Replacement radiator fan thermostat

[AndM]

I think I might need to replace the radiator fan thermostat as the fan isn’t coming on but runs when wired directly to battery. I have checked the wiring and power is getting through the fan down to the thermostat. A quick look shows OEM part not available but possible substitutes have only two terminals where original has three. That is power through fan, earth to earthing block on inside front wing and short wire from thermostat to collar around thermostat where it seals to radiator body. Not very familiar with electrics, can anyone tell me why the existing thermostat has two earth connections (one to earthing block and one via collar) and if I replace with a two terminal thermostat is it ok for it to earth to the earthing block alone without having an earth to a collar on the thermostat itself. Any help much appreciated.

[capriblu]

I've only ever seen two terminal fan switches on the betas that I have had? (Single earth to body mounted terminal block in front corner near headlight).  Any M22 x 1.5 radiator fan switch rated within the original 87/92 range will do the job. You can choose a lower temperature switching item if you want the fan coming on earlier.  Loads on ebay to choose from.

[Thotos]

The collar should be separate to the thermo-switch so can be transferred to the new one. It's there to earth the radiator. Before changing your radiator switch, check your water thermostat. If that's not opening, the engine will get hot but fan will not come on as the hot water is not reaching the radiator.

[Neil-yaj396]

This thread gives details of my troubles with the switches, including compatible part numbers;

http://www.betaboyz.myzen.co.uk/forum/index.php?topic=2864.0

[AndM]

Thanks for help and advice. Much appreciated. Radiator getting red hot so seems likely thermostat all ok. Confirmed fan runs when earthed to battery. Confirmed power arriving at thermo switch via fan and that both earths from thermo switch are good so looking very much like thermo switch itself. Just had radiator re-cord and was all working fine before. Will order a replacement thermo switch and test old one when I take it out. Was hoping not to have to drain down and mess about replacing but looks like that is the only option left. Thanks again for replies.

[Neil-yaj396]

I found that if you loosen up the old switch first and have the new one to hand you can swap them quickly, only losing a pint or so of coolant.