Hello Everyone! I'm new to the site, and am pleased to be a member of the forum. I've owned my 2001 XJ Sovereign since Feb 09 and have enjoyed every moment of driving it since then.

I've just returned from a week of driving round France in my XJ and enjoyed it, however my XJ developed a problem on this trip. I noticed the Temp gauge had crept up to the top of the red, and the warning light was on. I instantly switched off the A/C and the gauge returned to normal quickly. I initally thought it was because it was quite warm outside and I was working my way up a long hill which may have caused the heat up.

However whilst driving on the motorways the gauge crept up again, and I repeated the above again. I felt sorry for my Girlfriend who had to endure the heat of HI being blown into the cabin whilst all 4 windows were opened on a French Autoroute from Rouen to Calais. Luckilly I made it back home today, and the regular checks I gave the XJ's fluids and key engine parts threw up no clues as to what the issue could be.

I suspect it could be the Thermostat, or the water pump. I hope it's not the latter. Does anyone know the location of the Thermostat on a 01 4.0 V8? And the replacement process? Thanks for your help. Stu.

 

Hello Stu,
I guess I have the U.S. equivalent of your car, it's a 2001 Vanden Plas. I replaced the thermostat and the water pump a couple of months after I got the car.
There are examples of either of the two failing and causing serious damage to the
engine, so I would do them both, and it's easier to do them both at once. The original
water pumps had a plastic impellor - which has been known to fail and shed pieces
through the cooling system. The themostats apparently don't last long either. The
good news is it's a relatively easy job to replace both. Just about all you need is an
8 mm socket. The thermostat is under the plastic thermostat housing meets the
block. Drain some or all of the coolant first, and make sure to get the right kind to
replace it, mine uses OAT - organic acid technology and it's orange. Then slacken
and take the serpentine belt off the pulleys. Then as I recall, it's just unbolt the
parts and take them off. No gasket sealer required, everything has rubber o-rings.
Remember the thermostat housing is plastic - need I say more ? A good place for
repair and maintenance info is Alldata.com. You need to subscribe to it for your
car, but it's not real expensive, and it comes in handy. (~20 USD for the first year,
slightly less after that)

 

Does anyone know if the 2002/3 XJ8's still have the water pumps with plastic impellers?

 

Thanks for your advice! I was pleased to see someone replied to me! I'm going with the thermostat to begin with, but I'm trusting the work to my mechanic. I don't have too much time to play around with the car and I'm a bit afraid to play with the cooling system itself. I'm not too sure about bleeding the system afterwards either.

I have done a few other jobs on my XJ though, I changed the spark plugs to Bosch as I don't like NGK plugs. Also I'll be doing an oil change after I've got it home from the garage.

Thanks for your advice! Stu.