Radiator Thermo Switch

Hello all,

I've got a 1978 1.1cc Golf where the radiator thermo switch does not cut the fan in even when the temp gauge climbs way up to the top. The fan itself is ok 'cos I've tested it and because of the switch problem I stuck in a manual override. This is ok but I'd still like to have a thermo switch that works.

Can anyone recommend a later rad thermo switch that cuts in at a lower temperature than the original MK1 switches but will still fit a MK1?

By the way, the thermostst is ok and the radiator is virtually new so I think it's the fact that the termo switch is designed to cut in at 92 degrees. That's almost boiling and way too high in my opinion.



Cheers

92 degrees is probably correct - remember that the boiling point is higher when its under pressure - it probably won't boil until 110+

Thanks for the reply…

True, 92 degrees is probably correct for the car but with the temp gauge nearing the orange bit at the top I would have hoped that it would have cut in at that stage. I might do the saucepan test on the switch and see if it does do anything at the temperature it should.

I'd check there is not a blockage anywhere and that your water pump is actually doing it's job. 92 is the correct opening temp

Hi,

had this same problem the other day. I used a thermoswitch from a mk2 polo, the temperature rating is the same.

On the plus side, they seem better designed in that the contacts are well protected - on my old one they had just corroded away…



If there is a suitable OEM switch that'll operate at a lower temperature, I'd be interested. I wonder if using the switch from models with a two-speed fan, and connecting up to just the first fan speed would give the result you're after?

to test if its the switch or not, disconnect the 2 wires and bridge them together. if fan runs its switch, if not its the wiring or the fuse.  also check you got good coolant flow thru the rad, when it gets to 3/4 feel the sensor end to make sure its as hot as t'other end

Hi all,

Well, I tested the original VW rad switch that I took out some time ago by dangling it in a pan of water with the pins connected to a multimeter watching the resistance. Before the water started to boil the resistance dropped to zero so that switch was good.

I tried the same test with the newer switch I had put in the car and nothing happened even when the water started to boil = dodgy switch.

I stuck the original VW switch back in the car and the fan cut in on a hot day long before I myself got anywhere near having a seizure.

It just goes to show, the original is still the best and heaven knows what cheap crap we're buying out there as replacements..


Cheers for all your replies!


C