mskar

Here is the water pump that was on the vehicle when I bought it:









The block looks like it had been bored about the depth of a credit card (91 barn find thread) but there is no play in this pump, and the impeller seems flush with the top of the shaft so I had my doubts that this pump was the one that did the damage. When I placed this pump back on with no gasket, it did seem to interfere slightly (without even tightening it down).

So... opinions... is it possible for a water pump to be so poorly manufactured that it damages the block even without any impeller migration?

The perceived interference I felt may have been the rust bubbling on the impeller but didn't really spend a ton of time on forensics opting instead to move on.

Any insight would be greatly appreciated, I'm really curious if there is any way of identifying the brand though. Thanks!

Speedtoys

If the pump fins have no damage, this pump didnt do it.

mskar

They don't look damaged to me but I'm not sure what I'm looking for?

Mikebte

Agree, you would see something on the pump if it caused the damage. More photos of the block if you have them.

Edit: You posted photos right as I replied

Looks like time has taken its tole on the pump. Needs a good cleaning for sure.

mskar

replaced. Not taking any chances. Found it odd that the rust was as bad as it was. I tested the the coolant and the PH and mix were spot on. Maybe depleted of all inhibitors after 12 years of sitting.

jcorenman

That was originally a Porsche pump with a late '89 casting date, which means it was almost certainly a rebuilt pump.
You've replaced it, don't look back-- plenty of adventures lie ahead.

worf928

The 'tell' is how much gap there is between the impeller and the casting. Should have very little gap: a mm or two. Can't tell from your picture. Shaft relationship to impeller doesn't tell you anything as the entire press-fit assembly can migrate in the casting.

At this point that '91 should be going onto its third or fourth or fifth pump. Could have been the first pump that chewed the block, the last, or any in between.

polecat702

Didn't Greg Brown, make an insert to repair a damaged block eaten up by the water pump impeller?

worf928

Yes. He did.

On the other hand, one or two mm (credit card thickness as per OP) of block-chewage won't cause a problem on a stock 928 with an otherwise operating cooling system.

mskar

Yeah there's a whole kit apparently, complete with an excellent Dwayne write-up. Since the boring was minute (less than a credit card thickness worn away, and perfectly smooth, I decided to go for it and install the new wp. Details in my "91 barn find" thread. Took a calculated risk, worst case, I have to go back in.