Temp gauge goes crazy!

[freedriver]

This arvo on my way home I got a bit of a shock when I looked down at the temp gauge and instead of being in the normal horizontal position it was way down near the cold mark. I have seen this before on another car when out dropped a radiator house, but the mad man gauge was reading 88 and the coolant level alarm was silent.

So is this a sign of some problem with the thermostat?

Has any one here had this happen to them before?

The vehicle is a 2002 td5 disco with 145k km on it, any thoughts would be great. Cheers Bill.

[simonmelb]

Hi Bill

Yes, this just happened to my TD5. It turned out to be the wiring that goes to the coolant temp sensor shorting out. Check the wiring where it goes in front of the engine. You should be able to see it inside some convoluted conduit and held by a clamp. This is where mine wore through (ie inside the clamp just above the EGR exhaust cooler).

If this is OK, then your sensor could be faulty (you can test this with a multimeter, measuring the resistance at various temps). Or if the engine is not actually getting up to temp then it will most likely be a faulty thermostat, which you could remove and also test.

[freedriver]

Thanks, you may well be right. I found that when I fitted the mad man sensor it makes the original sensor move out about an inch so the wiring contacts the engine cover and I think this caused the gauge to go wild.
I trimmed up the cover with dremel and now it seems to be back to normal. It made my heart jump when I saw the temp gauge dowm do low ,i hope the engine saver will let me know if I ever drop the coolant.
Can someone tell me a easy to test if the low coolant alarm is working?
Cheers,Bill

[Sully]

Can someone tell me a easy to test if the low coolant alarm is working?
Cheers,Bill

It should self test with a short beep every time you start the car.... But... If you want to do a real test on it, remove the sensor from the coolant pipe/where it's mounted, swith the car to the "ON" position on the ignition barrel (don't start it as you'll lose coolant) and the alarm should constantly beep due to there being no coolant present.

Reassemble, start to seft test the system to make sure it's all back to normal and away you go.

[freedriver]

Thanks Sully. I thought that would be the way to test it and it seems mine is not working. Better to find out now i guess than after .

[greendisco2]

hey bill , yeah i had this happen about a month ago heading for raymond island the temp gauge just dropped pulled of the freeway let it cool down check top tank alright wait 15 min start car temp goes back to normal drive on no probs for the rest the of weekend sprayed with contact cleaner when i got home seemed to be a lot of oily s#@t come out of the plug no probs sincetony

[Sully]

Thanks Sully. I thought that would be the way to test it and it seems mine is not working. Better to find out now i guess than after .

Trace the wiring for the entire unit to make sure it's still all connected properly. Might be a simple case of loose connections?

[freedriver]

Ok I'll have alook at the wiring . It is quite new so maybe it has chafed through or something