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Temperature Light!!!

The Temperature gauge shoots up on my 146, after about 5 minutes of driving it reaches 130' and the red light goes on( it usually sits bang on 90')

I have check the expansion tank loads of clean fluid no oil mixing or anything, the fan kicks in and is working, the engine doesn't feel or smell hot and it runs completely fine.

Any idea what's wrong, faulty gauge maybe
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If everything seems normal you should check the sensor.
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Is thermostat opening as it should?
Check if the radiator and the hoses leading to it feel hot when temperature gauge is above 90 - if not then the thermostat is most probably staying closed, which would lead to the overheating you are seeing.
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1. air lock, next time turn on the heaters to FULL hot & see if heat comes out the vents.
2. wiring rubbing off the engine & shorting out the circuit
3. thermostat not opening [ unlikely ]
4. blocked cooling rad
5. failed water pump [ not a common failure but can occur ]
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Yes, I think you need to verify whether the "overheating" is real or not first... but in my experience those little sensors very rarely fail, so assume that there is a problem.

An air-lock is the least likely problem in itself since the system is self-purging. If hot air does not come out of the heater, then that might suggest a different air-lock problem - usually caused by the head gasket.

> To test for air in the system (when cold) loosen but don't entirely remove the air bleed screw on the back of the radiatore (by the r/h headlamp). Let any air out until coolant starts coming out.. That's the rad' bled. Don't take the screw right out.. or you'll never get it back in as coolant is ****ing out all over the place.. just loosen it a few turns until it hisses or ****es.

>> If there is pressurised air in the rad' that will stop coolant getting in there so this should solve the immediate symptom. Test the car again (cold) after a day or two and see if there is more air in the system. If you keep getting air in the system, that's a goosed head gasket. Nothing else.

A thermostat failure or a water pump failure would all cause your symptoms too. Thermostat is an easy test since the rad' will be cool while the hoses on the engine will be boiling hot. Change the 'stat and Roberto should be your mamma's brother.

Water pump is more tricky to diagnose since only a physical inspection will prove it for sure... which is a pump (and cam-belt) off job. How old is the water pump? They can run to 100,000 miles or more.. but if you definitely changed yours at the last cam-belt change for example, that would make it less likely to be the culprit.

The sensor could be at fault.. You could try getting a second-hand one and fitting it.. It'll just cost you a few quid and some coolant so if the other tests check out okay, then do this fairly soon (certainly before dismantling the water pump).

Ralf S.

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Well on further inspection, it is over heating - lucky for me it only just started to over heat so my mechanic thinks no damage has been done. He recons its a water pump failure, so its getting another new timing belt, water pump and gonna do the variator too. The belt is only on it 6K but its pointless not doing at the same time as the labor involved in replacing the water pump is much of a muchness.
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