Hello all ! Please help I have a problem with my XF s 3.0 diesel its overheating starts with engine temp high I have replaced the header tank the temp sensor and the thermostat and it's still doing it? Driving on a motorway it's totally fine but as soon as I sit in traffic for any length of time it starts to over heat the fans are running and if I put the heaters on in the car it drops the temp for the warnings to go off the car has done 150000 miles so I was wondering what to change or check next could it be the water pump as with the header tank cap off and rev the car the water doesn't drop???

Hope that makes sense to someone

 

Any codes in the system? That will help you diagnose issues. Otherwise it's just guesswork and could be pretty expensive

 

totally a stuck thermostat

 

If you've never changed the water pump that's where I'd start. If the impeller blades have worn down plastic (The blades just wear or break off), or metal (electrolysis will do and the water pump impeller is usually the sacrificial metal, if its metal), you're water pump is less efficient, and moves less water at idle so you get an over temp, hit freeway the water pump speed goes up, so even a broken water pump now works. The heater is just acting as a secondary radiator.

 

Before I start replacing parts, I'd make sure that there is no blockage of airflow to the radiator.
I'm not familiar with the 3.0 diesel. Does it have a belt driven fan? If so, is the belt and fan clutch in good shape?
Your symptoms, to me, are indicative of improper airflow through the radiator.

 

sorry for the late replys the car is still popping up with high engine temp an I have had the following work done - new t stat new temp sensor new water pump fan wiring checked and a broken connection sorted I have let a lot of air out the system and it was ok for 800 mile but now it's started to high temp again

any suggestions

thanks

jez

 

I had the same problem. Ended up being a faulty electric radiator fan. Check to see if it is working. Turn on the a/c and see if it kicks in,it should immediately. If it doesn't, you probably need to replace it.