good point and thats how most of them fail too! ive only had the plastic impeller from porsche , fail.. ever since then, ive used the metal impellers. but, they fail as Hacker described. so, i guess we need the special custom pumps or take our chances with the after market OEM stuff.

 

Like the porsche factory OE pump that had the impeller spin off the shaft?

 

We have a custom special pump from OBehave2.0:
http://perfexmfg.com/EGDS_water_pump.php

The pumps Roger sells all have plastic impellers which eliminate any worry of block damage. Sure the impeller could still fail causing an overheat issue, that is why we have a coolant temp gauge.

 

There is no solution to 928 water pump woes that is without some flaw. It could still leak or seize too. I had the ability to protect the block so I did. If it walks forward hopefully I'll hear it or see it damaging the front cover.
If I had modified it to solve all the possibilities somebody would still find something to criticize.

The one on there now is a Laso w/plastic impeller. Leaking after 20K. There are bad features about all of the possible choices.

 

Other than the possible block damage, every other issue you may run into with a 928 water pump can happen to any water pump for any car.
If our engine design didn't allow the impeller to come into contact with the block, we wouldn't be having these discussions and most would be happy buying a $100 rebuild (like the 944 guys do).

Nobody is criticizing your work, just pointing out if you are trying to eliminate block damage, the impeller moving is only half the problem (maybe even less) compared to the bearing failing allowing the shaft to move. You won't have any more warning this is happening than if the impeller moved prior to the pinning.

Frankly this discussion is an overblown mess, buy the plastic impeller and be done with it or go with the Guardian system.
Yes I have a stash of rebuilds (with metal impellers) I plan to use, but the person that rebuilt them retired years ago so that option has been eliminated for me, unless I convince Turbo Todd to rebuild a couple, but frankly as he put it, the effort isn't worth it compared to buying a new one.

 

Leaking is the only problem that will never be fixed as the mechanical seals used in water pumps need to "leak" or seep, to some extent, to lubricate themselves. That is why the weep hole is in the pump housing to allow any leakage or in this case seepage to escape the bore to protect the bearing. The key is to use quality seals and install them correctly. There is a special way these seals have to be installed and if not done correctly the will break, or leak slowly or burn up and leak sooner.
Out of all the pump options out there,IMHO, my version is the best at combating all of the prior failure points witnessed in the past. Even with a solid coupler it is a better way of driving the water pump as well as idling the timing belt system.
Not trying to sell here,I have no issue with however anyone wants to fix their car, and if I can help I will.

 

Can Ed use your cores?

Or more correctly: would Ed use your cores?

 

I've seen your product & think it's a big step forward. I'm just not in a financial position right now to be able to afford it.

Regards, Hammer

 

I should play the lottery. After the leak appeared I stopped driving the car immediately & that was the smartest thing I could've done. Got the water pump off today & you could barely turn it by hand! It was about to seize! Looking through the seep hole I can see pieces of seal/bearing material in disarray. Thank God I didn't drive it or my GT motor would be scrap! Other than the leak I had no warning. It didn't make any noise. Scary to think what could have happened!

 

ok, we forgot the 3rd mode of failure!

1. impeller comes off shaft (damage block if not caught in time, or just overheat with plastic impeller
2. entire impeller and bearing comes off the housing and migrates toward engine
3. bearing seizes and burns up belt and bend valves.

maybe the pump should just be a maintenance replace item, oh yeah, the new ones are sometimes worse than the old ones you might leave in there.! UGGG

 

This has to be the weakest link in this engine. And the most dangerous as far as damage potential & expense.

 

Why would your GT engine be scrap if the pump stopped spinning? Some bent valves and thst's propapby it. Hardly a scrap.

 

I'm talking about major expense & repair. Bent valves ain't pocket change.

 

i was just thinking of the work, just to change the cams out.. let alone more work to pull the heads to get the bent valves out! It's not bad work.. kind of fun, but its a LOT of work!
basically, just pull the engine, right?

 

Can somebody confirm that the metal impeller coming off the shaft is a real issue that would benefit from pinning? I've seen plastic impellers do that with some regularity until Lasso redesigned the shaft to include a bushing. I know the metal impellers have reamed a number of block faces, but my recollection is that was due to migration of the entire shaft and impeller assembly due to bearing failure. I've had a rebuilt metal impeller water pump on my car for 120K miles or so with no issues. I used to change water pumps with each timing belt job, as became SOP around here, although never prescribed by Porsche. It bothered me that the old pump still seemed to be in near new condition. So, with the last few belts, I just evaluated the pump condition and finding it with no significant play, noise or evidence of loss of grease (no freewheeling) or leaks, just let it be (knock on cast iron).