the cooling fans on my car have started to switch on after even short runs..the temp gauge shows normal and the car runs fine..the water is up to the top as normal..when i stop the car all shuts down then the fans come on for about a min ot two..any clues?
still cool in the uk about 10 degs ..didnt have this last summer

 

Dennis,

The cooling fans in both my 2000 XJ8L and 2001 XK8 appeared to operate with little relation to ambient air temperature.

The control mechanism is the ECM from a signal sent by the temperature sensor (ECT) in the elbow next to the thermo tower. There's also a fan control module buried behind the front bumper which operates the fans in slow or fast modes.

I don't know the AC control mechanism but it must also have some input in determining whether the fans operate, at what speed and for how long.

Graham

 

If you have an obdII scanner, it would be good to check the actual coolant temp, than you will know if it is related to that or not. If it is (so high temp), it might be related to a sticking thermostat.

 

thanks avos, how easy or hard is it to replace the thermostat?

 

thanks ggg
think ill take the big hammer to this car.

 

A hammer! You must be a graduate of the Basil Fawlty school of car maintenance.

Do you run the AC all year round or leave it off during the Winter? Before you start thinking 'faulty component', it's worth getting the temperature up to normal and cycling max hot to min cold and back a couple of times to get thorough coolant circulation. One of the Stratstone Jaguar techs advised me to do that every 4 to 6 weeks with my XJ8L and I've just continued to do it.

If you do have to hammer some parts off, the ECT and fan control are straightforward. The thermostat isn't complicated:

JTIS - Thermostat - NA 26 45 07.pdf

Two things to look out for are not to get coolant on the drive belt or it will start to squeak (either cover it in a large plastic bag or remove it) and make sure the thermostat 'giggle pin' (the hole with the metal clip through) is at the top so any air can bleed.

Graham

 

i run my air con from time to time to make sure its stays in good condition
.
the info you sent is for a non s/c mine has s/c do you have a shortcut?
many thanks

 

Dennis,

Sorry -I looked at the chrome boot trim and thought 'Normally Aspirated'. Should have remembered your comment about this on another thread.

Here's the SC equivalent doc:

JTIS - Thermostat - SC 26 45 07.pdf

Same precautions apply.

Graham

 

The temp gauge will indicate normal up to 235-240 F ! Fans kick on at around 220 -225F. Stuck thermostat is a good possibility.

 

FLUSH THE RADIATOR and coolant system. Probably old junk gumming
up in there, i can promise you. Flush it with cleaner and then add new fluid after changing the thermostat and you will not have any more problems. Do it soon... the thermostat is going to stick closed soon and you are going to overheat.

 

waiting for themostat from british parts so will do it as soon as it arrives
thanks for reply

 

replaced thermostat saturday.car now seems ok..put the old one in a sauspan of boiling water the gave it heat. so it was bubbling..did not open binned it