Took the car to a local track last weekend for open lapping, lots of laps, lots of smiles, lots of tail wagging. Quite a small technical track and the Jag clearly had way more power and weight then needed. Still...lots of fun was had.

About 9 laps in or so 'High Engine Temp' in yellow flash on the dash. Not completely unexpected but I noted the engine temp gauge never moved up past mid. I did a cooldown lap then went hammering it again. Next session out I eventually also got the message again, also noted temp gauge was solidly in the middle and gave appropriate cooldown lap as before.

Fast forward to Tuesday and I was driving down a local highway in manual mode between 3-4krpm for about 10 minutes and I again got high Engine Temp Warning. This was unexpected as it was 17 degrees out that morning and I had hammered this car everywhere until then and had not seen this warning on the street. I again noted the temp gauge remained dead centre. So now my concern was; is my motor really running very hot and I'm not getting an accurate reading? Or is my sensor just giving up the ghost.

Called my indie tech at lunch and got an appointment to bring it in the next day. While driving it to the shop I also got a CEL. This wasn't completely unexpected as I had an on/off CEL for 2 weeks or so prior, some modules in the car were not happy.

Tech calls me later and advises the CEL was a engine temp sensor malfunction and the engine appeared just fine (whew). There are 2 temp sensors and the replacement kit also includes a small valve/hose. Perfect let's get it swapped out. I'm still waiting to get the car back (more on that in a bit), but hopefully this solves this situation.

So just a explanation to those that may run into this in the future.

As for a related story with the track. The tech also did a one over to see if I managed to break anything at the track and apparently I did! He noted the drivers side CV boot was melted and front axle appeared to be damaged. Recommended replacement before any long trips (I'm back to the US end of this month for some back road shenanigans). Will replace both.

I am currently running new front brakes; R1 concept drilled and slotted discs and Porterfield RS4 brake pads as I recall. The heat coming off these after a track session was immense. In fact it popped both my Vossen centre caps off my wheels as the plastic had warped!!

Happy lapping!

 

A little more history on this?
Jaguar has for years "damped" the temperature gauge response. We really have a temperature indicator and NOT a gauge as it will keep the needle exactly mid gauge under a wide range of temperatures. So it's not uncommon to over heat your engine and the dash gauge to never move off center until it's too late. Some of us run after market devices to read the actual coolant temperatures. I use and recommend Torque Pro.

Very glad to hear it was a sensor problem too and not the engine over heating. Good that the CV axle stayed together until your mechanic found it.
You were running hard!
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Yes agree. Jaguar has been doing this with coolant temp gauges all the way back to at least my 1996 Vanden Plas (that I remember). Might have even been that was on my 86 S3, but can't remember that.

The dash temp gauge settles at the half way point and pretty much stays there regardless of what the actual coolant temps is. Makes this gauge useless for all practical purposes. Still that way in my wife's F-Pace.

 

Your right I think it was a 1990's Jaguar that the guy did the testing on. That was the first time I had read about it. So it's been that way for a long time.
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Good to know! Appreciate the responses.

 

I always monitor the coolant temperature with the Torque app. The Car temperature gauge pointer reads in the middle at about 165 F and will stay there up until 212 F from what i have seen so far.

 

Wow, that’s crazy if true?!?!

It literally is basically pointless to have the temp gauge if it truly behaves the way you guys are saying. Wow, I can’t believe this.

So dumb

 

Will it at least proactively give this “running too hot” message being talked about even if the gauge itself is supposedly useless?

 

+1 on the Torque app. I never drive the car without knowing the realtime temp of both coolant and engine oil displayed in the Torque app on my external device. The coolant temperature gauge on my dash (2015 R) is just useless until it’s too late.

 

The reason I have read for damping the gauge response was the temperature gauge would move as the engine changed temperatures (Like it's suppose to!) but the "typical" Jaguar owner in years past would panic if the needle moved at all off the center position and run to the dealer for repairs under warranty. It got so bad for Jaguar and so expensive that they did this to reduce those useless and costly dealer visits when there was nothing wrong with the car.

Now is all this true or just an urban legend? Can't say but if you investigate it at all you will soon find that dash gauge is pretty much useless as posted above.
Does anyone know which cars have this High Engine Temp Warning? My car has so far not over heated on me but I don't know if my 2014 XJ even has this?
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Yes, I've heard this same story about customers worrying about the gauge moving. It could be true. I go WAAAYYY back on this forum under a different name and I know that story was WAAAYYY back in the old days.

 

Probably specified in the manual.

 

Well,

Sadly the temp sensors replacement did not fix the problem. Picked the car up and 30 mins of harder driving later, warning came back. Day after I was accelerating hard on the hwy and it came up again, this time I also noted the engine coolant icon went from white to red. I went to pull over but both warnings had already gone away. Checked my engine bay after and I can see what looks like coolant splatter on some hoses/coolant reservoir.

Going to monitor temps with an OBD2 scanner and bring it back to the tech next week.

 

Got Torque Pro app working and drove home from work yesterday, manual 3rd gear run up the highway at a constant 3.5k-4k revs for 5 minutes. Temp went up to 119 C!!
Put transmission back in auto and did the speed limit, about 5 minutes later coolant temp crept up to 121 C!! Got Engine High Temperature warning followed immediately by Engine Over Heating in red. Immediately pulled over and was ready to kill the motor but the temps dropped immediately back down to 96 C. Made it home with constant temp of 97-109 C.

Parked until I can tow it to the techs, So the story continues!

 

@Evoex Blacklight the engine bay in the dark and you will find your coolant leak.

 

Yeah I believe i noticed coolant splatter, took some pics and let the tech know.

 

Sorry to hear you’ve still got issues.
I think the max I’ve gotten mine to is 106 C. Good to know the system can go well above that temp before hitting the engine overheating message.

 

Tech does not believe it is air pressure in the system based on the tool they use to purge it during coolant install.
Does not believe it's a leak as this was checked prior to installing the replacement engine heat sensors..and i was having this issue prior to that. Coolant splatter is result of sensor work as there was a hose/valve install needed with coolant at that time.
Combustion test was good.

At this time stuck thermostat is believed to be the culprit, ordered a new one and water pump. Sadly i already replaced these in March as preventative maintenance, from EuroAMP.

 

All jags have a temp gauge that goes directly to normal temp within 2-3 minutes regardless if the car is up to temp or not, gauge will only move higher when certain conditions are met and is controlled by the engine computer. Many, many people have ruined an engine because of this feature, including your truly going up a steep bridge in my XK8. I would say 113C would be a normal temp in traffic or at high speeds, but 121 is way to high.
1) How many miles and what is the coolant level?
2) Have you ever changed the coolant?
3) Coolant splatter could be boil over and the car does this to relieve pressure so it doesn't bust a hose or plastic pipe.
4) check for weeping around the water pump?

Anyway, good luck with your car!

 

1) 83,000km - coolant level is near full
2) yes - when preventative maint. was done back in March of this year - aluminum piping, water pump & thermo..as well as belts, SC work, etc.
3) my suspicion as well
4) it was all inspected a week ago when i had the sensors replaced