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MG MGF Technical - Temp Gauge

I've recently got back from a 2 week holiday and on my first journey the temp gauge shot straight to the top. I've checked the coolant level which appears to be fine, but the needle remains in the red.

Any Ideas?
Graham
Graham Elleray

Which year is the car, mk1, MY 2000, or a TF. You also do not say which temp gauge went through the roof, the oil temp or water temp. I'm pretty sure the people who know this stuff better than me will be asking for this info.
In the archives you can find something if you look for temperature or temp sensors.

Good luck, Johan
Johan Slagter

Does the temp gauge go up without starting the engine or does the engine have to run for some length of time?
John

Good questions guys.

Graham, either the engine really is that hot, or there is an electrical fault. If the gauge is shorting out, the needle would jump into the red practically as the ignition is switched on.

Sensor failures usually lead to the guages reading cold - unless it is the ECU water temperature sensor, in which case, the water temperature will increase in standing traffic and fall again in moving air (because the cooling fan(s) are not being triggered).
Rob Bell

being in the red is a bad thing, (ask any bank manager),
If the gauge is at fault then I would expect hot even before the engine was started.

If the Fan is not running (fuse, temp sensor to ECU) I would expect a normal heat up time, but in slow moving traffic the needle to creep up

If the water is low / there is an airlock / the water pump is not working I would expect the water temps to go up very quickly, but not the oil temps, but only with the engine running, I would also expect the radiator fan to spin up.

Only the last (few) is something to really worry about, esp. if the engine has overheated, get the garage to pressure test the system if you have overheated the engine.

Will
Will Munns

Graham,
I had a similar problem with the Oil temp gauge and oil temp warning light (VVC's only) which came on due to an electrical fault. Pressing the facia above the gauges caused the light to go off and the Gauge to read correctly.
Mike , M2 VJN, Trophy (Yellow).
Mike

Hi All,
Thanks for all of your help, after giving the car a bit of a run over the last couple of days it seems to have cured the problem (touch wood), although the needle does sit at 1/2 way when you turn the ignition but do not start the engine?

Cheers
Graham
Graham Elleray

You must have had an airlock in your coolant system..?
Hanah Kim

>>>although the needle does sit at 1/2 way when you turn the ignition but do not start the engine?<<<

If the engine is cold then there should be no deflection of the needle from it's stop until at least 2 to 3 minutes after start up, depending on ambient temp. If there is this half scale reading, say when turning on the ignition first thing in the morning there is definately a gauge/sender problem - probably sender.

Rog
Roger Parker

This thread was discussed between 30/10/2002 and 02/11/2002

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