j-mann

Yesterday I replaced my water pump at 53K. There were no broken fins but when I took a pair of pliers to the impeller, the fins just broke off with barely ANY effort. My heart jumped a little knowing how close I came to having them buried in my engines coolant passages.

Macster

You didn't come anywhere near close to having them come off in the engine. The odds of you just picking the time to replace the water pump just before the blades were due to fail is astronomical.

The blades move gallons of hot (I've seen sustained coolant temps of 226F) coolant per minute of engine run time. They speed up and slow down in sync with engine rpms. They are tough.

They can fail from two causes: One is the coolant system has a pressure leak and without pressure the water pump blades experience cavitation which can be very damaging to blades to the point the cavitation causes mechanical failure of the blade; Two is the water pump gets some play and the noise (admittedly subtle at first) is ignored -- every so often someone posts about a suspected water pump noise and wants to know how long he can continue to drive the car -- and the play increases to the point the blade edges come in contact with the engine water pump cavity. The blade edges run very close (for efficiency's sake) to the surface of the water pump cavity in the engine block and there's not much room for a wobbly water pump impeller to wobble.

Sincerely,

Macster.

j-mann

[QUOTE=Macster;9453024]You didn't come anywhere near close to having them come off in the engine.

What a relief.

targa996

Just out of interest - why did you decide to replace WP ? And what did it cost ? (dealer or indie or self ?)

j-mann

I replaced it as a preventative maintenance item - and I'm really glad I did. I did the work myself.

aviography

OP,

Did you use the 996 pump or 997 pump?

BTW, isn't it nice to have an unique factory color?

Dharn55

There is some conjecture that non-OEM coolant will soften and damage the plastic of the impeller along with other "European" plastics, but I have never seen any real proof and/or documentation of this and don't really buy it.

j-mann

THE 997 PUMP? Why am I just NOW hearing about this? Seriously - educate me.

j-mann

I love the viola - post more pics

dennis hiip

CAUTION!!!I recently changed my WP (MY 2003) and was sent a 997 WP from Sunset (supposed to be replacement for the 996) However the impeller was slightly lager in diameter (aprox 4mm) and would not spin freely inside of the housing. Had I not checked the rotation before starting the car it would have been a bad scene.

street rod

997 wp installed in my car with no issues.

dennis hiip

Yes, Ive read where it's now common practice to use the 997 WP in place of the 996 WP. On mine, we measured the impeller and it was 4mm larger in diameter. When I called Sunset Porsche and told then, I was put on hold while they rechecked and they came back to apologize. They replaced and paid for return postage. So, I don't know what's up with that, but I would measure the impeller prior to install.

Flat6 Innovations

Look for a water pump tech article in Excellence in a couple of months.. They just interviewed me on the topic yesterday.