996 Water Pump from Bosch
07-27-2014, 09:45 PM
#3
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Hope it has a non metallic impeller. It's really hard to beat the OE Porsche pump.
07-28-2014, 10:32 AM
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07-28-2014, 10:47 AM
#7
Burning Brakes
http://www.bavarianrocketscience.com...ng-water-pumps
Definitely another point of view ... I was in the "plastic impeller" camp, but now I'm not so sure.
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07-28-2014, 07:28 PM
#8
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When your pump fails, and they all do at some point, you don't want metal on metal shearing your case.
07-28-2014, 09:13 PM
#9
Burning Brakes
FWIW, one of our local indy shops -- well-respected and very experienced -- prefers to install pumps with metal impellers. This blog post lays out their rationale:
http://www.bavarianrocketscience.com...ng-water-pumps
Definitely another point of view ... I was in the "plastic impeller" camp, but now I'm not so sure.
http://www.bavarianrocketscience.com...ng-water-pumps
Definitely another point of view ... I was in the "plastic impeller" camp, but now I'm not so sure.
I'm not sure that I buy it though. If I recall correctly, water pumps should be replaced based on mileage and time in service (4 years?) so if I'm going to replace it periodically why wouldn't I use the factory spec item? Also I'm not sure what to listen for to know if the metal impeller pump is going bad and how long I have before it starts engine gouging.
07-29-2014, 12:03 AM
#12
Former Vendor
About the same chances as having a bearing failure and the cooling system being filled with chunks of metal as the metal impeller becomes a "milling machine".
Remember, its a bearing failure that makes the plastic impellers break off and fill the cooling system. Until someone steps up and makes a tandem bearing pump (like we already designed) the units simply won't be robust enough, no matter what. The metal impeller is also heavier and that increases load on the bearing.
When our tandem bearing pump was available no one would spend the money for it, so they were all used on our engines only.
Remember, its a bearing failure that makes the plastic impellers break off and fill the cooling system. Until someone steps up and makes a tandem bearing pump (like we already designed) the units simply won't be robust enough, no matter what. The metal impeller is also heavier and that increases load on the bearing.
When our tandem bearing pump was available no one would spend the money for it, so they were all used on our engines only.
07-29-2014, 12:40 AM
#13
Burning Brakes
It is certainly a point of view. Do you know if they recommend metal impellers for the 996? The blog post does say "some designs require plastic, as metal could do damage as well. In some engines the water pump is located very close to the engine block and if a metal impeller was to fail and score the block from rubbing against it, major damage can occur." It seems that they're saying that (1) replace your pump every 30-50k miles, (2) you can hear metal impeller pumps going bad, (3) get your car regularly maintained. I'm not sure that I buy it though. If I recall correctly, water pumps should be replaced based on mileage and time in service (4 years?) so if I'm going to replace it periodically why wouldn't I use the factory spec item? Also I'm not sure what to listen for to know if the metal impeller pump is going bad and how long I have before it starts engine gouging.
