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996 water pump failure with pics

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Old 09-23-2015, 06:09 PM
  #31  
Schnell Gelb
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I recently completely dismantled and rebuilt my M96. The P.O. had replaced the WP+thermostat. Dismantling showed some superficial scoring of the WP housing .The big surprise was finding bits of his old plastic impeller scattered throughout the engine coolant system.There was quite and accumulation in the oil/coolant heat exchanger. Had the c/s bearing not failed, the cylinder head would have overheated anyway.
So how do you know if you found all the broken impeller pieces ? You try to reconstruct the damaged impeller with the bits you recover. Yup, it is nonsense to think you will find them all.
Metal impeller has it's own issues. So precautionary replacement seems the only intelligent solution ?
Old 09-23-2015, 06:50 PM
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rockhouse66
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So it is consensus that you replace with an OEM design with the composite impeller and figure on routine replacement or a different design with brass or steel (or whatever) impeller? What are the issues with a metal impeller?
Old 09-23-2015, 06:53 PM
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KrazyK
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I replaced mine as PM when I dropped the engine for other stuff. Mileage was @56,000 and pump looked fine but better safe than sorry. I would drop the engine at no more than 60,000 miles and do all the usual PM stuff.
Old 09-23-2015, 06:56 PM
  #34  
jmj951
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Originally Posted by rockhouse66
So it is consensus that you replace with an OEM design with the composite impeller and figure on routine replacement or a different design with brass or steel (or whatever) impeller? What are the issues with a metal impeller?
If a water pump with a metal impeller fails the way mine did, the block will be damaged and require repair.

The bearings on my water pump became so loose that the shaft was running really crooked. That broke up the plastic/composite impeller that I had. With a metal impeller, it would dig into the block and damage the face. This is a big problem because there must be a close tolerance between the impeller and the face of the block in order for the impeller to work properly (to have the proper flow of coolant).
Old 09-23-2015, 07:08 PM
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JayG
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Originally Posted by KrazyK
I replaced mine as PM when I dropped the engine for other stuff. Mileage was @56,000 and pump looked fine but better safe than sorry. I would drop the engine at no more than 60,000 miles and do all the usual PM stuff.
whats your mileage now, 56,100?
Old 09-23-2015, 07:17 PM
  #36  
bradbeck
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I would expect the longevity of the impeller is determined by how good the coolant is in the engine and if the coolant is flushed, replaced when it should be done.

Doesn't the coolant lubricate the impeller and the cooling system?

Looking at Porsche's maintenance schedule, there is no mention of ever flushing the coolant or replacing the water pump. The only maintenance on the schedule is to check the level and antifreeze protection level.
Old 09-23-2015, 07:29 PM
  #37  
Rubik
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Originally Posted by bradbeck
I would expect the longevity of the impeller is determined by how good the coolant is in the engine and if the coolant is flushed, replaced when it should be done.

Doesn't the coolant lubricate the impeller and the cooling system?

Looking at Porsche's maintenance schedule, there is no mention of ever flushing the coolant or replacing the water pump. The only maintenance on the schedule is to check the level and antifreeze protection level.
Yes, but the service manager will try to sell you a coolant flush service within 30000 miles of ownership. Replacing the pump, again, is a feel thing. When engines are readily available and don't cost more than the car itself, I usually replace the water pump when I hit 100000 - 120000 on the clock - good or bad. But with these cars it can be a very costly gamble.

Longevity is directly linked to how much the impeller spends in really hot water I think. Composite will deteriorate over time and even faster in heat.
Old 09-23-2015, 07:52 PM
  #38  
Flat6 Innovations
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Originally Posted by dvs3.6
WHAT IS THE RECOMENDED MILEAGE AT WHICH ONE WOULD OR SHOULD CHANGE THE WATER PUMP?
Every 3 years, despite mileage. The water pump is in service all the time.

No, the mfr doesn't always tell you what's best... If they did it would hurt their ratings. The more it costs to maintain the car correctly, the more it costs to own.
Old 09-23-2015, 07:56 PM
  #39  
alpine003
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It's really simple, you should either test(PH strips or voltmeter) your coolant's effectiveness every couple years or replace it. And preventatively replace your WP on a routine basis with nothing but an OEM unit. The composite construction of some aftermarket units are inferior to say the least. The word "routine" being highly debatable here.
Old 09-23-2015, 09:07 PM
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Rubik
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Thanks Jake for responding to my questions today.
Old 09-23-2015, 11:52 PM
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garrett376
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Originally Posted by Rubik
Thanks Jake for responding to my questions today.
And thanks, Jake, for taking the time to provide such useful information for everyone... your contributions in this thread, and the many others, are greatly appreciated.
Old 09-24-2015, 12:25 AM
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Flat6 Innovations
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Originally Posted by garrett376
And thanks, Jake, for taking the time to provide such useful information for everyone... your contributions in this thread, and the many others, are greatly appreciated.
I enjoy sharing what I've learned.
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Old 09-24-2015, 12:39 AM
  #43  
JayG
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**** mispost****
Old 09-24-2015, 12:49 PM
  #44  
sjg1138
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Does anyone know what the "plastic" impeller is made of on our cars?

"Many claim that 'plastic' Audi water pump impellers are junk. Why?

A) Earlier impellers were composed of a plastic called Durethan. In the high temperature environment of a coolant system, it encountered reliability issues. This plastic was not heat resistant enough at temperatures over 212° F (100° C). Since engine operating temperatures function in the 190-197° F range (87-92° C), this pushed Durethan to it's designed heat threshold. It increased the risk of the impeller cracking or slipping on the shaft. This is why so-called 'plastic' water pump impellers have developed a bad reputation.

Thankfully, European car manufacturers, including Audi, don't use Durethan water pump impellers anymore! Starting around 2000, a new advanced material called PPS was progressively integrated into Audi water pump impeller design and now nearly all new Audis and VWs come from the factory with PPS water pump impellers."


http://www.blauparts.com/audi_water_pump_replacement/audi_water_pump_plastic_impeller_controversy.html
Old 09-24-2015, 12:59 PM
  #45  
Schnell Gelb
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Very informative.Thanks for the tech contribution.
SO which of the current Porsche replacement WPs are PPS ?
And how can you tell? Is the impeller marked "PPS" or Polyphenylene Sulfide?
For example I found this on Fleabay:
"VW OE #: 07K 121 011 B - PPS Impeller "or "OE #'s: 06A121012E / 06A121012G / 06A121031C - PPS"
So it is easy to find a PPS impeller for a VW/Audi .So what about an M96?


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