temp gauge problems

[george roper]

I own a vectra 05 reg cdti sri 150bhp, the problem is
1) i don't no if i have a faulty temp gauge , the gauge works but if i drive my car the needle will rise to the first mark on the gauge, but if i stop at light's the needle will drop to the zero , then same again, the heater is working fine , when the engine has warmed up the heater is blowing hot air , but the gauge is showing zero if am stop at lights,
2) I have had a new temp sensor fitted ,because i was told this might be the problem, but no luck, been told might at to replace the clocks ,
the water level's are all fine. hope someone can sort this problem ,thanks

[cont1204]

Thats a bit extreme, could be a duff thermostat. Can be changed for a few quid. Much cheaper than new clocks!

[GazVXLINE170]

Thermostat. The hot air being blown into the cabin is drawing the hot air from the engine bay, and as the thermostat is jammed open (from your symptoms mines does the same), it will be cooling the engine down.

Whoever the mechanic was they should have spotted that or at least have eliminated it when diagnosing.

Gazza4

[chrisvectra]

you need a new thermostat fella as yours as stuck open

[1-8clusive]

I recently had to have a new thermostat fitted (Petrol 1.8) and saw similar symptons to yours, One thing to remember even when the gauge is on the bottom the water temperature could still be 70 deg C so your heater still works but not red-hot. Can you feel the hot air in the car get any cooler as it draws the heat out of the engine? If you can feel a difference in the hot air in the car that matches the temperature gauge it will help confirm it's the termostat sticking open. It's not a big difference though with mine the heater was really hot when engine is 90deg and just nice and warm when engine was 75 deg

[chrisvectra]

trust me fella its the thermostat

[myelite150]

[Tomb]

definitely

[Bigtee]

I own a vectra 05 reg cdti sri 150bhp, the problem is
1) i don't no if i have a faulty temp gauge , the gauge works but if i drive my car the needle will rise to the first mark on the gauge, but if i stop at light's the needle will drop to the zero , then same again, the heater is working fine , when the engine has warmed up the heater is blowing hot air , but the gauge is showing zero if am stop at lights,
2) I have had a new temp sensor fitted ,because i was told this might be the problem, but no luck, been told might at to replace the clocks ,
the water level's are all fine. hope someone can sort this problem ,thanks

The wire from the temp sensor put this to earth with ignition on does the gauge sweep over to the hot or does it fail like it does when you drive?

If it sweeps over and stays in hot the gauge is fine, if it judders it's faulty.

Same way as checking fuel gauge.

You may have a stuck thermostat but don't rule out the gauge for a simple test.

[george roper]

thanks very much for everyones help and comments, i am gonna change the thermostat i will let everybody know if it works , george roper