what a totally MORONIC design. press fit 101 here. they needed to use much coarser knurls and the the thing would be bullet, until the cheapo bearing design failed. :roflamo:
this should be a total embarasement to the design team that was involved with the pump. just plain stupid! hydralic forces, plastic material impeller, shallow knurles, press fit?? sure, like its going to hold! Idiots! at least the metal one has a fighting chance!

 

nah, thats tar sound deadening material.

 

They use the same type of plastic impellers on many other Euro cars, BMW and VW come to mind.

 

Agreed. Obviously why Porsche chose to change the design, years ago.

I've not seen many of the plastic impellers that have failed...certainly less than half a dozen...so I don't consider this to be a significant "weak" point.

 

The absolute only attraction of the Laso pump was the metal impeller...and now they changed that. I'm not sure where you might find a metal impeller on a pump...unless you bought a rebuilt unit.

 

I'm not positive when they made that change....that would be interesting to figure out.

The seal, in this pump, appears to be the same one as I've seen in all the "factory" pumps that I've taken apart....that is why I thought this pump to be factory. Perhaps we could get the owner to tell us what the "date" stamp is.

 

+2 I will take a gradual overheating condition over block damage any day of the year...

 

My 89's original WP, not changed before I got the car in 99, had a metal impeller. The 1990 Service Info Tech book states: "Material of the water pump impeller was changed from gray cast iron to plastic for reduction in weight." But, like a lot of such changes, it could have been done mid-model year 89 sometime. My car is fairly early 89 (barely late enough to get the 2R heads)

Hey, Imre, you said: "I pulled the thermostat on the side of the road but it don't made a difference." You know, the 928 T-stat does the reverse of more common designs (it closes off a radiator bypass passage rather than opens up a passage to or from the radiator) and if you remove it, coolant flow to the radiator only gets worse.

And don't feel any need to explain the green coolant. That's what Porsche used and I continued to use, although recently I switched to universal yellow. I never was sold on Dex-Cool for our motors.

 

Nope!

Here the thread: https://rennlist.com/forums/928-foru...-gts-deal.html

 

Nice car Jim, great decision to buy...........if you ever think of selling the GT you know my number

On topic, the WP out of my 88 is smooth casting with cast impeller and its tight. It was replaced as I was in there for the timing belt etc.........in retrospect it could have stayed in placed but I would have had doubt. Now there a new Laso in there I do feel better but will install the new and improved WP at the very next opportunity

 

I'll clean up the old pump this evening and see what numbers are there.

Bill, yup figured out after we towed the car home that there has to be a thermostat for the system to work. That why I put a good used one to drive it home from my father's machine shop.

I've been thinking about how this copuld have happened and have a theory. The bearins are clearly shot as there ia at least a couple mm of play at the pulley. What I think happened that since it was a plastic impeller, when the shaft play became big enough, the impeller got pushed against the back of the pump. This force pushed the impeller off the shaft and into the block. If I put the impeller back in the shaft, it still catches the shaft but as soon as I pull it a little forward, it starts freewheeling. So since the impeller is platic, it detached from the shaft a lot easier than a cast iron one. Because of this, it couldn't dig into the back of the pump or the block, locking up the pulley and melting the timing belt.

If this is all true, then this setup is as good as that new WP that has the rubber clutch/coupler pulley .

 

The pulley has a 928 number too.

 

Except that the impeller is pinned...

 

Ah hah. Ok then, so it was either a really old factory-original or one of the POs sprang for a new pump from Porsche during the last t-belt/pump dance.

Edit: No. wait. I'm confused. Long day... nevermind. Nothin' to see here. Move along...

Good to know.

 

Yes but it's plastic so no damage to the block. Unless the bearing siezes (I don't know how common that is), the outcome is the same. Car overheats and you stop.



The splines/cross hatching on the shaft is very, very shallow. If they went with something like the windshield wiper pivots, it would have a stronger grab.