switch is driving me crazy!

[softtop]

Car overheated today. Temp went up to 120 on the gauge. The fans were on a break. Let car cool down and then see what happens, fans come on at 100, cool to 90. Fans come on at 92 (as they are suposed to) and go off at 90. How can there be a discrepancy in the 'switch on' times. This is the fourth switch in as many months. Any thoughts? Softtop

[Tyre Smoke]

The temp gauge is a notorious liar.

I wouldn't worry too much unless you notice coolant loss and/or white sludge under the oil filler cap.

[puffsorted2]

Buy a mod-wise twin speed fan kit - superb piece of kit - allows the fans to run after the ignition is switched off as well so its great for shifting heat soak from under the bonnet so should prolong the life of the starter motor and ignition coil which usually get cooked as well as swirching the fans on without the otter needing to get involved. The otter stays connected but just as a backup

>> Edited by puffsorted2 on Friday 10th February 11:23

[harrow_chim]

Have you checked out the fan connectors - might be badly corroded which will give an intermittent problem. Dont think switches go that often so has to be another explanation.
Nick

[Cider Andy]

The temperature gauge operates from the sender mounted on the engine, so measures coolant temperature by the thermostat. The 'otter' switch is controlled by the temperature of water within the radiator. The two temperatures will tend to be similar whilever the thermostat is open, there is enough coolant in the system and the water pump is working properly. But when starting up from cold, for example, the water in the radiator will remain stone cold until the thermostat opens, by which time the engine coolant temperature will be up at around 80°C.

[dlewis]

My comments are:

at 120 degrees C it will be bubbling and exiting the header tank

have you checked for circulation? either side of the thermostat or at the rad after warming up?

Dave

[softtop]

Thanks Guys for the responses. The flow appears to be ok, the issue is why the erratic behaviour?

I think I will get the kit. Got the hot start, great piece of additional hardware.