Coolant problem

[Jcb]

Thankyou for your help guys. I'm used to gauges sitting in the middle so to see it rise to 90 odd is disconcerting to say the least.
I've put an 85/90 switch in and the fan kicks in at 75 on the gauge. Coolant seems to be circulating so I'll get it back together and try a road test.

[dandywarhol]

Tested the new switch suspended in a boiling pan of water and no circuit so I guess that's duff too.
Any UK options available.
Removed and checked thermostat works.
Where abouts on temperature gauge does anyone else's sit?

Highly unlikely you'll get a fan thermoswitch to close circuit in boiling water. A cooling system is pressurised to raise the boiling point of the coolant - approx. every pound of pressure raises the boiling point by 1.5 deg. C, so the fan thermoswitch is probably designed to close circuit around 105 deg.C - impossible to achieve by testing it in 100 deg. C boiling water, or less if you're above sea level (as most of us are )

A 1 BAR (15 psi) pressure cap valve won't open to the expansion tank to around 120 deg.C. Plenty room to play with even in really hot weather Running the engine cooler than it is designed to only increases engine wear.