My heads are not shaved on the 87. All original.

 

Factory shaved block? With a 7mm install with a new Gates belt, then the engine is smaller than average, somewhere.

Hopefully, the compression is a touch higher in return.

 

Ken my engine is original, never opened up 87 S4 all records since new so I know that it has not been touched. After 20k on a gates belt and laso pump extension of my PKT black was 9mm. With the be pump and new belt it was down to 7mm (cold).

I have put on another 5k Km's. When I tear it down this winter I will measure it again. Before the factory unit goes back in.

 

I finally got a chance to tear into the WP today, here's what I found:
Belt tension cold -
https://rennlist.com/forums/images/attach/jpg.gif

Belt tension at operating temp -
https://rennlist.com/forums/images/attach/jpg.gif


PKT at 7.55mm -
https://rennlist.com/forums/attachme...1&d=1505259177

 

I'm not sure if it makes a difference but the belt tension may be a little high due to the Gate "Racing" belt.

 

Like I said, factory tolerances. Porsche was a small company. They used everything. (EG. '86.0 parts for the US only)

That engine got smaller before it hit the showroom floor. (Don't blame the ruler!)

It's OK. It's about how you use it, am-I-right?

 

Doesn't look like an issue to me. To take out the bit of slack that is developing because of sudden engine deceleration, the belt would need to be held much tighter. Much tighter. The slack is developing between moving parts and not where the tensioner is.

To make a reasonable evaluation, we'd need to see that test before and after a tensioner swap.

 

If we can keep one of these threads "above the belt"....

 

 

Yes, that's the car, I never measured the extension when I pulled the belt off but after re installation I did talked to another RLer that compared my pictures to what he had and said the tensioner (when re installed) wasn't fully extended. Might have been when I pulled the belt, don't know. If it was, it's a design flaw of the Audi tensioner bracket. The head gasket was changed by another shop so I don't know what they put on there either.

 

How about retrofitting a tensioner with a longer reach? This would fix the design flaw. Heck, stack them so when one stops extending, the other one takes over. Whatever it takes to fix the problem.

 

So now I'm only getting 9 months and less than 2k miles (if that) out of the fin water pumps!!!
Full disclosure, I replaced the WP last September as shown in this thread with a Geba unit as the Lasso WP I got from Worldpac was still under warranty and they no longer supply Lasso WP's. Believe it or not they claim 1% failure on the Lasso and 0.5% failure on the Geba. Take it all with a grain of salt. I figured what the hell the Lasso's are failing what do I have to loose. As I probably noted above I had already bought another new Gates Racing Belt and since there were 300 or so out there with no problems so I thought I'd just throw it on and change to a regular Gates belt over the winter. The Porken unit was within spec so I just chalked it up to really bad luck and nothing was gonna go wrong in a few months right? Wrong. Unfortunately I had some health issues that started last fall and I lost 6 months of wrenching time. Fast forward to spring and Hershey, and then a couple of short runs around town, a dyno run...
I'm going back to stock now. Good thing is I'm a GD pro at this and it will give me chance to get in there and really clean it up this time! GRRRR!
Oh the REALLY sucky part, I leave for Camp 928 tomorrow evening. Anyone want to lead the short fun run? Just wouldn't be right to do it in the Alfa:/

 

Hi Thom whats going on in the video?
You said you lost the new pump? whats happening ?

 

Stan,
Sorry, I thought I answered this early this morning. Basically I have the same problem I had with the other WP's that failed. If you listen you can hear the WP chaffing, it starts once it gets warmed up. Bearing is toast.

 

What was the dwell time between the 2k miles in the past 9 months? Do you drive it short distances often, or did you drive it quite a bit and let it sit for a few months? If this is a seal/bearing failure, this kind of drive cycle is important to know.

Once the engine is shut off when warm, there is pressure in the water system for a few hours. If the seal has even a small leak, or the shaft has a small defect, hot water(coolant) can seep in. If this happens a few times with long stretches of not running, the bearing race, and the ***** are subject to contamination. In a perfect world, 928s would get exercised regularly, and the seals would be perfect as well. The real world is different.

My catastrophic WP fail happened after the car had been sitting undriven for 7 months. I started driving it small trips, and then one trip it just gave up. I suspect invasive coolant got past the seal and into the bearing.