I have a 2004 s type diesel sport. twice in the last year the temp gauge has gone almost into the red the two occasions I was in standing traffic one in summer the other winter luckily on both occasions the traffic started to move and the temp dropped to normal. since then iv got the car to temp at home and left the engine running to try simulate standing traffic.i did this for 45min the temp stayed normal on the half way point please advise

 

You're right to be concerned about any Jaguar overheating - it's an engine killer.

Provided there's no accompanying coolant loss, the regular favourite culprit is the Thermostat sticking followed by the Water Pump.

When you get a minute, please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST section and post some info about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice on posting to the forum.

Graham

 

I agree it could be the thermostat but the header tank has hot coolant inside I would have thought if thr thermostat was not working I would have no flow to the header tank.could it be the radiator fan switch

 

The coolant flow is as follows:

1. when the engine is cold and the thermostat is closed, coolant flows from the water pump through the engine. It then returns to the water pump through the upper coolant hose.

2. when the engine is warm and the thermostat is open, coolant flows into the radiator through the upper coolant hose. It then returns to the water pump from the radiator through the lower coolant hose and engine oil cooler.

3. a pressurized coolant expansion tank system is used which continuously separates the air from the cooling system and replenishes the system through the coolant expansion tank outlet hose, attached to the heater return hose.

4. a continuous vent from the engine and radiator to the coolant expansion tank prevents air locks from forming in the cooling system.

The coolant in the header tank will heat up with or without the thermostat open. A thermostat can fail completely closed but more often sticks partly open, restricting the flow.

This doesn't discount a non-operational radiator fan switch as a contributor or cause of the overheating.

Graham

 

thanks for reply when iv left the car running for almost an hour the temp stayed normal gut at no point could I see the fan running as this temp problem had only happen twice in 18 months im at a loss to if I have a problem.would I get a red or amber warning light in the fault message list to warn of overheating

 

would it be fair to say if the header tank is getting hot coolant the water pump is working even if thermostat is not

 

Yes - that has to be a reasonable assumption. Coolant must be circulating for the temperature in the Header Tank to rise noticeably.

Graham

 

any faults with the 3ltr xf diesel jag

 

Are you considering a change from the S-Type?

If so, the XF and XFR ( X250 ) - Jaguar Forums - Jaguar Enthusiasts Forum section is the best place for information on X250 issues or reliability.

Graham

 

hi iv had my fan tested and its working but still the fan is not getting a signal to start iv been told there is no fan switch on the radiator on this model