Temp sensors

[Jonathan]

Just a quick one, there are three sensors on the front of the engine block, in the cooling pipe, one black, red and gray, I think the black one in the bottom is the temp gauge, I assume one of the two on the top is the fan switch (not shore which) but no idea on the third one. Dose anyone know which one is which?

Thanks, Jonathan

[MRMENDER]

The rad fan sensor should be on the rad.
The other two are to do with the Pierburg carb. One (Not sure which) Is still needed even if you have a Weber carb fitted, as its to do with the heated inlet manifold

[Jonathan]

So where dose the signal for the temp gauge on the dash come from?

[MRMENDER]

As you say I THINK its the one on the bottom. Easy to find out. Put ignition on, remove the wire from the sensor and put it to the engine block, or the negative on the battery. You should then get a full sacle deflection (Right over to hot) on the temp gauge

[Jonathan]

Cheers, I'll try this first.

I'll give a bit of background to the question, I'm having an issue with overheating, or so the gauge reads. I've changed the expansion cap, top pipe to the expansion bottle and thermostat. Can't see any leaks anywhere, did a compression check, all fine. Checked returns and there plenty of circulation from the pump. The fan cuts in and out fine. Just the display in the car is overheating. Any ideas any one?

[hiltow]

If you stand at the front of the, car facing the engine, and look at the right hand side of the cylinder head, you'll see a metal flange where the smoking pipe-shaped heater hose connects to.

Look down the back of this metal flange and you'll see a small brass sensor screwed into the back of the flange - this is the sensor that works the temperature gauge on the dashboard.

[Jonathan]

Ive had a look today and there is no metal flange on the side of the block, mine is plastic with no sensor in it. I did however bridge the one I though was the temp gauge (the bottom black one) and got full scale reading on the dash, so that that one. Also I got part numbers off all three sensors as I have the originals, black one is 251919501a which description when i search it is temperature sender. The other 2 are red 251919369b and 191919369b gray.

Also looking in the Haynes the sensors are in different places on carb and injection engines, mines carb. And non of these three are fan switch as that's is the bottom of the rad. So I'm thinking they where something to do with the auto choke before I fitted the webber.

Thanks for the info guys.

[go-for-it1]

Grey and Red ones are for heating hedgehog in bottom of inlet manifold and auto choke on pierberg, think the hedgehog is the grey one.

[klittle]

Just a quick idea that happened to me recently, I fitted a new thermostat when I changed the head and my engine temp went up to over half, turns out the thermostat was sticking and caused it to run too hot and has now forced me to plan an early engine change. Worth while checking as mine never boiled but as it ran too hot it caused no end of damage before I realised what it was. Put new thermostat in pan of water and check it opens at correct temp before fitting.