worf928

My $0.928:

I've bought three Porsche rebuilds in the last year and all had the plastic impeller.

For my own cars I will use the plastic impeller as I've seen the damage done to a block by a wobbling metal impeller.

For other people's cars I will go with either plastic or metal depending upon the owner. If I know that the owner pays attention to the temperature gauge and is otherwise **** about how the car runs, I'll recommend plastic. If the owner is kind of oblivious I'll recommend a metal impeller since the failure mode is usually more obvious - leaking - than that of the plastic - higher temps.

heinrich

What he said

Dan87951

Just got home and the water pump I took off appears to be a Porsche rebuilt unit. It has a sticker on the top that has the Porsche logo on it and said Porsche and made in Canada. The sticker is yellow and chrome in color. The part# also ends in a R. The pully is locked tight and there is no gap between the impeller and the housing its almost like it tried to pull it self away from the block.

Prionace Glauca

Here's some interesting data on water pump seals and bearings taken from the *** catalog.

John Veninger

My NEW Por$che water pump came with a plastic impeller.

ROG100

Ed,
Thanks for the *** doc - very interesting reading.

I would trust Dave & John over my memory and it looks like the current Porsche units are plastic.
Last one I had was metal - maybe order another one 8>)

SteveG

I didn't know they were obs. The reasoning WAS that if the shaft or bearing fails, it usu goes aft and plastic won't eat into the block. I know that is what I rec'd in a re-built piece 5 years ago.

Jim bailey - 928 International

The plastic impellor is the newer version and far more common especially for the S-4 > cars . We source directly from the rebuilder no middle men and since nearly 20 years ago Mark got them started doing 928 pumps and they later began to rebuild for Porsche and others they have always remembered who got them into the 928 business.

The_Remora

that *** document (snicker snicker) was interesting, the last page really outlines the catastrophic effects caused by eccentric loading due to incorrect belt tension.

I wonder if there is a correlation with people who are inclined to buy cheapest possible parts, (ie ebay, Chinese knock offs, etc) being more prone to doing hack install jobs, while others who spend more on quality OEM parts being more **** with the installation procedure and belt tensioning. There probably is a disparity in manufacturing quality as well, but it sounds like the element of human error plays a big role in the failure rate. just a thought.

ROG100

So if you feel you need plastic impellers buy the rebuild from Jim or get the rebuilt factory from Porsche via your fav 928 supplier.