Thread: 300Tdi serpentine misaligment

misalignment is often caused by the tensioner being worn on its shaft

since you are satisfied that that isn't the case, is there any other misalignment obvious ?

e.g. a pulley not seated fully on its mount , or cocked to one side ?

I've removed & checked the other pulleys.

I'll try a washer behind the tensioner to offset it. The only mislagnment is the interface of the tensioner and the water pump.

I heard today that someone had a "jumping" fan belt on a TD5 after assembling the front of the motor, and they replaced the tensioner,which only jumped some more. In the end the timing was out by a tooth.

I wouldn't have thought that a slight variation in timing would make a difference, but it did prompted to disassemble and double check it all again.

Check the alignment of the alternator, I had one crack through the body and mounts (I know not why) and it put the belt out of alignment, also wasn't real obvious with bolts on alt. tight but got worse as bolts were loosened off, Regards Frank.

aaarrrgh

With the new tensioner behaving worse than it's predecessors, I put a flat washer behind it to see if that would help it sit straight on the block - to no avail.

I went back to my original non-bouncy tensioner and went for the suggestion of placing a 5cent piece at the 9 o'clock position. I couldn't afford 5 cents, so a used a washer instead, but that has now brought the pulley into alignment.

Two days to do a 4 hour job - it's character building.

You shouldn't need a spacer anywhere to get the belt straight,methinks you need a good look at the whole job again. Pat

Originally Posted by PAT303

You shouldn't need a spacer anywhere to get the belt straight,methinks you need a good look at the whole job again. Pat

I know Pat, I've gone through the whole thing and the alignment issue is with the tensioner. It can't be with the water pump/block housing, as everything else lines up.

Others on the forum have had issues with squealing belts rectified by shimming the tensioner, which is where I got the washer hint from. Looking back, the long stud that the tensioner bolts up to was an eighth of a turn loose, which may have previously given it enough "flex" to mimic the shimmed position.

I suppose I can adjust the angle of the stud with a very slight bend. Maybe all these issues are related to a very slight bow in the stud, and when I tightened it, I changed the angle of flex. It didn't look bowed, but I didn't think to measure it's alignment.

I've seen Tdi-s with "bouncy" and smooth running tensioners, and I opted for the "smooth running" old one.

I've gone to a longer belt,a 1600 as mine had a bounce to it,the squeal can also be caused by the dust cover on the bearing put on back to front,it'll squeal like a pig.With the new tensioner is it mounting flush onto the bolt?. Pat

Hi pat, I did have an occasional sqeal before the change, but not any longer. The belt now runs true on all the pulleys and the tensioner.
It still has the washer at the 9 0'clock position acting as a shim, and given how common the misalignment issues on the tensioner are, and the less than perfectly flat face on the back of the tensioner, my suspicion is that the stud that it mounts to gets a very slight bend.

I'll probably be pressing some new fan bearings into 300Tdi timing covers this week, so if I remove it all again to fit a new timing cover, then I'll try adjusting the tensioner stud instead of using the shim.

The more I think about it, the less suspicious I am of anything other than the tensioner bolt / stud being the problem.