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Radiator cooling fan stat switch


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I am looking to replace the standard radiator for my GT6 with an after market ally rad and need to know which thermostatic fan switch should be fitted, i have a choice of four different temperature ranges as follows -

On 88 degrees Off 79 degrees
On 82 degrees Off 68 degrees
On 92 degrees Off 87 degrees
On 88 degrees Off 74 degrees

The car will be driven in the UK on the roads only. I've had a quick look in the owners manual and the information for the cooling stat is opening temp 79.5 to 83.5, fully open 93.5 to 96 degrees.

Has anybody fitted an ally rad and if so what thermostatic fan switch did you fit?

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Ok guys more info to digest.

The rad i have has a M22 threaded switch mount at the top but my thoughts are that it would be more efficient at the bottom because the hot water comes in at the top and cold out of the bottom so if the radiator struggles to cool the water then the thermostatic switch situated in the bottom would register this and start the fan.

Is this correct or am i missing the reason why the thermostatic switch is mounted in the top of the radiator OR do you have a higher on temp switch fitted to the top to compensate?

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it will be a 'suck it and see' scenario.

as said already the further along the cooling circuit you go the lower temp switch you need because of the thermal gradient across the radiator.

play safe to start and use a low temp switch.

if the fan comes on too early get a switch with a higher rating.

they don't cost that much,you have to settle with what suits the engine and not what you think it needs. :)

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royboy66 wrote:
I'm running a switch in bottom of Golf rad,  95-90  


That sounds high. Modern engines often switch the fan at 100 (or even 105) but that's based on engine coolant temperature (i.e. in the thermostat housing) which will be a lot hotter than the bottom of the rad. That said, as long as the bottom hose is colder than your target engine temperature it will still cool it, so it's not at all unreasonable to have the fan switched at a higher temperature than the thermostat, which is 82 or 88 IIRC.

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