So I'm out today, leisurely drive, been on the go for half hour or so when I glance down and see the temp gauge off the scale!! Literally past the red even, almost at the 12 o'clock position!!

Cr*p myself almost, wondering how long it's been like that before I noticed, but pull over, check under the bonnet as you do for anything obvious, but nothing that I can see. Car doesn't seem any hotter than usual, top and bottom hoses both warm, coolant levels normal etc, car was driving fine, nothing out of the ordinary. Fan was not running but then I was driving like a vicar so not sure that it would have been?

So I give it ten minutes to cool down a bit, I'm only 2 miles from home, so start her up again and literally trundle home with no probs. Temp gauge went straight back to off the scale, even after a ten minute cool down, immediately after starting up again.

Get home, same thing, check again for anything obvious but nothing that I can see. Fan wasn't running at this point either but again, not sure if it needed to be?
Leave the car for about 4 hours, now totally cold, just flick the ignition back on and the temp gauge goes straight back to off the scale, cars not even running!

So what do you reckon? What should I check first do you think? How can I check that the fan is working correctly is my first thought?

And is it likely to be a faulty gauge or sender unit? As I don't actually know that the car is overheating, could be a faulty sensor perhaps?

And help greatly appreciated

Cheers,
DW.

 

Most likely the temp sensor gas shorted out internally, that'll make it go off the scale as soon as power is applied.

 

Agree with you , change the temp sensor and I bet it goes back to normal.

 

So I've been out today, started it up and the temp gauge went straight off the scale, ran the car idle for ten mins and the fan didn't come on at all either - so does the temp sensor control the gauge and the fan ?

 

Sender just does gauge as far as I can remember, if it's a sender with a black ring I'm pretty sure I have a new one buried down the shed

 

The temperature gauge is completely separate to the thermostat and cooling system control, what you see on the gauge in front of you is just a reading from it’s own brass sender, 99.9% it’s nothing to worry about, everything will be normal but the sender is giving a false reading.

Either the sender is bad, the wiring, or the actual gauge is broken, again 99.9% of the time it’s the wiring or the sender so very cheap fix.

 

Unplug the sender then turn the Ignition on, hopefully your needle doesn’t move, if it does that means the problem in the clocks or probably the wiring

 

As said by Luke, this will confirm the sender is the issue (more than likely).

The only thing I would say is be wary of the replacement you get, for many years now a number of them have are not scaled correctly, hence end up with a false reading.

Martin

 

Further to the above...If the needle does not move, touch the connector direct to the engine bloick - If the needle move up you'll know your guage is OK and this reeally does point to the sender. As far as getting a replacement sender - check trhe colour of your current sender near the connector and match this as different colours were used to indicate different temperature ranges,

Good Luck with sorting this issue
Cheers, John

 

Thanks chaps - so where about is the sender located please and I'll give this a go!

 

Right hand side of the head (i.e. turbo) at the front. This is 2WD, 4x4 may be different, just look for one wire around the head, if so.

Martin

 

Thanks Martin. Yes, mines a 4x4 - can't see anything obvious where you're saying to look so assume it's elsewhere on a 4x4? Anyone else any idea please? Cheers, DW.

 

Rear of the cylinder head, near to dipstick tube area on the passenger side.