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MG MGB Technical - replacement water pumps

Hi Guys,

Going to have to change leaking rad & thought I would replace the water pump while i've got it off.
Are the cheaper ones as sold by , moss, mgoc, hive etc any good at around 25-29 any good or are the so called OE ones online at around 50 really that much better ?
Your advice would be appreciated.
Thanks Ken
k proud

Which ever one you choose ensure it is fitted with a cast iron impellor much more efficient than a pressed metal one.
jim soutar

Water pumps are one thing that has more than one origin. Some are pretty rough, others quite good - and there's no correlation with prices.
Which are the ones you are referring to as OE?
Paul Walbran

I'm using a Moss supplied cast one on my 1950 stage two 130hp "B" engine and on several customer cars. All are working as they should.
jim soutar

Ken, have you any worries about the state of your water pump? If not, I would keep the old one.

About fifteen years ago, I was convinced my water pump was on its way out. There was a strange rushing noise which was from that region. I bought a new pump but the noise turned out to be the (relatively new) fanbelt. I left the new pump on and bought a new fanbelt too. A couple of years ago, I had to change the bottom hose and discovered the new aluminium pump body had been slowly but surely eaten away by corrosion. The bearings and seal were fine but the outlet was 75% gone. I put the old cast iron pump back on and it's been fine.

Let sleeping dogs lie!
Mike Standring

I needed to replace what appeared to be the original cast iron pump and received a cast alloy one - which incidentally still had a cast iron impeller, not the pressed type I have seen elsewhere. This was a terrible fit, I had to oval one of the holes and lower a boss round one of the bolt holes before it would fit. Then shortly afterwards I noticed it was seeping during warm up, but not all the time. When I finished cussing I bought a proper one this time - cast iron body and impeller, ready for when the alloy one failed. Some 20 years later I still hadn't needed to fit it, but did so as I had a cooling system problem and wondered if the pump was sucking in air. It wasn't (it was the head gasket blowing slightly), so I've kept the alloy one as an emergency spare.

Unless it is actually leaking, or making a rumbling noise and the spindle moves up and down, leave well alone.
Paul Hunt

The Moss cast iron water pumps are made to a very high standard and I highly recommend them. The alloy pumps are known for breaking off where the alternator attaches to them. RAY
rjm RAY

Thanks for the advice guys, having taken the old one off it does have a cast impeller,and seems to be in good order . no leaks or movement on the shaft.
I had pretty well decided to refit it and reading your notes has convinced me. Thanks a lot. ken
k proud

This thread was discussed between 19/10/2014 and 21/10/2014

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