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MG MGB Technical - Replace the water pump?

I am rebuilding the engine in my 67 BGT. Normally I would replace the water pump, but after inspection, it looks nearly new. Here is a picture of what it looked like right out of the motor.

No play that I can feel or measure in the shaft. Car had 73,000 miles when I got it in 2005. Now has just over 100,000.

Car has never overheated and even coming across the US in August, it stayed well within normal temperature ranges.

Not a ton of money to replace, but also not a hard item to change out (unless you are on the road away from home of course)


Bruce Cunha

Replace it only for the fact that you have a "defective" water pump no matter what its condition.

By "defective" I mean that it is the cheaper model of water pumps.

Yours has a cheap stamped metal impeller. The good ones have a cast iron impeller.

Change it now and sleep better.
Steven Rechter

Given the described and visible condition and experiences with it I'd probably reuse it. I fitted a replacement to my roadster because the original was noisy and sloppy. I thought that was bad enough as it was an alloy casting even though it had a cast impeller, and started weeping on warm-up not long after. So I bought a pukka iron/steel one and carried it around in the boot ... for probably 20 years. I only fitted it a few months ago as I suspected the alloy one might have been sucking in air, but that turned out to be a head gasket. So the alloy pump has gone on the shelf as an emergency spare.
Paul Hunt


So that would indicate that this is not the original water pump?
Bruce Cunha

Almost certainly 100% not original.
Paul Hunt

Thanks Paul. On this car, I have been surprised how few non-original parts I have found. Of note, the pump body is aluminum and not cast steel.
Bruce Cunha

Bruce, Moss has reproduced a high quality cast iron pump with a cast iron impeller and ceramic seals. It's an excellent unit and I would highly recommend that you replace the one that you presently have with one of theirs. RAY
rjm RAY

This thread was discussed between 05/10/2014 and 07/10/2014

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