StratfordShark

I had a new TB and water pump installed a few months ago (tensioner boot was also changed). I was going to re-tension it myself at 1500 miles but own up to going over that. The wake-up call came when I got a tension warning light at 2200 miles after a kickdown.

Was worried then about getting warning at 2200 miles, when I understand almost all stretch on new belt occurs much earlier.

Using Kempf tool showed belt was loose (a few mm past left edge of window) so I tightened till it was at right hand edge and confirmed this after another 2 revolutions.

Have done just a few hundred miles since and checked the tension today. It was back at left edge of window!

The other symptom relates to water pump. I've been getting a few drops of coolant dripping off front of sump. I have checked hoses for tightness and suspect the leak is from the new water pump.

Obviously I am going to talk to the guy who did the TB job and take the car back to him for a check-up. Meantime what are the likely suspects? Could it be a problem with the tensioner itself? Could whatever is causing the possible water pump leak also cause loss of belt tension?

Thanks for your advice.

JHowell37

If the water pump itself is leaking, then it's certainly possible that it could be causing your tension issues. On mine, I waited until the light came on before I checked it the first time. That's not a big deal.

Unfortunately, the problem with the coolant leaking could be from a number of sources such as:
1. Defective water pump (which isn't uncommon, why something so simple is so hard to get right, amazes me.)
2. Loose or not properly sealed bolt on water pump.
3. I think the S4 has a bolt on the tensioner that goes into the water jacket they may be loose or not properly sealed, but someone else can clarify that.
4. Bolts for the thermostat cover are loose/gasket leaking. I had a coolant leak on mine right after I did the timing belt and that turned out to be the culprit.

What is unfortunate is that solving this mystery will require some digging, and maybe even require a re-do. I guess it's better then having to have new heads put on.

worf928

All that was changed was the belt, water pump and boot? No idler rollers? No pivot bolt bushings? Same pivot bolt? No new cam sprockets? Or oil pump sprocket?

If your car was older than early-87 I would opine that the problem is a sagging pivot bolt. This is the bolt that screws into the water pump and around which the belt's idler and tension roller carrier rotates. However, you car should have a pivot bolt brace (pictured) - visible without any wrenching - that prevents sag of the bolt. If the brace was left off.... or if the bushings for the bolt-to-carrier interface were not renewed and the 'new' pump was bad...

StratfordShark

Thanks - that's extremely helpful.

I think I can rule out T-stat cover as I took this off when I replaced coolant bridge gaskets (after t-belt change but a few months before leak started). I was careful replacing the gasket at the time and snugged down the bolts OK (famous last words!). No sign of any leak in that area if I rev the engine using throttle bracket.

StratfordShark

Just popped out to check and at least the pivot bolt brace is present and correct (what happened to the engine lifting shackle in the photo btw?).

As for whether other parts you mentioned were replaced I'm in the dark apart from cam sprockets which I know are the originals. My fault as I meant to buy new ones before the TB job as I thought they looked worn.

Thanks for valuable pointers.

worf928

Are you sure that the engine was at TDC for Cylinder #1 when you checked and set the tension? If you set the tension at TDC for #6, the actual tension will be at the bottom of the Kempf window. TDC for #1 will occur when the balancer reads zero and the notches in the cam sprockets are 'on top' and aligned with the notches in the backing plate. TDC for #6 will be balancer at zero with notches 180 degrees from the top.

StratfordShark

Hi Dave,

I definitely had notches in sprockets at the top when I had the balancer at 0 tdc on each occasion when I set/measured tension.

worf928

OK. Just checking.

Too bad though; A change to the measurement procedure would have been an easy fix.

Bill Ball

For informational purposes, what was the source of the water pump? New/rebuilt? Laso or Porsche casting? For the last item, you can determine that with the pump still on the car, as shown here:
https://rennlist.com/forums/showpost...5&postcount=25

StratfordShark

That's a very interesting point to identify the pumps Bill.

I just dashed out and played with small flashlight and my flexible inspection mirror. That bolt is recessed in same shape as the thread you referenced, so pump must be a Laso. I didn't ask if it was new or rebuilt at the time but will check when I talk to the guy who installed it.

Mrmerlin

you can tell if you used a new or used pump by the price all other things being equal... new should be about 350.00 rebuilt about 110.00 USD