Is the spinning impellor metal of a non metal part ?
I really would doubt that .015" is going to affect the pumping efficiency at all. That is nothing compared to the total volume of the pumping chamber. THat sealing O RING looks crumbly ?
Is the temperature of the engine O K ? That sealing O RING looks worn ? Is water running out of the pump casing ?
I found something.
(My impeller is made of rubber.)
For the last 6 years, I was changing my raw water pump impeller every two years using a Sierra brand unit. It always worked well, but not this time. I discovered that THIS new Sierra impeller was 1mm (0.04'') shorter than a brand new Volvo unit that I just bought to test.
My problem was that the pump was not priming itself, even using a bucket with 2 hoses to test directly at the RWP.
It should have pumped because I was feeding water from the Volvo rinse port, not the outdrive leg.
I put the Volvo impeller in, and it worked perfect the first time. So, those non OE impellers are made with a lousy tolerance I believe.
PS: Before buying the Volvo part, I changed the bearing seal and a new O-ring on the casing without improvement. The impeller was really the problem.
