaminated (shavings, ground metal, sucked-in coolant or whatever) and that contributed to the failure.

With respect, this may be the time to scout the junkyards for a rear/ side collision VR6 engine and contemplate a heart-transplant if you cannot afford to do it from a rebuilding house.

Peter Wieck Wyncote, PA

Reply to
pfjw

just because the oil is full doesn't mean it's getting to the parts that need it. The next step into remove the oil pan and see if the pump pick-up is plugged and to what degree. Post a picture so I may take a look.

Reply to
Lost In Space/Woodchuck

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.