Mk1 Golf overheating

[trooper1212]

Had a nice flashing red light and coolant bubbling out of the header tank this morning. After I opened the bonnet I noticed the fan wasn't going, so I'm guessing this is the culprit.

Likely cause? Is there a fuse gone somewhere?

[KITT]

Could be. I have no idea as to the type of fan on a Mk1 Golf, but assuming it's electric and controlled by a thermo switch, the easiest test is to locate the thermo switch (normally on the top of the radiator) and short the 2 wires plugged into it together. This should activate the fan. If it doesn't then either a fuse or the thermo switch has gone.

[weed]

Test the rad fan by jumping the terminals in the harness plug at the thermoswitch. If the fan runs then the fan's ok. You can test the thermoswitch by Ohmeter as it should be open when the value recorded on the body is exceeded, eg 98* C.I would change the thermostat if that has not been done recently. Check around the waterpump for coolant seepage as well although they generally cause the cooling system to haemorhage when they do fail.
m.

[bangernomics]

I've had several of these thermoswitches fail over the years - hope you haven't cooked the head gasket.

Last time the one on my Mk1 failed (in rush hour traffic) I turned the heater on full blast, and that just kept the temperature out of the danger zone until I got out of town.

[trooper1212]

Had the thermostat switch replaced and all was fine...

... for about 20 miles Driving home I had the fan fail again. Whacked on the heater at full blast and after a bit of experimenting, it appears that driving at 83mph is the best compromise between heat build-up and displacement when your fan isn't working. Good job there wasn't much traffic on the M1!

Had a play this morning and it seems to be a dodgy connection, a couple of new spade connectors and all seems fine for the time being, but I'll keep an eye on it.

As for the head gasket, I'm not too worried, it not a standard head nor a standard gasket, so it should be ok