Timing belt tensioner failure
 

Started my car yesterday after it had been parked for a few hours on a steep slope, straight away it sounded terrible so it was quickly switched off, its a high mileage engine but had belts, tensioner and pump replaced 3 months ago so I was at a loss as to what could have happened, thought maybe low oil and the angle it was sitting had starved it but when I rolled it onto the level the oil was sitting perfectly at the max mark on the dip stick. Towed it to the garage that did the work, apparently the tensioner has failed, the cams are in time but it is 3 teeth out at the crank.

The garage suggested as it was parked on a slope the hydraulic tensioner wouldn't have had enough pressure but this sounds like nonsense to me, they are going to retime it tomorrow however I can't say I'm confident that the valves will have escaped damage, it still runs but sounds terrible...

940 tdi auto 1995
 

hi what engine is it ? hope its not the diesel !!!!!!!

3.0 24v

whoever told you that is talking out the hole in their arse!

Either poor parts or poor fitment, who supplied the parts?

Garage supplied parts, they swapped the engine out of a car I've owned for 6 years into current one which I bought with a duff engine back in Sept, water pump went 3 weeks later so told them to do the belts and tensioners at the same time, it has 280k on it but the head was rebuilt 3 years ago so was running perfectly

The tensioner is the same as the 850 and early x70, they don't fail.


To me it sounds like a fitting issue. I would ask them to show you exactly what went wrong, anything is possible

Does the belt on this engine need re-tensioning after a "running in" mileage? If so. Was that done?

Hej monty,

if the tensioner was tightend,without camshaft weels giving a play, this is the reason. In this case it is not made sure, that the belt runs proper in the cogs.
This is a special thing with the hydraulic tensioner.

Hej Hej Gernot :)

Sorry, I am not sure what you mean...?

Update from the garage today, they retimed the engine and turned it by hand to check for interference then started it, it ran for 2 secs and cut out, it now has no compression so assuming the valves weren't bent before its safe to assume they are now. They haven't been able to shed any light in why it jumped 3 teeth on the belt in the first place or what happened today, good thing Ive got a spare head, looks like im going to need it...

Looks like the key on the crank sheared off so the bottom pulley is spinning, hoping it's on the pulley and not the crank as I've got a spare one, otherwise it'll be time for another engine.