And I direct my purchasers to change them every 3 years, despite mileage.

I am currently working on something……. More than one thing.

Jake, Greg Brown on the 928 forum (been building and modifying 928 for decades) built a system to repair scored 928 blocks that had impellers dig into them. Its a very clever system where there is a custom mill and then different size spacers that brings back the block to factory clearance. It's a portable system run off a hand drill. Very simple to use and is most importantly accurate. Thought might interest you. Could be easily tranfered over to M96 engines.

The issue is consistency between crankcases in this region, which is all over the place.

But the key is a wear surface that's installed when the water pump is.. That wear surface is disposable should the impeller take it out... This isn't something worth patenting so I may as well spill the beans.. It'll just get copied faster now, that's all.

Anybody try pierburg pump ? Oem supplier

We've installed a couple hundred of them over time. I've had one of them leak within 3 months, buts thats all. One more lost a bearing within 6 months.

Quality goes up and down between all the different choices with each batch. Whats good today isn't in 6 months. The only thing that stays the same is that everything constantly changes.

makes sense, and making the impeller a bit smaller diameter won't impart a significant change to coolant flow rate. Must mean a new pump head casting, or machining a groove in an old casting?

2003 Carrera 4S Speed Yellow / 1955 356 Continental 1500 Rust Red

Isn't there an electric water pump solution and just delete the troublesome water pump from the equation?

The particular pump will not move enough volume. I have been working with John Benson, Director of Davies Craig, the company that makes the EWP 115. The 115 has proven to only be adequate to act as a post cooling pump after the engine is shut down, or to boost volume when used in conjunction with the stock pump.

We are developing the EWP150 version of the pump now, to see if it is adequate as a sole unit, or not.

Cool. Watch this space then.

I understand the joke, but....

Hot oil with a modern detergent package is pretty good at washing away grease. Hot water and antifreeze not so good.

A water pump bearing will start to leak coolant early on...and will be easily seen by a careful owner. The IMS bearing is hidden away inside the engine and won't exhibit easily observed signs of incipient failure.

Interesting thread. I will probably be changing out my water pump and serpentine here soon. Figure I might as well before the turbo goes on.

May be I'm missing a point here but do the plastic impellers ever fail with out a bearing failure? If they don't the only advantage of a metal impeller is that it may not fracture and send small pieces into your water ways. However it will chew up the mating face on your block and require a engine rebuild to ensure the correct coolant flow.

It's not the mating surface that gets chewed up by the impeller and I'm not sure how an engine rebuild will fix this. It would have to be repair for the waterpump cavity.

My thinking / understanding was it was the clearance face on the engine block (LH) which gets chewed as the impeller is able to move around. The chewed up face would need to be at least cleaned (removing material) or replaced since the surface is part of the block this would require a new half block or a shimmed face for the pump either way it would probably require the breaking down of the engine and hence a rebuild.

Guys on the 928 board already figured out how to fix a dug in water pumped block. There is no reason the method couldn't be duplicated on our engines too. After all the 928 is an all aluminium block too. Their technique doesn't require anything more than removal of the water pump.