Hi, 2.5 Petrol AWD X Type new owner.

The car was sold to me as overheating, I knew enough about common issues to diagnose a faulty fan control module so replaced that, the water pump and thermostat which was all done on the driveway in half a day. Fan control module sorted the problem, the other two parts were just worth doing at the time as they were cheap and easy.

That work has fixed the car to a point where I’ve now done 450 miles, four 75 mile drives on the motorway, monitoring the temp via the ODB2 and an iPhone app.

Thought I’d ask here for advice as there’s still a little issue. If I don’t let the car fully cool down, when I start it up again the temp climbs above 84 degrees (thermo is rated at 82) and sat at lights or in slow moving city traffic it’ll head towards 86, and when I get home the brakes and front alloys are red hot. As soon as the car hits 30mph the temp on the app drops down to 83 and stays there, again climbing if I get to traffic lights.

What’s happening is the fans cut off pretty much the second I turn the car off, so if parked for even just five minutes the temp rises as it’s parked up, with no cooling.

Im assuming the fans should keep on spinning for a while and wonder what advice you can give me. I’ve ordered a new sensor to arrive and be fitted tomorrow, but is there something I’m missing? Coolant is the right type, and looked good on purchase, and when drained to fit the parts no sediment came out. Burped the system several times and topped up after fitting the parts.

Fortunately this is a bit of a ‘luxury purchase’ to be used on runs where we drive up to 100 miles, park up for the day or overnight, and then drive home when it’s cooled but it would be great to get the coolant system running perfectly and the car deserves it, there’s zero rust, engine bay is incredibly clean, exhaust looks pretty new. There’s only 76k on the clock and while it came with zero service history (only cost £600) I like the idea of keeping this for years to come and only putting about 2000 miles on it per year.

 

Is the fan control module original Jag? The fans should stay on after the car is turned off which would help significantly with your temps rising immediately at start-up. Are the fans and shroud original or did someone mess with that when they had the overheat problem? Original fan shroud seals pretty well to the radiator and the fans have a tight tolerance to the shroud. Aftermarket parts often get these details wrong which results in recirculation, i.e. the hot air out of the fan gets sucked back into the low pressure air in front of the fan. The fans are then moving the same hot air around and not pulling as much cool air from in front of the car. It only shows up as higher temps at idle and stop and go traffic.

You might be too conservative worrying about coolant temps in the mid 80s. The system is designed to keep the temperature around 90 because the engine operates more efficiently at that temperature.

The brakes & wheels heating up seems like the bigger problem to me. If you boil that brake fluid you'll have an exciting time trying to pump the pedal to get any braking. Sounds like dragging calipers is most likely although I had a similar issue after doing some brake work and it turned out to be the rod that the pedal actuates somehow went out of adjustment. With some help here in this forum I managed to find the adjustment and I have had zero brake problems in the years since.