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Fan Thermostat Switch


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Hi all

 

Wanting to make my fan come on automatically on my zetec blacktop. I have been looking at the thermostat switches from the likes of Burton Power, these look relatively simple as they just slot into the existing cooling system, however at £70ish they are not cheap.

 

My question is - can i use the top sensor in the zetec thermostat housing and use something like this

http://www.ebay.co.uk/itm/180F-ELECTRIC-FAN-THERMOSTAT-SWITCH-1-4-NPT-BRASS-SENSOR-PROBE-CHEVY-350-383-/331810356926

 

It seems this would be ideal given it is not currently being used (temp dial is using the bottom one). However is this the best place in the cooling system to have this sensor.

 

Thanks

Simon

 

 

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On my pinto i added a thermostatic switch into the thermostat housing. It works but it has a quirk that it often makes the fan come on after the car has stopped. This is because the engine block has a lot of residual heat unlike a radiator which loses it much faster. So when it stops the heat builds up and turns the fan on. Once the engine cools a bit it turns off. Normally a couple of minutes.

 

It's not a big problem and works as it should when driving.

 

hth

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Guest mcramsay

Having the fan come on when you turn the engine off is nothing but a good thing, you can get hotspots and localised boiling of the coolant due to the loss of coolant flow and heat soak of the block into the coolant, having the fan running will cool the coolant in the rad which which should start a little natural circulation of the coolant... in theory anyway

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If the hot water is at the top of the engine that's where it will stay -- needs to be hotter lower down for a thermo-syphon to work. The only advantage gained is the fan draft may cool the block a little after passing through the cooled rad. Biggest down side is the current drawn from the battery with no replacement from the alternator, best to wire the fan stat to be controlled be an ignition feed.

 

NW Hoods had a brilliant wiring diagram for high load fans.

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The least useful place to have a fan switch is the block closely followed by in the thermostat housing attached to the block. Best places are close to the rad in either supply or return pipes or in the rad itself. There are arguments for each of these latter three being the best but they all do the job. You will find that the temperature the fan switch is activated at will be different for the position it is fitted. Higher if fitted going to the rad or not so high if in the return. The two positions in the blacktop stat housing are usually occupied by the temperature gauge sender and the ECU engine temperature sender. Mine is fitted in the rad to engine return, on at 90, off at 85.

 

Nigel

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Cheers guys

Sounds like the rad option is better but more expensive - but probably worth the extra. Just a shame not to use the existing connector in the thermostat housing however if i wire this to the megajolt it will no doubt come in handy when i get round to a rolling road session

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