3b timing belt diamond washer or no diamond washer?

[twoqu]

Yes I thought about it. But for what purpose?

It's a good question!
One way to look at it is Audi thought it was important enough to introduce on later I5 variants such as 20V Turbo and TDI. I am assuming it was to prevent slipping between the crankshaft snout and the cam belt pulley which may be the cause of the fracturing of the keyway in the pulley. Fortunately this shortcoming has been overcome through the development of arguably better designed pulleys although that potential for slippage still exists without the grip afforded by a washer.
Febi have a fact sheet here:

http://www.febi.com/uploads/media/febi-e-90987-crankshaft-washer-diamond-coated-EN-GB1205_03.pdf

A more technical expanation:

http://www.esk.com/fileadmin/esk/medien/pdf/PL_ekagrip_automotive_e.pdf

[220bhp]

It would be interesting to know if the crank pulley keyway failure is more prevalent on the 3b, than on the aby,adu, and ann.

[Monkeymagic]

It won't be anymore as we are all running billet pulleys.
luckily the oe I removed was in tact. However I was able to remove and re fit my old belt without undoing the water pump! Slightly worrying

[sailaz]

For the record the TDI one is 34mmX19mmX0.13mm. Febi 31815 for X-reference.

should be the same measurement for ABY as well ? probably not ..
can't find measurements for 034105193 and any X-reference to other manufacturers ..
Febi 31815 is for 074105193 (or Corteco 80001156; SWAG 30931815)

[sailaz]

ok, here are measurements for 034105193 (ABY/ADU & some AAN depending on vibration damper) 34mmX18mmX3mm