# Timing Chain/Belt woes.



## smockrw (Dec 11, 2001)

So the better half and I were driving in the mountains when a barely audible additional noise began to work its way into our awareness. 

Being somewhat cautious with our A6 Avant the timing belt/water pump, tensioner main and cam seals were replaced at 73k, the clock is now at 108, oil changes promptly at 6 months or 10k miles with Rotella T6 or other suitable synthetic. 

So, what is this ticking? sounds like timing chain rattle, being somewhat of a noob with the Audi V6 (my calling is VW 4 bangers and lately a VR6) I thought it odd to hear chain rattle from a belt timed engine, 
other than the noise the engine/vehicle drives fine, oil level is proper (no loss at all) and the idiot oil light is lit only on initial startup (shuts off once the motor fires up). 

I did some research here and online and found that the diesel sound and slap is generally indicative of timing cam chain tensioners, using a scope I isolated the slapping/metallic noise right where it would be if it were the drivers side tensioner so I purchased one and was planning to replace it today. 

So why the doubt now? I pulled the valve cover covers (plastic) and the timing belt covers and saw some evidence of belt shred, I started the motor to double check the sound/location and noticed that there was almost no tension on the timing belt and it was bouncing, to the hand it gives about half an inch but doesn't appear to have skipped a notch or broken a tooth. 

So after reading the above you get my question. 

Looking at the manual it appears that the timing belt tensioner is hydro actuated (as is the chain cam tensioner) 

Would this be a sign of cascade failure; are these parts fed from the same oil galley? 
I hadn't planned on removing/service locking this beast but have started the process of removing the front end but am worried about what I will find, could this be a sign of oil pump failure (both are oil pressure driven) a plugged galley (no apparently oil leaks) is it possible that one failing would cause the other not to work? I already have the cam chain tensioner and will most likely replace it, are there any tests or visual indicators that the timing belt actuator has failed? 

Any advice on this would be appreciated thanks, 


Randall


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## tryin2vw (Dec 30, 2006)

The timing belt tensioner on my 99V6, 30V is not fed from any oil pressure. The tensioner is self contained. 

You may need to remove the front end to find one of the two rollers, (Idler or tensioner) has a bearing that has failed. Idler roller failure is what caused the TB on my car to fail. The timing belt became floppy and jumped time, stripping teeth off the belt, trashing two cylinder heads.


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## smockrw (Dec 11, 2001)

*Update...*

Indeed, hydro in this case does not mean that its oil fed, got down to the cover on the crank pulley 
(removed the serp pulley but not the timing) and found that the last person to have it off put the plastic cover around the crank pulley on in a hurry, it was binding on the tensioner, pulled it off and the belt snapped back to its expected tense state. Kind of stinks that I had planned on doing the cam chain tensioner by pulling one cam and not entering 'service lock' but its good that the cam chain tensioner failed if it hadn't the timing belt would have failed prematurely. I suppose this is anecdotal but the last person(s) to have it apart to this level were Audi tech's :screwy: 

Thanks for the reply. 

Randall


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## tryin2vw (Dec 30, 2006)

Are you sure the CCT has failed or has the ECU tried to adjust the timing to compensate for the timing belt issue? 

Doug


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## smockrw (Dec 11, 2001)

*No, not 100% certain*

When I got this all apart I notice that the CCT was binding (the tool to compress it nearly broke during the removal process). The loose belt was not making making the chain noise in fact it was barely audible over the noise that I was hearing (clack clack clack like a diesel) which went away when I replaced the part. I am still a little worried about this though as the manual for the ATQ/V6 states 16 pins between intake and exhaust, when I set it this way I found that no matter what I did I couldn't get the cams to line up with the cap/timing marks, moving the intake cam one tooth allowed for both to match up as they were before I removed the old part, doing some research on the net I have seen many complain about this fact (14.5, 15.5 and 16 pins all being noted as working for some).

Visual on the old CCT showed no evidence of bore wear, but the bottom shoe had deep enough grooves that I am convinced it would have come apart sooner than later, if it were sludge I would expect to find something in the bore or it should have cleared when I seafoamed it.

So, after doing all this and getting the car back together I've ran nearly 200 miles with the engine getting quieter with each trip, figured it was good, returned it to its rightful owner (my better half) and during a trip downtown it tripped a MIL, checking with the trusty code reader I got a P0021 (left bank, cam timing advanced) which now has me worried about, engine is running fine, no misfires (audible or reported via ODB2) I reset the code and it hasn't triggered in two days of driving.

Did I miss something?


Thanks


Randall


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## tryin2vw (Dec 30, 2006)

Sludge is not generally a problem with the V6.

Put the car back at TDA with the VC off and recheck the timing mark match-up on the cam bearing caps. After running for 200 miles the CCT should have more than pumped, and the marks should now align properly. If they are off, then the cam needs to rotate a tooth one way or the other.


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## smockrw (Dec 11, 2001)

*Will check.*

As I used the timing belt/TDC on crank and cam cap mark on exhaust as a hard ref I would need to move the sprocket on the intake, I certainly hope I don't have to but once I get the cooling out of the way its easy enough to do without 'service lock'

Thanks

Randall


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## O_o (Nov 12, 2009)

smockrw said:


> As I used the timing belt/TDC on crank and cam cap mark on exhaust as a hard ref I would need to move the sprocket on the intake, I certainly hope I don't have to but once I get the cooling out of the way its easy enough to do without 'service lock'
> 
> Thanks
> 
> Randall


Since it's throwing a code, you can check the cam angle if you have access to a VAG-COM.


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## smockrw (Dec 11, 2001)

*well....*

no access to VAG-COM, just a generic reader, its thrown the code once and reset, hasn't thrown it again,
starting to question my sanity  I know 1 tooth off on the timing is bad but is one tooth advanced on the intake going to lead to a situation where I could have contact? or just misfires? as I said earlier its running great, fuel economy is better than ever I am more worried about whether I should drop everything and tear the car back down or if I can wait for a second code to be thrown before taking it apart.


Thanks

Randall


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## O_o (Nov 12, 2009)

One link off on the timing chain won't slam a valve. If the position sensor is on the intake camshaft, then it would definitely have thrown a code by now if it were off. I honestly don't remember which side it's on, but it doesn't make sense for it to be on the exhaust camshaft, or the VVT wouldn't have any feedback.


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## tryin2vw (Dec 30, 2006)

If it is running great and it is not throwing any codes, then you can probably wait. One tooth off will not cause the piston to hit the valve, just misfires due to low compression due to the timing being off. 

If you have a compression tester, you can verify it that way as well. Check both banks to verify the numbers. My compression ran in the 190-200PSIG, but I have heard of them as low as 140's without issues. 90-120PSIG is not good.


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## Slimjimmn (Apr 8, 2006)

the code means you put the cams off one tooth.


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