Welcome to our Site for MG, Triumph and Austin-Healey Car Information.


MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - electric water pumps

I suspect an answer to this thread would be, why bother? But a thought non-the-less. I saw an ad, for electric water pumps. I thought they would fit where the present water pump might be on an engine, but no, the are added to the bottom hose usually, and would propel the water. So why? quick warm up, thermostatically controlled, (like the electric radiator fan?)reduce power consumption,( in this case, maybe only useful in racing situations where you want ever little bit of power to drive the wheels.) My thought was, perhaps it still might be a thought, for todays modern engines coupled with electric engines in the sense that there is a reduction of total emissions? Trouble is you still need to generate the electricity to drive these things! Mike
J.M. Doust

Usually they are fitted to thermo siphon cars, or cars with real cooling problems, so bearing the octagon P and J types and the SVWs respectively. They work well and will give you good flow at low RPM.
Stan Best

Always wondered why these were not more prominent on today's cars?. With all the issues on fuel economy you would think the old power robbing pump would have been replaced with an electric pump years ago.

Anyone have the minuses of using one of these?
Bruce Cunha

Unlike an electric cooling fan an electric coolant pump would almost certainly have to be running all the time. And again unlike electric cooling fans the higher flow rate of the mechanical pump probably *is* required at higher rpms. Electric cooling fans running full-tilt is fine because they only come on when needed. At the very least an electric coolant pump would need to be variable speed, or it would be running full-tilt when it wasn't needed. All this makes any savings in mpg marginal, to me.
PaulH Solihull

When fitted to pre war cars they are usully under manual control via a switch. So when your blown J4 gets stuck in traffic or you are climbing a hill in your SV you can keep the water temperature gauge out of the red. I suppose for modern cars the all knowing ECU could control it as one more thing to go wrong
Stan Best

I have fitted the davies craig EWP 115 to my V8 MGB along with the digital controller. You can set the target temp and the old thermostat has to be removed. The EWP pulses 10seconds on, 20 seconds off until it reaches a certain temp then 10 seconds on, 10 seconds off then it goes to running constantly when the target temp approaches.
My reason for going down this route was the need to counter rotate the later interim water pump.
Very easy to fit and it also controls the electic fan.
It needs a bit of fine tuning with a smaller restrictor plate as it runs slightly on the cool side when cruising, Engine capacity is now 4.8L

M Rawlins

That's interesting Mark, thanks for the input from a 'user'. I thought that some variable control was in order, ultimately, some programmed 'chip' will do this. Things to come? Worth a thought then on the large engine when space and logistics go 'against the grain'. Mike
J.M. Doust

An engine-driven coolant pump flows at a rate that is dictated by engine speed. If the pump speed is too high, then the coolant circulating through the engine doesn't have sufficient time to absorb the heat, and it also flows through the radiator matrix so quickly that it doesn't have time to get rid of the heat that it absorbed from the engine. The result- overheating. The rationale for utilizing an electric water pump is that its flow rate is independent of engine speed, and that's why racers like them. The drawback is that you have to use a power-robbing larger-output alternator in order to produce the needed electricity required to rum the pump.
Stephen Strange

Stephen while we are on the subject. I concur entirely with your thoughts. Tell me this why is it that we have on many MG's, and I am not talking of the more modern ones, an oil cooler but no thermostat as standard? Mine had a cooler (1972 GT), but it had been disconnected because of a leak. I have yet to replace it, but engine temp has always been good, and at the correct level. I use a summer, and a winter water thermostat.In your 'Book' you suggest that we may all be overcooling our oil under 'normal'circumstances, and this is probably true, ( In fact I have just thought of an additional gauge for the car, oil temperature.) Unless I am going to stress the engine considerably, perhaps I do not need the oil cooler? Mike
J.M. Doust

FWIW, I've removed and shelved my oil cooler. I also run a 195F tstat year-round with no problems. (Summer temps in NC regularly reach 95-100F). I think that not only is over-cooling the oil a common problem, but also over-cooling the engine itself....
Rob Edwards

Mark Rawlins, any chance of a picture or two of your installation ? I aim to go this route when my Rover V8 engine water pump gives up the ghost. Barrie E
B Egerton

Oil cooler was optional at the beginning. Word is it was only fitted as standard to counteract owner paranoia of falling oil pressures under circumstances, itself a factor of fitting an oil pressure gauge in the first place. The thing is, it really only functions when you are travelling forwards, so when stuck in traffic the cooler doesn't function anyway. In fact it can act as an oil heater, as even in still air a significant amount of hot air from the engine bay comes forwards to be recirculated through the oil cooler and rad, a lot more if the air current is from behind you. I remember on a Bath to Bournemouth run many years ago when they did interviews at the 'finish' line, we had a bit of a tail breeze, and people were panicking about rising temperatures and dropping oil pressures so they had to skip a load of interviews to keep people moving.
PaulH Solihull

This thread was discussed between 31/10/2011 and 04/11/2011

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now