garage says gauge........

[andymadmak]

Bit of a mystery this one. Friend of mine has a 1996 214 16v (bubble).
It had a new radiator over the summer when a local garage diagnosed that a VERY occasional
(only happened twice, 6 months apart) overheating was due to a knackered rad.
Since then no problems, until this past month.
Symptons are occasional coolant loss (no apparent leaks anywhere) of about half a litre of coolant, plus very erratic temperature readings.
There is absolutely no sign of HGF on the external parts of the engine. There is no sign of oil in the coolant, or coolant in the oil. No mayo, no scum, no nothing. Engine starts and runs fine, pulls like a train, compression is good.
This morning temp went off the top of the scale, then the needle rapidly went to normal, then back up to mid hot (above normal) then maxed out again, then normal, then maxed - all very quickly, more like a rev counter than a temp guage!
I suggested it may be the thermostat, or HGF. garage said HGF, then phoned to say HG OK, but gauge was faulty. OK, so I can see all the sypmtoms to suggest the gauge may be faulty, but equally, how common is this - and is the coolant loss just a coincidence?

Any ideas?

Andy

[Dave 500]

More likley to be the sender sould only be a 5 min job to change and only cost a few quid. I would try that first

[Tubb]

If the temp gauge needle is moving all over the place then i would suspect there's air in the cooling system.

Try bleeding the system and see if it makes any difference.

[Towie]

If it`s that quick it`s unlikely to e be related to the temp of the water. I would suggest an electrical fault. Is it a one or two wire sensor? Does the car start ok? Is the earth strap ok?

[scooterscot]

Change the filler pressure cap as they are known to have a short life, the cap lifts and lets the water evaporate. The lack of pressure allows the water to boil at a lower temp than if it was under pressure, when the level drops you get air in the system which shows up as temp rise. We change the caps as part of the yearly service cycle to deal with the problem.

[jimtyjimjim]

change filler cap bleed the water sytem change the temp sencer if none that works try the 1way vavle on the back side of the head by the injectors small thin pipe that go,s on back of head it sometimes get stuck with sh,t and don,t allow the water round the engin causein over heating