Direct fan switch

[tyasman]

I'm sure there is a simple answer to this one, but electrics are not my strong point. I already have a switch on the dashboard that allows me to manually switch the cooling fan on, but the ignition obviously needs to be on for the fan to work. I want to switch the fan on but with the ignition switched off, so I can cool the engine in a traffic jam with the engine and ignition switched off. I don't particularly want to run a wire all the way back to the battery in the boot. Where in the engine bay can I attach the wire so that is always on a live circuit to the battery? Has anyone got another way of achieving the above?
Thanks for replies.

[billwill]

A brown wire runs from the starter solenoid to the fuze box. This is the main unswitched feed from the battery.
You should take your fan feed from the opposite end of one of the fuzes fed from that brown lead.

i.e unswitched but protected by a fuze.

[vernon.taylor]

Salut

Maybe an unknowledgable thought - with the engine off the water pump won't be circulating the coolant, so will the fan/radiator actually cool the engine ? Won't it just cool the water in the radiator ? Isn't it better to keep the engine running at idle ?

@+

Vernon

[tyasman]

Thanks Vernon,
Nice point and a knowledgeable one!
Time to rethink.
The engine temperature rises when car is stationary, even when the fan is on.
I need a bigger fan!
Simon

[ricarbo]

I find that if you stop the engine hot, the temperature gauge rises, presumably because the hottest water now has a chance to rise to the top. But since the engine is stopped it will actually be cooling down, so the gauge is being misleading.
If the fan can't keep up when the engine is running but the car is stopped, you have a problem. I'd start by flushing the radiator with 'Radflush', and then refilling with a minimum of 50% antifreeze to keep corrosion down to a minimum.
regards
Richard

[oldelanman]

The engine temperature rises when car is stationary, even when the fan is on.
I need a bigger fan!

If it's the OE Kenlowe fan check that the blade is fitted the right way round. See here........

lotus-electrical-f38/electric-fan-t28986.html

Scroll down to the last few posts

[rgh0]

With the engine off you will get a slow thermosiphon circulation with the cooler coolant in the radiator sinking down and flowing to the block through the bottom hose and the hot coolant in the engine block flowing into the top of the radiator. Having the fan on will help this process a little.

Generally if your fan is working ok the engine should cool down faster at idle with the pump forcing the circulation than with the engine off

cheers
Rohan

[gherlt]

Apart from that with a fan you move the hot air in the engine compartment and therefore you bring down the ambient temperature, so you help cool down the engine block ...