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Discussion Starter #1
Need some input on this issue.

Appreciate your help in taking the time to read.

2004 V8 bought several months ago with ~100k miles...usual issues initially, such as dead diaphragms on the intake, stuck plastic arms, vacuum leak from same general location. Chain rattle for 2 sec upon cold start, which seems to be the common issue and even described as normal in the TSB, as the owners know. That's why I didn't worry about it too much. Slight lifter noise/tick which also seemed not a big deal for the mileage.

Changed oil and air filters, drove the car as is for at least a months, with some harder driving when needed on the tough NYC roads. No issues with the pull or the drive characteristics.
Finally got to the timing belt job which was done by the trusted shop with a relationship over 7 years with all my cars. The guy doing the job is a very knowledgeable mechanic with deep knowledge of the european cars. Changed the plugs along with the timing belt to Denso NKGs.

Picked up a car after the work, and the engine was smoother than before at idle, felt great, just purring , with same 2 sec chain noise upon cold start. Drove the car home for about 15 miles both street and hwy...everything felt great and smooth. Parked overnight.

Woke up started the car and it immediately started idling very rough with the check engine flashing, then after a minute it stopped flashing and the roughness got slightly better...shaked like a diesel with loud lifter noise.
Drove it to the mechanic staying under 1.5k RPM, since the CEL wasn't flashing any longer. Hoped to place blame at the plugs.

Diagnosis:
Misfires on left bank. Driver side chain slipped a tooth in timing. With valve cover open, the tensioner plastic guide is disintegrated. Left side of the engine is not holding compression with camshafts at TDC. Currently taking off the cylinder block to see if there's any damage to the cylinders/rods which would basically qualify for an engine replacement.


Now the question of the day.
Is this just a crazy coincidence and awful timing(pun intended), or could the timing belt job somehow affect the catastrophic failure on the driver bank leading to the timing skip? I am not THAT mechanically knowledgeable to make accurate assumptions, except that some tighter tolerances, less slack or some kind of a seal damage that resulted in the failure. Obviously the shop states there is no direct connection to the timing belt job, but I wanted to get some second opinion on this.

If you read all the way through, I certainly appreciate it, as well as any input you may provide.
 

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As your V8 has a timing belt and not a chain, I'm confused by references to a chain.
 

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Which parts were replaced and which parts were NOT replaced as part of the timing belt job?

Did you buy the parts or did the mechanic source the parts?

The reason I ask is there are a few possible failure points :

1. Engine was not timed properly when belt was reinstalled
2. Loss of tension in the system
3. Broken tooth on belt

Obviously part of putting a new timing belt on involves checking timing, tension, etc.

If you have known the mechanic for 7+ years I think you are entitled to ask some HARD questions.
 

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Discussion Starter #4
As your V8 has a timing belt and not a chain, I'm confused by references to a chain.
Timing belt VS Camshaft chain in overhead Cylinder head.
00 2000 Audi A6 C5 4 2 Driver Side Engine Cylinder Head | eBay
Picture shows the chain on the right(engine front), where the tensioner in the middle controls the slack in the chain.
The exaust camshaft went out of alignment with the intake camshaft by one tooth of the gear.

Which parts were replaced and which parts were NOT replaced as part of the timing belt job?

Did you buy the parts or did the mechanic source the parts?

The reason I ask is there are a few possible failure points :

1. Engine was not timed properly when belt was reinstalled
2. Loss of tension in the system
3. Broken tooth on belt

Obviously part of putting a new timing belt on involves checking timing, tension, etc.

If you have known the mechanic for 7+ years I think you are entitled to ask some HARD questions.
Timing belt kit with water pump from Gates, Behr thermostat, accessory belt Gates, spark plugs Denso NGK.

All parts sourced and brought in by me.

1.Timing was done correctly I assume, as the tech did check the timing through the computer after completion. In addition the engine worked perfectly fine and noticeably smoother than before (or so it seemed). The skip in timing happened I am guessing on startup the next morning, as it couldn't have happened overnight with the engine off, and it worked great with no CEL the previous day up to being turned off.

2.Loss of tension in the camshaft chain in the cylinder head is obvious, as the plastic guide of the tensioner is gone, but was it that way for a long time before or not no one knows. The issue is why did it decide to disintegrate all of a sudden and did it work fine in the same condition(no plastic guide) all this time prior to the timing belt job.

3.I assume that he had enough experience to check the brand new parts for the possible defects, which are unlikely in themselves.

Please help me find a connection between doing the timing belt job and the camshaft chain skipping a tooth the next day. Why didn't it happen right away or before getting home?
Oil level/pressure?
Accessory belt connection?
Where is the cam position sensor's role in all this?
 

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If you read thru the v6 timing chain problems, the V6 have the same plastic guide and it fails all the time. If I have to hazard a guess, the plastic guide was about to fail no matter what was or was not done. Would also appreciate an update.
 

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Discussion Starter #8
Driver side cylinder head replaced with a used similar mileage assembly. Both tensioners and their chains replaced with German aftermarket units as the oem cost is unjustifiable. Full gasket job done and repaired the intake vacuum pumps while at it. New coils and battery added.
Issues encountered:
A loud whistle from the air intake, which turned out to be a leak in the middle, where the gasket set from reinz wasn't sealing properly. Most likely to a slight misalignment due to the new cylinder head which I don't know the story from. An oem intake gasket set with additional silicone for impact got rid of the leak.

Timing between the belt and the cams as well as the chain timing on each cylinder head was done around three times, as the mechanical timing looked spot on, while the passenger bank showed camshaft codes and idled a bit rough. In the end the cam timing was movedover by a tooth and the engine worked smooth as silk. They said it was neither intuitive nor proper per the markings but it worked.

Remained with the issue of MIL on with the camshaft intermittent signal codes. Played around with camshaft sensors and in the process of elimination and checking the magnets inside the heads, the senior mechanic meditated on it for a week and got the answer from the ether, that it most likely is due to the tensioners, as the sensors only throw codes after about 3000 rpm. I decided it was fair game as is and not an issue for me.

No pressure codes or issues. No misfires. Absolutely no chain sounds from a cold start! I would seriously advise anyone like me who checked all the TSBs etc where it is noted by VW as normal, to open the heads up and check everything. My engine works smooth and quiet and I am assuming the corporate just avoided doing an expensive recall on all these engines. When I had failure on that faithful day, the exhaust camshaft skipped by 60 degrees. That is a catastrophic failure and you shouldn't operate as I did, but no further damage except for marks on the short block pistons.
Oh and the ticking that I had which sounded like lifter noise at low rpm is no more.

Was that a detailed enough follow up? :)
 

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thank you very much for the detailed answer :)
and could you share the link or the brand of the chain tensioners you bought? thank you
 

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Discussion Starter #10
eBay seller deutschepartsusa. Current listing shows manufacturer as OEMQ, but I think it was different one when I bought. Best to inquire directly with the seller.
 

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Wonderful follow up. A big thank you in behalf of everyone on Club Touareg.

My only regret is that you had to go through all that for a stupid piece of plastic! :chainsaw:
 

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+1 i have gathered so much useful info and docs about chain tensioner gasket replacement that if i will get all the tools i think im gonna do the job myself :) once again thanks to some great guys here who helped me on this subject,
one more thing bothers me about this job is how to take off and put back on the camshaft oil seals :( it also needs special tools :( one for taking it off and another one to put new one in :(
 

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Discussion Starter #14
Bump for the knowledge base archives and to help anyone in the future.

Decided to finish up the engine job completely and get rid of the Check engine light, having found an excellent specialist. Car is being worked on as we speak. The basic symptoms left over from the previous posts are the slight hesitation on RPM off full stop, MPG 10-11, and ever so slight vibration at idle developed over time(or I have not noticed it originally).
Codes are Implausible signal Over Retarted on both banks...Guess what.....
timing off on the passenger side camshaft timing chain....AND....WAIT FOR IT....
chain tensioners are backwards, driver side on the passenger head, and vice versa...
excellent job from the guys who did the last job huh?

I've got confirmation that there is no longer any codes about this issue, but the car is still getting some maintenance done, so haven't had a chance to drive it yet.

So thankful that it isn't more complex, such as non-oem tensioners, oil pressure issues or crankshaft pulley keying...

Hope my story helps someone. somewhere.
 

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Thank you for the update. Hope all goes well from now on.
 

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O ....Bother .... wonder when my plastic b*llshit will go.

This is what ultimately got Alex Gee
 

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Discussion Starter #17
Don't have enough posts to reply to a PM from schossow5.

If you read this thread, then the answer is no you don't need an engine dropped for cylinder head replacement. I need one or two more posts and should be able to reply to your further PMs directly...or you can revive this thread if you are having a similar issue and I will reply publicly.
 

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Thank you psycho,
Hopefully I'll get to it this coming week. I scoped it last night and I've got bent center intake valves on all 4 right bank cylinders. Luckily used heads aren't too expensive.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #19
I got a used head from an A6 I think with all internals for a couple of hundred WITH the OEM chain tensioner.....

If your vehicle warrants it and you plan on driving it for a while, then open up both heads, replace both tensioners and chains and consider yourself set.....you will need to get a set of new head bolts and full head gasket sets, as well as be careful the timing between the heads and the timing belt are done properly after. Don't go for OEM, I used a set off Ebay that's mentioned in the thread and here I am driving on it just fine still. The difference in price is horrendous, just don't go by the absolute cheapest off Ebay......

I can attest that in today's day and age, there is no point of going after OEM for used older cars for most parts. I replaced a mass airflow that's OEM at 150+ with a $20 chinese from Ebay....the car is just fine.....it dies - I will get another one. There price gaps are so wide now, that it is cheaper to get 3 replacement sets of most non-critical parts, instead of one OEM set.

Good luck!
 

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I totally agree with the oem vs aftermarket for many parts.
I actually thought it was just the tensioner on the RH side so I ordered one from Europa parts. I Called the dealer and they'd go down from $845 to $675, I said thanks but no, I told the parts guy I could get both sides for $275 on Amazon.
I couldn't believe it when he told me to beware of some of the really low ball sellers like the one I quoted, and he told me about Europa parts...Lol. He's alright in my book.
After I replaced the RH side tensioner and it ran really rough, I did a compression test and realized my problems might be bigger, which were confirmed last night when I scoped the cylinders.

Did you replace the intake gaskets as well?
Also, is there anything else you'd consider replacing while the heads out?
I'm thinking of replacing the oil check valves under the intake valley cover.


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