# ATQ - suspected timing chain tensioner bad



## vtraudt (Mar 1, 2010)

Car is 2002 Passat, engine code (replace by one of the previous owners) is ATQ.

Previous owner found plastic in oil pan, took to local independent VW shop. They said the timing chain tensioner/adjuster is bad.
Car runs rough.
Found a whole bunch of codes (saved and erased; haven't checked which are coming back).

a) what are typical symptoms of bad chain tensioner?
b) how can I determine IF a tensioner is bad?
c) if bad tensioner, how to determine which bank/side?
d) what would a compression test on all 6 cyl tell?
e) what would a leak down test on all 6 cyl tell?
f) on my 2.7T, I was able to check the cam timing, and any timing adjustment done by the ECU with VAGcom (forgot what measuring blocks, but think 90-93 or so). How (if at all) can VAGcom be used to diagnose and narrow down?


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## kirk_augustin (Jul 21, 2012)

*Easy to tell bad tensioner*

The timing chain runs between the camshafts in each head, with one cam powered by the external timing belt. The only plastic that can fall into the pan is the slipper. And you can easily see which slipper needs replacement by taking the cam covers off.


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## kirk_augustin (Jul 21, 2012)

*EAsy to replace*

I forgot to mention how easy it is to replace the chain tensioner slipper as well.
It does require a small special tool that you can buy at any independent WV parts supplier for $15 or so, but then you just use the tool to compress the tensioner, and you can then remove or repair the tensioner as desired. Takes 15 minutes, and there is no other hidden slipper that could possibly be the source of that plastic.









http://www.am-autoparts.com/Volkswagen/Passat/TimingBelts/AM-749716439/624810.html

This image is not very good, it is from the top, and the 2 dark brown ramps are the slippers, one down and one up. I suspect the whole tensioner may have to be replaced.


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## vtraudt (Mar 1, 2010)

I have found broken off (brown) pieces of the chain tensioner 'guide'.
Also did some VAGcom check:

(block 91) Cam Bank 1: 34 degree
(block 92) Cam Bank 2: -3 degree
(block 93) phase position intake bank 1: 0, phase bank 2: 0


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## vtraudt (Mar 1, 2010)

So: 
Valve covers off on both banks.
Inspect 'chain glide' piece (visible, sits on top of the the tensioner).
Replace if damaged (use special tool to compress tensioner, lift up chain, slide guide out); NO need to remove or loosen cam shafts?

Then:
Check timing (timing belt) to determine if THAT is causing misfires on cyl 1-3.
If timing is OFF: what may have caused it to go off? 
a) sprocket slipped (on my 2.8T, the sprocket is NOT keyed, just cone/clamp/friction)
b) timing belt jumped

Belt is close to be replaced, therefore: change timing belt (water pump, etc).


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## vtraudt (Mar 1, 2010)

BTW: which side is bank one? Left (driver) or right (passenger)?
Which bank is cyl 1-3?


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## tryin2vw (Dec 30, 2006)

vtraudt said:


> BTW: which side is bank one? Left (driver) or right (passenger)?
> Which bank is cyl 1-3?


Bank 1 is the Passenger side/1--2--3 with 3 being closest to the firewall. Also CYL 3 is used for TDC. If the timing is off, it may also be the timing belt idler roller going bad and losing the bearings.


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## vtraudt (Mar 1, 2010)

How would a bad idler roller cause timing belt to slip or jump?


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## vtraudt (Mar 1, 2010)

Put crank on TDC mark.
Put cam lock bar on: timing off by one mm or so (= NOTHING). ==> timing belt is on the money.




Took valve covers off:

Chains seem tight.
I do NOT see damage to the cam tensioner guides
I found what looked like metal foil on 2 links of the pass side chain; remove with finger, seems to be some extra sealant.
I found a piece of alu foil in the driver side head. Had plastic foil as well. Looks like the sealing foil on oil cans. 

Link to photo album:

http://s853.photobucket.com/user/vtraudt/library/2002 Passat V6 ATQ

VAGcom blocks 90-93:


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## tryin2vw (Dec 30, 2006)

vtraudt said:


> How would a bad idler roller cause timing belt to slip or jump?


It would provide excessive slack in the timing belt for which the tensioner could not compensate. But you have found this to be the shoes on the CCT.


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## vtraudt (Mar 1, 2010)

Passenger side (bank 1) cam chain tensioner/adjuster was bad, bottom guide piece missing, chain cut into aluminum. Also 'rotated' (wear marks NOT in line with guide).

Replace. Correct timing (cam lock bar and TDC mark on crank perfect; VAGcom measuing blocks 90-93 show zero).

Fresh oil (German Castrol 0W-30) and filter (Mobil 1 M204).
New air filter.
Cleaned MAF sensor.

Also replace spark plugs (installed copper NGK BKR6E). Initial gap 32 (per lookup by parts store). Running a bit rough. Chilton says 63 (!). Googled, and found SEVERAL gaps, ranging from 34 to 63.

What is the CORRECT gap for the plain copper plugs?

Also noted noise for a few seconds during cold start.
Is the cam tensioner using hydraulic (or spring pressure), and oil is not getting to the tensioner quick enough? 

Is the ATQ engine prone to sludge, clogged oil pump pickup tube, clogged oil pump?

Want to make sure everything is up to snuff before putting car through 'stress test'.


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## tacurong (Jul 13, 2009)

*Passat v6 30 v spark plug gap*

The Bentley manual says .063 inch or 1.5 mm or so same as my 99 AHA /ATQ


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