Wiring a Rad Fan Over Ride Switch

Why are you buggering about with a manual switch when you have a proper thermo one already?

But the thermo-switch will do that for you..?

Famed for it through lack of maintenance. If you are concerned, for a new themoswitch. 300TDi Landrovers were meant to be bad for HG and mine did over 2 years of hard abuse with a heavily turned up pump and turbo and a very heavy right foot. Never gave me a minute of trouble. Because it was well maintained. Same with my Cherokee. Keep the cooling system in good condition rather than try to 'fail safe bodge' it better. I was going to do what you want to do on the Cherokee because it used to run hot. But instead I replaced the radiator and fan coupling, flushed the block and heater and now it's as steady as a very steady thing. Use your new switch for some mahaosive LED light bar or something

Thanks for the suggestions, the cooling system is in good condition, it's been well maintained, (the interior, however!) and it doesn't overheat.

The electric rad fans are aftermarket and originally had the thermocouple taped to the outside of the bottom hose, I've replaced that with a in hose one.

The Delica originally had a viscous fan, which works at low vehicle speed, ideal for off-roading.

I'm adding braces to my belt because, I found that neither thermostats or temp switches are very accurate and for the few pennies and a little bit of effort I can have an extra level of protection. I expect I'll rarely use it, but better not use it, then regret not fitting it after it's over heated in the Atlas mountains.

As said I'd ensure the cooling system is fine instead of the fan switch.

Like the Delicia the Mondeo 3.0 V6 I owned was renowned for blowing HGs, shitting out water pumps and even on occasions having a shot bottom end. So how did my example fare from 110k ex-SOCA car to when it got written off at 262k?

Absolutely fine. I'll not lie, there were times it got hot (not red hot). But that was down to a hose going on occasions, a rad tank going as well as an expansion tank, in addition to the fan controller dying. The latter was down to an iffy mechanic who botched a clutch change at 210k. In that time I took it to Spain, France a few times as well as it knocking up around 200 miles a day for quite some time.

I didn't also drive the car once I knew it had a problem ; how many people still ignore the issue rather than find out what it is?

All I did was ensure I had decent coolant in it (Ford's 10 year coolant) and used decent hoses/rads. That was Ford mostly but the rad was a Nissens. Oh, and changed the oil without fail every 10k.

Generally, if I saw a perished or splitting/leaking hose I'd change it. I learned my lesson from the previous botched V6 I bought. In my defence the first one was very cheap, but ultimately very costly once 4 months of ownership had passed.