Hi guy's,

I have finaly had enough of trying to figure out whats up with my jag.
its a 2002 xj8 sport 124000 miles with 3rd gen tensioners, was my daily driver for 2 year with no problems until I parked it up for 4 months over the winter.
when i came back to start it ,it just spun away without firing. I ended up changing the spark plugs (it was due new ones) and managed to get it fired up. brilliant!
then i got the knock sensor code p0327 and restricted performance, a new knock sensor sorted that problem. the old one had been bathing in a bath of coolant and looked just awful. I took the car for a spin down the road about 2 miles. when i parked back at my house i saw the temp gauge start to rapidly rise above normal and turned off the car and the cooling fan ran on hi for around 5 mins. I checked out the cooling system and discovered a leak on the manifold in front of the thermostat. I decided to change the manifold,water pump and thermostat for the aluminum housing and a new thermostat. all bought from British Parts

Cooling-Heating | Jaguar XJ8 X308 - XJR | British Parts UK

When i filled the system back up with a 50/50 coolant mix . i filled from the thermostat cap with the upper reservoir cap off. then filled the reservoir tank up to the fill point. I then followed the JTIS procedure for bleeding the coolant system.

I took it for a test drive and it ran fine and the temp gauge stayed bang on in the middle, i know the gauge is not an accurate reading to go by however everything seemed ok to me.

However now the cooling fan is getting me worried, when the engine is up to temperature at idle and i turn the car off the fan runs on hi for several minutes then cuts out. the fan will also run on Lo setting when the engine is at idle. The fan running on hi when i turn it off never used to happen and i dont want to take it out on the road incase it overheats again.

Hopfully there will be someone that can point me in the right direction.

Thanks

 

I think I would buy an OBDII reader that can read data in real time, including temp, IAT, short and long term fuel trim, plus lots more. Plug it in and keep it on while driving so to record temperature variants. the fan should come on at 203 - 205F or whenever the A/C compressor is on. So, you are either overheating or you have a bad sensor: can't tell without data.

Doesn't seem like the fans are bad, tho.

 

Thanks Jim,

I will give that a shot, I did have the a/c on a few times but i wouldnt have thought that would cause the fan to run on high for so long after shutdown.

thanks

 

Hi guys while I'm on here thought I would let you know that I discovered the cause of my overheating. Embarrassed to say it but I installed the thermostat the wrong way round.

Surely the aluminium housing would have been designed so it can't be put in the wrong way round but there you go a warning to anyone else, it is possible to put it the wrong way round