Can't get alternator belt tight enough

[bvolks73]

Finally got it back together and properly adjusted today. Amazing how easy it is when they finally give you the right belts. At least the weather was nice while we were putting it back together. :roll:

[Quantum TD]

Today, I just did this job on a 1991 Jetta ECOdiesel (TD).

A couple of impressions:

1) Take the intake box off: makes life a lot easier.

2) The book calls for a 10X 695 mm belt. If you use that belt, it will have very little in the way of adjustment down the road. I managed to squeak a 10 x 675 on there with some clever movement of the idler pulley. A 10 x 685 might be the perfect compromise: easy to get on, and plenty of room for adjustment.

3) The car I worked on belonged to a customer. I sold her the car a year and a half ago. Before I sold it, I put on all new belts. She's come in from time-to-time for minor repairs. I've noticed that the alt belt was always loose, even after I had adjusted it during each prior visit. In the end, the belt lasted only about 12,000 miles before it snapped off completely. Inspection of the ***ty stamped-pulley showed SERIOUS pitting of the belt surface. As I noted earlier, this is what caused premature belt wear. Luckily, I had a spare alterntator with a good pulley on it, so I swapped it. We'll see how it goes.

It is my contention that if anyone out there is eating alternator belts on a MK2 car, there's a 99.99% chance your pulley is pitted and eating the belt.
If you need a NEW pulley, only the dealer has it (and, I called my local dealership and they claimed that they were still available).

Here's the PN for a new pulley: 035-903-119

Cost is about $40-60.

To the OP, hope yours works out.

[bvolks73]

The alternator belt is working out ok but the AC belts are not. We've put 2 on it within a couple hundred kms and are having trouble again. The first one broke within 50 kms for no apparent reason. We looked everything over and didn't see any problems so we put another one on and it was fine for a few days but today it started squealing and just can't be tightened enough. It doesn't make any sense because when we put it on it was so tight that we had to force it over the AC pulley and now it's so loose that it's flopping even when the tensioner is maxed out. I don't understand why they're wearing so quickly. The pulleys look fine to me and don't sem to be rusty or pitted. This is getting pretty frustrating considering it's been around -30C for the last few days.

[jtanguay]

The alternator belt is working out ok but the AC belts are not. We've put 2 on it within a couple hundred kms and are having trouble again. The first one broke within 50 kms for no apparent reason. We looked everything over and didn't see any problems so we put another one on and it was fine for a few days but today it started squealing and just can't be tightened enough. It doesn't make any sense because when we put it on it was so tight that we had to force it over the AC pulley and now it's so loose that it's flopping even when the tensioner is maxed out. I don't understand why they're wearing so quickly. The pulleys look fine to me and don't sem to be rusty or pitted. This is getting pretty frustrating considering it's been around -30C for the last few days.

i had the same problem.. the main large belt (goes from crank, wp, a/c) was very tight... needed to 'jump' it on.  i went to Canadian Tire and bought one of their cheapie belts.  worked like a charm!!! try that.

[bvolks73]

I think I have it figured out. I spoke to my mechanic last night and he said the belt will wear out quickly if the double pulley on the water pump is stuck (which it is) and the power steering is hooked up. That's probably why the power steering belt was disconnected when he bought the car. He recommended trying it for a while with no power steering belt and if it doesn't ruin the AC belt to get rid of the double pulley on the water pump and run a shorter belt to the power steering.

[bvolks73]

Ok, now I'm stumped. Does anyone have any pics/ diagrams of the belt setup on a 1990 Jetta TD with AC  and PS ?  My mechanic claims it should have a freewheeling pulley on the water pump that acts like an idler for the AC belt but I see no mention of it anywhere else. He claims that if there is no freewheeling pulley then the PS belt should only run from the crank pulley to the PS pump, not around the water pump too. The way this one was setup when we got it had the water pump driven by both the AC and PS belts, which doesn't seem right to me. HELP!

[Quantum TD]

Your mechanic is right. At least on the American 1990 TD (or ECOdiesel) the water pump had a free-clutched water pump pulley. It is similar to the design used on the 1985-1992 gas cars, but is smaller in diameter.

Here's the PN for the one used on the 1991-1992 ECOdiesel (should be the same for yours):

068 121 028


For reference, the gasser one looks similar and is PN: 027 121 028

If you need an image, go to www.vagcat.com. You'll need to sign up for an account before you can view images.

Having said that, it sounds like the PO took off the PS belt because of the stuck free-clutch pulley. It's a dealer only item, and is not cheap ($170 at 1stvwparts.com!)


You might be able to free yours up. They simply delaminate n(i.e. pry it apart) and you might be able to clean up the internals. But IIRC, there is a plastic liner in there that can tear. If that happens, then you need to replace the whole unit.

Good luck.

[bvolks73]

Unfortunately the free clutched pulley is gone. It now has 2 separate pulleys on the water pump. I even tried the gasser one I have with a longer belt but it wouldn't clear the crank pulley. I know now why the PO was running it with the power steering belt off.