First warmer day here in the NE, 80 sunny no humidity. I was parked for ~15 minutes, AC on and the high engine temp high warning light came on. I turned the ignition off, cooling fans are working and continued for a few minutes afterwards. Restarted after ~15 minutes, no warning light. Drove to my shop guys close by, replicated what happened and the same thing occurred. Checked coolant, just below minimum level but the low coolant warning did not proceed engine temp high warning. Thoughts? Temp gauge? Water pump? Thanks!

 

The first thing I'd do is check for leaks. Have your mechanic refill the radiator and do a cooling system pressure test.

 

I wasn’t very clear regarding the current anti-freeze fluid level. The minimum level of which I was speaking is that of the overflow plastic bottle/tank, it’s near the top with fluid, I will not have to add much at all to get to ‘full’. Not sure if that changes the situation.

 

There is no 'low coolant ' message on the 4.2 models.

I agree with Stuart on the advise. You can also plug in a scanner and compare the temp from the scanner with a temp gun. Just to make sure its actually running hot.

 

There is a good chance that the theme stat or its assembly is failing. If it’s the original it’s very likely.
Very common problem and can stop the actual stat from opening fully .

An inch below the correct water level is unlikely to cause overheating

 

If your car overheats and the engine temperature warning light comes on (assuming you haven't lost coolant from a burst radiator hose), switch your AC off and turn your heater on to maximum heat and the fastest fan speed. Your heater is a small radiator, and the flow of coolant through it can help bring the temperature down. This is useful if you can't immediately pull over to stop and turn off the engine and open the hood (bonnet) to let it cool down.

 

Well that’s good to know re low coolant message! I was going by a discussion with the shop where I purchased the car since they sells XK’s almost exclusively. I will proceed as you and Stu advise!

 

Thank you!

 

Yes thermostat is a good thing to look at too!

 

That's what the button at the bottom right corner is for. 🙂

 

Out of curiosity what the temperatures should I be seeing on my OBD scanner during normal driving conditions? Today is one of the first warm days i’ve driven my XK and I was seeing between 212 and 217f And was getting worried there might be an issue

 

Those sound like normal temperatures👍

 

that’s a relief to hear, I had a crack in my expansion tank and it overheated and left me stranded. Since then I have been paranoid about it happening again

 

Thermostat is an easy DIY check using an infrared thermometer for $20. Check temp using the IR before starting the engine, then Start the engine cold, point the laser at coolant line on either side of the stat. One side will heat up and once it opens, the other side will match. If memory serves the stat starts opening @ 176 degrees F and is fully open @ 205.
You can also do a half *** check using the same method on the water pump inlets and outlets. It's not fool proof but it steers you in the right direction.

 

Lets start with, correct the level of the fluid. You may have an air pocket in the system.
Fluid does expand and contract with temperature changes. But to be below min is not good.
While on that, when is the last time you had a fluid flush? Coolant abilities deteriorate over time... and assuming you are using the right fluid and not some cheaper alternative as capabilities vary drastically. Let alone if different fluids are mixed.

No spots on the ground under the car? No odours? No obvious tell tale signs of leaks on the hoses?
It is an 07, and at 70k continual routine maintenance is paramount.

 

For my situation (thread starter), I just ordered Peak Pink which to my knowledge is the recommended fluid, picking up later today. There are no leaks / spots, clean. I have only had this car for a couple of months and while it only has 58K miles, I don’t have detailed records. The interior, exterior and mechanicals appear sound, no rust, etc. That said, I have no issue proactively replacing the thermostat and water pump given I have no clue when or if they were done. I did both on my VW Rabbit prior to selling so the new owner had ‘fresh parts’.

 

Like someone else said above, change all the fluid you can for new stuff! Yours may be very old and crappy.

 

So, ordered a thermostat + housing and water pump (Gates - metal impeller & gasket), 2 other water pumps I looked at had composite impellers which my shop guys were not fond of. I read pluses and minuses on both but elected to go with the metal impeller. Regarding the thermostat, good thing I ordered the thermostat + housing, my guys said the existing housing was installed improperly with an incorrect bolt and was challenging to remove, i.e., was likely mangled upon removal. I ordered the housing in the first place because from what I had researched, they have a tendency to wear out over time.

Got the car back Thursday and have had no “engine heat high” light come on and today I drove about 40+ miles in 94 degree weather, AC blowing, no issue. As a final note, before the work was done, I noted that my cooling fans were coming on often. Today, even with the hot temps, didn’t hear them at all. Thanks for all the help!

 

Are there any high coolant temperature warning lights for 4.2 XK’s?

Currently I have been using Veepeake WiFi OBD with Autometer DashCommand app on my iPhone to monitor coolant temp occasionally.

My 2007 XK 4.2 now has 170k plus miles on it.

Way back around 80k miles had to buy a new electric cooling fan, thermostat housing and thermostat, replaced idlers and belt back when the mileage was less than 80k miles. Eventually got overflow tank crack addressed, new tank, and one of the heater hoses over the alternator failed at warp speed in a curve, almost lost control when it sprayed the RF and RR wheel while getting on it in a curve in the road. That hose was fun to replace FYI.

All that being said,

Now it has a leaking radiator and the Behr units run around $700. How come an XJ or XF radiator can be had from the aftermarket makes like CSF for around $100-$150 but not the XK? You would think an XJ or XF radiator from NA models of those types would be similar.

Sure would be nice to spend $700 on a radiator that’s gonna last, but we all know these parts aren’t gonna last. Dreaming of an aftermarket solution that’s either cheap like a CSF radiator or an all metal radiator that is worth $700 plus. Driving my 1995 Range Rover and not saving gas until I can find a radiator. Any ideas or creative mods to an XJ or XF radiator are welcome if anyone knows any, I am all ears. Miss driving my DAILY DRIVER XK.
🐍
2007 XK 4.2 NA
170k plus miles

 

Yes, post #1 shows the warning. As for your radiator issues, I've never looked into it so I can't comment.