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MG MGF Technical - Help re' side intake fan re-wire

I have read somewhere on this BBS about changeing the wiring for the side intake fan as it no longer works with the Emerald ecu. I can't the thread in the archive so if anyone can offer any ideas I would be grateful.
Nik& Anita

Could be Erik.
Not mentioned on his ECU mod site though.
I recall he installed an extra switch to power the fan _by hand_ if required. Not sure whether he found a final solution with it.
Dieter K.


I think going manual is the only way to rig the fan.

Since fitting the Emerald I have not had the fan connected either, with no side effect. Of course the Elise does not have a fan in the first place and seems to work pretty well (Well, except for the standard HG issues).

There is the option to do as Rob has done with his electric waterpump and fit a time delay relay.

I would be interested in hearing what you decide to do.

(I believe that Kingsley has not worried about reconnecting the fan either!)


BTW, when I asked Dave Walker about fitting a 4-2-1 he suggested the Emerald map would not necessarily need to be re-mapped.
tim woolcott

Dieter's right, Erik's your man as I too recall that he'd managed to put together a circuit to control the engine bay cooling fan.

Having said that, it should be quite easy to put together a circuit to control the engine bay fan Nik - a simple Whetstone bridge should do the trick. Dieter's sensor web page should give you the resistance values needed to put it together :o)
Rob Bell

Thanks lads. I am going to give it my best shot over the next week or two. I did think of a one touch button to give a set time for the fan to run, either with the engine running in traffic or when turning off the engine. What do you think?

Hi Mik,

bear in mind that this fan action should be _only_ to cool down the fuel lines and prevent from boiling fuel.
Air bubbles due to boiling fuel could cause a stalling engine.

So IMO it's not bad to have a circuit similar to the ECU function.
Measure temperature and let it cut in within a wanted temperature range.
(Temperature sensor could be a simple bi-metal switch i.e.)

1. The fan could run always above the max temperature while the engine is running
2. If the engine is shut down, then combine the temp. max with a timer.

I think *NE555 - Tony* is your man to provide the timer circuit ;)

Dieter K.

The operation logic of the standard fan is as follows:

If ambient temperature exceeds 75C, then the fan comes on for 3 minutes - or until the ambient temperature drops below 65C.

The fan is operational for 8 minutes after the ignition is switched off, and fan operation continues to follow the above logic.

Should be easy for someone with an electronics 'bent' to knock something suitable up! :o)
Rob Bell

Following up on Robs comment does anybody know the location of the thermostat which controls the fan?
K Marshall

It's located ahead of the coolant expansion tank ie on the right side of the car as you look from the boot access.
Neil Stothert


Apologies for dropping into this thread rather late.

There are a couple of solutions, like turning on the fan manually, together with the radiator fan in the front (fuse and wires !!) or installing some simple electronics wich will do the trick.

I bought a really easy kit ( which has two potentiometers:
1) setting the temperature to kick in
2) setting the temperature difference needed to stop again.
I installed the kit in the interior of the car, so I could tune and check it just after installation. The sensor is positioned in the engine bay, where the other sensor was located.

Drop me a line if you need more info.

This thread was discussed between 30/04/2005 and 09/05/2005

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