TDC timing mark

[vtraudt]

There is a TDC timing mark on the crank shaft pulley and a corresponding mark on the crank cover. The mark appears in a 'window' of the cover.
Does the length (maybe +/- 4 mm) of the crank pulley cover window indicated the 'tolerance' field for the timing?

Example below: TDC mark on left edge of cover 'window':

http://i1273.photobucket.com/albums/...psm9p9cy92.jpg

[okkim]

No, there is no the tolerance. I guess that the window is just to see the damper mark better. You should use the locking bolt to set it correct. The damper and plastic cover can be turban and you can have quite a big error if those are put in the opposite positions. But when you lock the crank with the bolt, and then tighten the damper to the plastic cover mark, you can use it to look the TDC. But you have to look always from the same position. Never ever trust it if you are not SURE that it is set correctly.

[vtraudt]

With respect to timing mark 'static' setup (cam lock bar and crank lock pin): this is no guarantee for accurate timing. The variable is the potentially different belt tension in each of the 3 divided (tension) sections of the timing belt (crank to cam1, cam1 to cam2, cam2 to crank). ONLY if cam sprockets (and any other roller/pulley aside from crank pulley)) can turn friction free (or close to) will the static setup be the same after tightening down the cams.
But loosening the cam sprockets bears the risk of slipping (only a friction setup, no keyway). Happened to me before (slipped a few degrees after torquing to spec (instead of the 'good and tight'), sprockets slipped a bit before 'biting' again on the shaft (puh, close). Since then, prefer to 'leave it alone if decent'.

Trying to define 'decent' for myself (i.e. when to crack the cam sprocket loose).

I forgot what the tolerance for 'good' setup is (obviously, there is always a tolerance from the (only theoretically possible 0.0 degree) ideal) in VAGcom (blocks 090-093).
Also in which direction the 'self correction' (over time, belt gets longer and timing gradually changes) is going: start slightly negative and belt elongation moves it to positive, or vice versa?

[zillarob]

0 +/ - 1deg is what you should see if doing it the right way.
Buddy never used crank pins and the ones I looked at were never more than +/-3ish.
Pretensioning the belt before you tighten the cams so the adjustment holds is a biggy.

As yours ages, it is going to go toward 0. That looks like quite a bit though and dont think it will ever get there.
Hard to say though because of what okkim said about the cover having some slop.

I love the tbelt setup on these cars, pretty much foolproof if you follow the directions. Cant get it dead nut on with keys.
If it were me, Id go back through it.

[vtraudt]

As yours ages, it is going to go toward 0. That looks like quite a bit though and dont think it will ever get there.
Hard to say though because of what okkim said about the cover having some slop.

Thanks.
So belt stretch (age) move from negative to zero (or low positive to more positive).
The respective VAGcom block numbers for the photo are:

090/1 and 090/2 show 0 to -1
091/4 adjustment bank 1: 0 to -1
092/4 adjustment bank 2: 0 to -1
093/3 and 093/4 "phase bank bank 1/2: -4/-8