Overheating (Well i think so!)

[martins2]

Had my S for a few years now and in the last 6 months have not enjoyed being part of the experience.

Had problems with Fan not cutting in then car overheating. Checked fuses, checked connections everything from the bible! When I ran short of time even took it to Fernhurst had new otter switch fitted. Still no fan. So I have been running the car with the fan on all the time since then.

However recently the temp dial in the car has been reading normal running temp then leaping into the red before dropping almost immediately down again. Then repeating this for the rest of the journey. I am not losing any water and the fan is still running.

Strangely though, this doesn't happen when in traffic as when on the way to Goodwood this year it stayed at normal running temp.

I am loathed to keep driving the car in this condition just in case it all goes wrong.

Please help me before i lose it.......

[GreenV8S]

It sounds like a small number of relatively minor faults that shouldn't be hard to track down. Get an auto electrician to sort it properly if you don't fancy doing it yourself.

[s3swiss]

Given that you are not losing any water and your fan is permanently running, have you considered a faulty temp sensor or gauge?
On mine, the only time my gauge went in the red was when my fan sensor wires had come loose and the fan failed to cut in. The expansion tank filled up pretty quickly and steam vented from the overflow pipe as designed. If this hasn't happened to yours, perhaps it isn't actually overheating?

[honourablepickle]

sounds like the gauge is faulty
temp senders usually don't cause rapid changes of the needle
have you tried disconecting the fan and just letting it idle until the gauge just hits the red and measuring the temperature with a thermometer on the rad to see if it's accurate ?
as the otter switch and fan is independant of the guage there is no need to run it all the time just connect it up properly and let the motor come up to temperature (measured with something other than the guage ) and see if it cuts in at the right temp
if all is well with the fan/switch/gauge/sender then there is some problem with the cooling system - seems unlikly if it's not boiling or water isn't vanishing

reb

[F908 Tim]

My guage jumps about quite a bit and often goes up into the red before either dropping again very quickly,or if right at the top, coinsiding with the activation of the fan.(usually in traffic)
I am happy the engine is not actually getting to hot and I never loose a drop of water, so reckon its just the guage bobbing around.
Have fitted an override so if unhappy I swith the fan on, but suspect that when a mechanic lost a resistor once on my temp sender switch circuit,he simply replaced it with the wrong one.
Suspect yours is OK too...as long as no other symptoms like steam appear.

[Pies]

If you think about it its not possible for the water to change temp as quick as your saying,i'll suspect its an electrical problem

[martins2]

Thanks all for your help. Does anyone know where can i get an overide switch from? and at what cost?

[F908 Tim]

Halfords,partco or whoever is near you.

Mine is just an illuminated on/off rocker switch I mounted on the side of the centre console.
Wiring is straightforward and shown in a diagram in 'The Bible'.

Worth the peace of mind!