Water pump

T

teemck

Member
Hi can anyone tell me the difference with these 2 water pumps and does it make any difference? the one on the left is new has a plastic rotating whilst the other has a metal rotating blade are they both as good?
 
Can seem too load image basically one end on the water pump has a black plastic the other pump has a metal end?
 
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The theory
Plastic impellers tend to have a more efficient profile for improved water flow
Some reports of the impeller slipping on the shaft but unlikely to occur if the pump is changes with the cam belt
If engine block ever freezes up the impeller is likely to spin and lessen risk of loosing cam belt
Traditionally an 'OE' design

Metal impellers have never been known to come loose
Pump performance will be reduced marginally but never known to be a problem
No freeze protection
Traditionally aftermarket design

Cheers Spike
 
I bought a genuine water pump and it is a metal impeller.
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Just for reference :)

edit - I've just checked the pump and in fact it is a plastic impeller.
pump.jpg
 
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I have a memory that Tony (of A2 Cars) fitted a metal impeller pump by choice on my FSI. I do know plastic impellers have been known to have fins break off, in fact I think there was good picture here recently.

Andy
 
I have also heard scare stories of plastic impellers spinning or breaking however my experience is different. I have been changing cam belts and water pumps on audi's for 30 years, I must have done 20. In my recollection I have never even seen a metal impeller. Plastic has always been what came off and what I put back on, never had a problem.

Trevor
 
TAABVW said:
I have also heard scare stories of plastic impellers spinning or breaking however my experience is different. I have been changing cam belts and water pumps on audi's for 30 years, I must have done 20. In my recollection I have never even seen a metal impeller. Plastic has always been what came off and what I put back on, never had a problem.

Trevor
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Hi ive just removed water pump and replace is it worth fushing the whole cooling system radiator ? is it easy?
 
Depends on the state of the old coolant. If the old coolant came out relatively clean then I would see no reason to flush the system.

The radiator cooling circuit will be isolated from the engine cooling circuit by the thermostat. Hence with the water pump out you would only be flushing the engine loop. If the old coolant was "sludgy" then it is the radiator loop that would benefit most from flushing given the small bore sizes, this would be a job independent of the water pump.
 
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