Hi guys

I need some help please.

I have a 4.2 Supercharged 2005 model.

My temperature gauge is "erratic". When driving round town it will sit nicely on the halfway point. However once I get a run of 50 mph or more, it quickly drops to the quarter line (or below). My air con also seems to be affected by this as I lose cold air when it drops.

Does anybody have any idea what this might be?

Sounds like you need a new thermostat (or one of the many that there are) would start with the main one though. IIRC, you are lucky and this is an electrical one and sits nicely at the top of the engine at the front on petrol models. .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Great - I did wonder if that is what was needed.

I have tried to search for a method/video to change it on the 4.2 Supercharged Jag engine but cannot find one.

Will have a look at the Jag forum I guess

Have ordered a new thermostat and gasket from Dan at Duckworths.

Just need to find out how to change it now!

Just be careful sir, the 4.2 can be a challenge to bleed at the best of times

Now I am worried.
Might takes it to my local garage!

Ok I am getting the courage to have a go at this.

Do you guys think this is a DIY job?
Any guides available as I cannot see them online anywhere for the Supercharged 4.2

Slightly concerned that it is a bigger job than expected?

Isn't it going to be the same as a Jag XJR? Lots of guides for that.

I didnt think of that!

Will google around to see.

Thanks

Pretty easy if I remember rightly, as you look in the engine bay from the front its kindof to the right of the centre of the engine at the front. Look for a big metal tube connected to rubber water hoses about the same size and shape as the new thermostat you will get.

same year as mine easy job took about half hour on mine . Think it was some american bloke i watched doing it step by step online v good will try and find it