Brantley

In the middle of replacing my water pump / belts / engine reseal.

I bought a cheap remanufactured water pump on Ebay - HERE.

Attempted to install it today, but once I torque down the nuts / bolts to 6 ft-lb, the impeller touches the block / doesn't spin.

Took it off and the impeller is a fair bit larger than the one I am replacing. Picture here -



I installed the old one just to make sure I wasn't doing something stupid and that installs no problem.

It doesn't appear that the impeller sticks any further out the back of the pump than the reman one.

So, I think I have cheaped out and it is coming back to haunt me. I will probably buy a new one from Pelican or Paragon.

Did I miss anything? Any recommendations for a new one?

Thanks,
Mike

PorscheDoc

Looks like the 3.0L pump.

blown 944

You can easily grind off the little protrusion on the block to add clearance. Very easy to do.

Yes it's probably a 3.0 pump

michaelmount123

It's a 3L pump for sure. 2.5's had the smaller impeller, 3.0's larger. Don't hack it up to fit. Your block is machined for the smaller impeller.

Pauerman

You've got a better pump there - grind away the small amount necessary and you're golden.

blown 944

Curious why you wouldn't use the larger impeller? I've clearanced my blocks and have had no issues...

It seems to run cooler at idle. Otherwise, no difference.

I had heard that this had been done for years prior to me doing it.

Curious of you thoughts.

Brantley

I think I will get to grinding. Looking at the tab on the block and how much needs to be taken away doesn't look like very much! Better than buying another water pump...

Thank you all!

Chris White

Make sure that you have the 2.5 pulley on the front of the pump and not the 3.0. the 3.0s have a much wider belt.

Pauerman

The 16V belt is wider but the pulley for either the 2.5 or 3.0 pump is the same. I just measured both, so can confirm positively.

87944turbo

For future reference Zim's has been a trusted source for rebuilt water pumps for many years. Offered with a 2 year warranty for not much more than the eBay pump (http://www.allzim.com/store/cart.php..._detail&p=1041). Looks like they've gone up a bit, when I did mine they were $84.

Brantley

Chris... good point, I'll look at this a bit closer before i do any grinding but didn't notice any different by eying them both. And, thanks Pauerman for the confirmation on your side.

Hmmm... solid price for sure and would consider using them in the future.

Thanks,
Mike

michaelmount123

I'm always impressed that people will try to make something work, even though it's not quite right from an engineering perspective, and have successful results. I would never have suggested using an offset ground Porsche crankshaft in a high power application without re-hardening it for both strength and wear resistance. I'd also never recommend running a turbo piston that's well down in the bore at TDC just to lower compression. BUT…. some of you great hot rodders have made these and other things work. My hat's off to you!

Regarding my H20 pump comment - more of my (dinosaur) opinion: Porsche revised the pump when the 3.0 came out. At the same time they revised the cooling passages in the block; including both the area adjacent to the water pump, and the depth of the water jackets. They paid an engineer to change the design, and invested a fair number of Deutschmarks in the revised casting. If Porsche felt the 3L water pump was simply "better" as some have suggested, why haven't they superseded the old pump? The large impeller pump is designed for the 3L block, and the small impeller pump was designed for the 2.5 block. No one can dispute this. I'm not sure you'll ever convince me one pump is 'better' than the other, or that one is 'fine' on either block. The engineer in me just won't accept it. Now, I won't ever dispute that it 'might' work, or that 'maybe' it will be just fine. I'm hoping you get my drift.

Cheers to all.
MM

Chris White

That's it, now I have to rename my sons Tyrannosaurs Rex "Michael".....

blown 944

Thanks for the response. I get what you're saying. Obviously I am pretty adventurous when it comes to trying things that are out of the box. I am not really tied to anything "Porsche" developed I guess. Tbh I will more than likely be running an electric BMW water pump in the end. For this though, I looked at the shape of the scroll and didn't see a variance other than the tip coming down to mate with the smaller impeller. Then I tried it and it worked ok. I rationed that the 3.0 was specd to a higher redline as well, so rpms shouldn't matter.

The reality is that on something as small as this it just needs to work.

As for running the pistons down in the hole, lol. Learned that this works fine decades ago with a destroked blown alky sbc. That also worked very well.

As for the offset grind. You confirmed that it works great with henks build. I just took it on a little different path and cheaply.

refresh951

I would call it "educated risk taking all in the name of fun" We have to do something different, when you go to sell a car nobody will give more than about $8K.