MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

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 - twin electric cooling fans

just imported my UK mgb roadster to the US, mine is a 1980 model with 1 electric cooling fan. US spec cars and UK V8's have two. Has anyone added the extra fan to a UK car? my concern is the extra load on the radiator mounted switch, what about fitting the fan motor relay? although the US wiring diagram doesn't show it.
short of buying the V8 wiring loom with extra connector i was planning to piggy back the extra fan into the circuit.
Look forward to comments from anyone out there
jon
j Whitehead

Hi Jon.

I would recommend using a relay for one or two fans.

The wiring isn't difficult, take a look at :

http://www.mgcars.org.uk/electrical/relays.html

Don
Don

Jon
I piggy backed the second wire in 1982 and it's been fine. Use the V8 upper mount for the second (N/S) fan - it's different to the O/S. The wiring to the switch and fans is 'heavy duty' anyway. There are some handy bullet connectors under the front panel.
Don is quite correct, the 'proper' way is a relay, but I took the lazy man's route to test it and never needed to 'switch'.
Dave
Dave Wellings

thanks for the reply guys, this is the first time i have used the BB and its amazing how much of the world is covered!! As i've currently go the bumper and grille off the car, i'll probably remake the front loom and wire in the relay.....thanks again
jon
jon

American cars had two fans without a relay so I doubt load is an issue, except possibly with a poor quality replacement radiator switch. The V8 uses a much lower rated thermo switch and always had a relay. However there is evidence that some 4-cylinder cars did have a fan relay for a short time right at the beginning. It was a curious 3-terminal relay but you can achieve the same effect using a four-terminal. I'd just parallel connect the extra fan. But if you want to fit a relay extend the green on the thermo switch to the 30 or C1 terminal on the relay This needs good connections at both ends as it will be carrying the fan current instead of the thermo switch. Remove the black/green wire going to the fans from the other thermo switch terminal and connect it to the relay 87 or C2 terminal. Connect the now empty thermo switch contact to the relay 85 or W1 contact. Connect the relay 86 or W2 terminal to a good ground.
Paul Hunt

My '80 has only one fan, the result of at one time having the BL A/C unit installed. I have not had any problems with overheating, even in city traffic. You might want to leave it as is until you know if it's needed at all. The climate in Houston is the same as over here in Pensacola, so I'm operating in identical conditions.
R. L Carleen

This thread was discussed between 18/10/2004 and 19/10/2004

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.