Hi guys I was wondering if anyone has a trick to testing if the thermostat is working g or not? I have an alloy radiator which is quite big and previous owner said it keeps engine really cool but the gauge doesn't even seem to budge and was wondering the best way to see what isn't working?

The size of the radiator doesn't affect the running temperature. If it doesn't get off cold (assuming guage works) then it either has no thermostat or a dud one.
You should be able to see in through top hose fitting if it has one.

It Def has one as there's wires to it. I was wondering if I can test the gauge at all to see if it's that as the guy I bought the car off reckons it was a new thermo

So you have an electric Temp gauge , is that what you are talking about when you say you have wires going to it ? .The thermostat shouldn't have any wires going to it , does your fuel gauge work properly ?, your voltage Stabiliser might be buggered .

You should be able to use a 9 volt battery to test the gauge .

Just to be sure , it's not a hard job to take the thermostat out , you will soon know if it's fairly new or not ,whilst you have it out you can test it in boiling water to see whether it's opening or not .

just to be clear, a "temperature gauge" is not a "thermostat".

the "thermostat" is a mechanical device that opens and closes depending on temperature, it's under the thing with the rounded top ("thermostat housing") that the top radiator hose goes in to, looks like this (without the 8 drilled holes)



The "temperature gauge" has a "sender" at the front of the head, between #1 spark plug and the thermostat. The sender has 1 or 2 wires going to it. If 1 wire, disconnect it and turn on the ignition and touch it to some bare metal on the engine, the gauge should go up to fully hot, if 2 wires, join them with a paper clip or something - don't hold it for too long, but you should see the needle move

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Thanks mate

Is that at end of thermo housing?

here's your picture, can you take a clear picture of the thermostat housing? the sender is "normally" behind the alternator, but there mightn't be room there so they've put it in the thermostat housing on your model...



either way, the thermostat is the thing that regulates the temperature of the water in the engine, and the temperature sender & gauge is what shows you what the temperature is.... they're not the same thing

if the thermostat is new, the gauge still might not work

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Thanks mate. I've got something coming out of the thermo housing with two prongs to it. Not sure what it is for? There us Def something behind the alternator it has a single wire to it

The single wire one "should" be temperature guage sender unit. The two prong one is probably switch for thermo fan, if fitted.

Thanks mate I hope it's not the sender ad that is going to be a royal pain in arse to change

Looks like sender wire wasn't connected. I've tested the wire and the gauge moved up after about 20 seconds. Now going to run car for 10 mins with it connected to see if gauge moves. If it doesn't could this still be thermostat not working?

If you run the car it should get too hot to touch radiator, around 70-90 deg, depending on thermostat. If not the thermostat is not working correctly.

Ah ok, gauge seems to work and needle moved a bit for the 10 mins I ran it, will give it a good drive on the weekend and see where the needle stops. The guy I bought it off said the needle wont move more than a 1/4 or so cause of the big radiator or some rubbish but yeh. Ill watch it on weekend.

He's talking rubbish, you could put a radiator out of a mack truck in it and should still run at correct temperature. The engine is designed to work best at it's correct temperature.

I agree with this, unless you have an auxiliary heater core behind grille, connected from back of head. These have no thermostat so can cause motor to run cooler on the freeway. I run the Minimatic heater which does this too.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.