Every once in a blue moon my 2010 xk 70,000 miles when in traffic moving at a crawl for 20 mins or so I get engine overheating light so I pull over cool down 30 mins and it’s good happened about 3/4 times in last year always same conditions I’m in Florida so I know it’s hot , can anyone suggest what it might be I’m a green Jaquar owner but love the car had it for 4/5 years now .

 

Assuming that the coolant level stays full, I would suspect either a faulty temperature sender (which means the system is not actually overheating at all) or a faulty fan, fan controller or relay which means that the coolant is actually getting too hot.

If it never happens when the car is actually moving forward and air is being forced through the radiator, then I would favour a problem with the fan or its control system.

Richard

 

A dirty or bent-fin radiator or A/C condenser is a possibility. Also fan problems like Richard said.

 

it doesn’t happen when I’m moving quicker only in the turtle movement you think I should change fan

 

No. Part swapping is never the answer. Get an Infrared thermometer. Assuming you have no DTC codes thrown, you should be checking the temperature (point the thermometer at the hoses.) if the light comes on. Check to see if your fan is running when the problem occurs. $20 for the tool and your time is all it takes.

 

Thank you for yr honest answer I feel like the fan is not coming on you should be able to hear it correct , is there an auxiliary fan that should engage to help cool
it .

 

It does sound like a fan-related problem but, as Sean says, don't change the fan that will probably be a waste of time and money at this stage.

The easiest things to check first are the fan circuit fuse and the relay. The locations of both can easily be found online or in the manual. It's unlikely to be the fuse but it might have dirty or loose connections and it's easy to check. The relay is more likely and can be easily checked or buy a new one (they are not expensive) or swap it for one that operates the horn, or something else which is not critical, and see if that solves the problem.

If that does not solve the problem and you've checked the radiator is not blocked with leaves or something, then get the OBD codes read as if it is a fault with the fan controller or the fan itself, there might well be a fault code which will identify the problem before you start spending money on parts.

Richard

 

Get a digital coolant temperature gauge that plugs into the OBD2 socket. Once I reached 100 degrees C without any negative consequences. I think that is, 212 degrees F in your part of the world.

 

Easy enough to see if the fan is operational, get the car up to temp after a fast run. Stop, open the bonnet and see if the fan is running. Then check out the various thingies mentioned previously.

 

thermostat housing..

 

If you find that the fan is operational(when the overheating warning gauge warning appears the fans should be running continuously) it could be the thermostat housing has a piece broken off below the thermostat itself and found it's way to the housing above the coolant pump, this partially blocking the coolant flow hence overheating.
This part is called an outlet pipe and includes the temperature sensor and thermostat part no. AJ811793 available from SNG Barratt.
Paul

 

I just learned that the 4.2 L has two water pumps! A manual and an electric for the cabin heat. But without the second one working in some circumstance maybe the car could overheat. Does the 5.0L have the same setup?

 

Really? News to me. Now I gotta look at the service manual.

 

Only one I could find was - Auxiliary water pump (Intercoolercircuit)

Centrifugal type, 35w 12V DC electric motor

 

That's the only other one I know about. 4.2 and 5.0.

 

I may be wrong but did the OP mention that that his car was a 2010 XK, so not supercharged therefore no intercooler auxiliary pump fitted?

 

Mystery solved! The aux. coolant pump is only on the supercharged model. It was worth looking into.

 

The first suspect should be the thermostat and that it is not opening up completely. Change it and check the housing at the same time. Then test it in a pan of boiling water. Not mentioned is the idea that the water pump is slipping under its belt. So has this ever happened before? If you are caught in traffic and the overheat warning happens, beside pulling off to the side of the road and shutting down the engine, its OK to turn up the heat inside the car and open the windows. That helps a lot. I recommend this more than shutting down the engine. Coolant temperature sensors do malfunction and are inexpensive to change, for the do it yourselfers.

 

OK folks, help me figure this one out since the shop I took my car to didn't want to venture a guess since they couldn't replicate the problem and didn't see any codes. Like the OP, I too have run into the "high temp/ engine overheating" warning but also very very intermittently. I have an OBD app that I don't always have on, but I've made an effort recently to keep more track of temp readings. In the last 15k or so miles in Texas heat, I've encountered the high temp/overheating warning about 3 or 4 times. Always while sitting in slow traffic or putting along in the parking lot after driving without issue for a while. The precursor to the warning light coming on seems to be the AC suddenly not blowing cold air. The last time I got the warning light, I pulled over into a parking lot and my OBD app showed a temp of about 235-240 F. I can't remember if the fan was running or not. Is there a set temp when the fan is supposed to come on? Does it stay on even when the engine is off? After letting the car cool down for about 15 minutes, I started it back up, and temps went back down and stayed at around 199 F. Since then, I've been driving around with my OBD app connected and noticed that in pretty cool ambient temps (around 70 F these days), the engine temp fluctuates from about 195 to 208 F whether sitting in traffic or cruising at highway speed. Coolant level is consistent, and I replaced the water pump under warranty about 20k miles ago and preemptively replaced all the plastic pipes about 10k miles later. Before I run into the engine overheating warning again, what do you guys think could be causing the intermittent issue? I'm thinking of just preemptively replacing the thermostat housing with this new aluminum one: I figure it can't hurt, but is there a way to confirm if the problem is with the fan? Mine was changed several months ago in connection with a longstanding problem I've had with the AC in my car. Any insight you guys can share is appreciated since the local shop doesn't seem to have any ideas.

 

As mentioned above, I’d start with replacing the thermostat.