Recently I've had the engine fan continue to operate at high level after I've parked the car and shut down the engine.
The other day I noticed the temperature gauge rising relatively fast so I went home and parked the car. I've looked around the forum and I suspect it could be the thermostat.
As a test today I topped up the coolant and started the car up. There was a high pitch noise from some belt when the engine is cold but otherwise everything seemed fine. The engine fan did not turn on right away. I took her for a spin and drove around the neighborhood for about 20 minutes while watching the temperature. All seemed ok for most of the time. Then I noticed the temp gauge move up from around mid level to a bit higher quite quickly. I decided to head home. As I pulled into the garage, I was reaching the upper levels and as I parked the car and shut off the engine I even got the red warning light turn on. (First time I've seen that). Again the engine fan was on high blast even after turning off the engine.
Any advice much appreciated!

 

Thermostat, water pump or head gasket(s). By the way, Jaguar advises that the thermostat should be replaced every two years.

 

Thanks for that. I'll order a new thermostat to begin with.

 

Ok I got the new thermostat. When I tried to replace the old one I used the 8mm wrench from car to try to undo the bolts on thermostat housing. The bolts are very tightly done and I couldn't undo them. I even slipped a couple of times and I'm concerned it's getting worn.
Any advice on how to undo them? Picture attached.

 

Heat the aluminium around the bolt with a small torch (a pen torch will do) and try the bolt while hot. If no go, let it cool down and try the bolt again. If still no go, heat again, try the bolt etc. Use a six point socket for this or, at least, a ring spanner (don't even think about using a simple fork spanner for this, even if the bolt is not seized or overtightened). Hopefully, as the aluminium expands more than steel, the bolt will loosen after the first heat-up. If not, then the heat-cool cycles will hopefully get it to move. You can also try spraying a bit of penetrant on the bolt flange and at the back.

 

Thanks for your help!
I was able to undo the thermostat cover bolts using your technique.
I cannot remove the old thermostat from the housing though. I tried pulling with a pair of pliers. Any advice on how to remove it safely?
Picture attached
Also I have a new thermostat that I ordered the other day (Gates EBC3621).
This one doesn't have the same air bleed valve (brass with ball bearing) at the top like the old one. It has something similar on the inner part though. How should the new one be positioned when installed?
Picture attached

Old thermostat

New thermostat

 

It is just stuck a bit. Use a suitable wood stick placed on the "U" of the thermostat and (not too hard) knock with a small hammer repeatedly until it loosens. The air bleed hole of the new thermostat should also be at the top.

 

Thanks again for your help.
That worked. I replaced the thermostat and tightened up the bolts. Obviously a bit of coolant was lost during the process. I filled up some more. I turned on the engine and everything seemed fine. Not even any squeaky noice from the belts.
However I moved the car around a bit in the garage and gave it a quick wash. Then I noticed a large pool of coolant under the front of the engine. At closer look it seems to be leaking quite aggressively when the engine is running.
I cannot see any leak from the thermostat housing area though. Any advice again?
Picture attached.

At closer inspection it looks like it is coming from the lower part of the engine area.

 

With the engine off, use a small mirror to look just under the water pump pulley. But you’ll eventually need to run the engine again to verify where it’s coming from.

 

Yes, looks like it is the water pump next.

 

Oh ok thank you. Where is this located? Does anyone have a picture or description of how it looks?
In general, is this a difficult job to fix?

 

The water pump is just below the thermostat housing. I have attached extract from the Workshop Manual.

You don't need to remove the two bigger bolts marked by the red lines, just the other 5 smaller bolts.

 

Thank you very much!
This looks like a bit of a bigger job.
I'm not really an expert mechanic. Is this a type of job you recommend to more of a professional?

 

It is not too difficult but it cannot be done with the tools from the Jaguar tool kit. You would need a 1/4 inch ratchet, sockets and extension bits. Also, the surfaces where the pump gasket sits on the engine block would need to be inspected and cleaned. The 5 bolts that attach the pump are small (M6) and care should be taken not to overtighten them - better to use a torque wrench.

 

Ok understood much appreciated.
Should I buy a new water pump?
I can buy new water pump here in Japan quite easily. I found a GMB one for around $100 equivalent.

 

GMB pumps are ~$35 on Ebay (appear to be cheapest). Seems GMB have two types - with plastic and with metal impeller. Plastic should be GMB 125-6030 and metal GMB 125-6030A. Most people prefer to go for water pump with metal impeller.

GMB plastic:


GMB metal: