Thread: 300Tdi throws timing belt - but why?

Too tight belt tension will cause premature failure.

Originally Posted by Taz

Hoping someone can shed some light here...

A few weeks ago my brother-in-law changed his timing belt in his D1. A brand new belt, sprocket and tensioner pully.

250km's later she went BANG! ...damage was 4 broken push-rods and 4 valves.

Upon removing the timing belt cover - the belt had shedded itself (see pics).

Any idea's why?

My brother-in-law offered the following description...

"Photos attached. You can see the flange on the crankshaft sprocket had been ripped off. Cause of valve/pushrod failure was a shredded timing belt, cause of belt failure is tracking issues. Not sure why the belt did not track properly.
The belt was installed to instructions as per difflock - however we did take the belt off after rotating it. At first my injection pump alignment pin was too large and was not locking in deep enough. We turned the engine over - but it would not fire because the injection pump was out of time. We removed the belt and reinstalled it again with the correctly sized locking pin. We didn't turn the engine over after this. Perhaps this was a mistake?
During first installation, then belt tension idlers where replaced and tensioned with a torque arm. After failure, the idler bolts seemed ok - they had not loosened. Tension was still on the belt after the failure.
Pulleys seem to be aligned with the naked eye. "

Looks like a good reason to change to gear drive, anyone done this and at what cost, Regardes Frank.

would be a good idea IF there was a viable option available...

Originally Posted by Tank

Looks like a good reason to change to gear drive, anyone done this and at what cost, Regardes Frank.

Google the Zeus gear drive kit, more failures and problems than a belt will give. Chain would be the best solution but that involves sealing the cover and comingup with a lubricating arrangement and then draining excess oil back to sump.

What year D1 ?

Didn't pre '97 TDIs have a timing belt mis-alignment problem ? Even so, sounds early for this to manifest.

I thought there was a mod for this. Not sure if that engine has it but the crank pulley should have a lip either side of the belt to stop it coming off. The mod may even have it on an idler pulley to, can't remember. Ring Davis Perf Landys.

Yes - mod kit was fitted. BIL says the damaged belt removed the flange on the crank sprocket.

back in 1998 a problem of thes nature arose in new vehicles a recall was put in place and the vehicles were modified with these bits LHH100600/ DRIVE GEAR,LHV100150 IDLER ,LHP100860 TENSIONER. Brit part /bermach do these kits and to the best of my knowledge are the only ones that should be fitted not the earlier type up here on top the kit will cost 300 e . O! ya mind the tension too much breaks em eveytime