I will start by saying that my 08 4.2 NA engine typical working temperature seems to me too hot

No water leaks, new hoses, thermostat housing is 2014 dated looking good, radiator fan working

So I installed OBD reader to monitor the temp

Usually it takes quite a long time for the engine to warm up so the thermostat definitely is able to close

Daily driving, I see about 92C (197F) but would go up in traffic up to 97C (207F). That seems too high to me.

Yesterday during an extremely hot day 38C (100F) and hills climbing I got up to 105C (221F) at revs below 3K which really scared me off. That seems extremely high to me!

I know yellow warning is at 118C (244F), which looks to me crazy hot BTW, so following the book I shouldn't be alerted yet

However, I am used to see in other cars a steady 89-92 C (192-198F) and being relatively new to Jag I am not sure if need to worry or these ARE typical temperature for the X150 4.2?

Is my cooling system working well?

Should I suspect thermostat, radiator other?

 

I have a variant of your engine and that sounds OK. It worried me too until I investigated why - it's more efficient.

The dash indication is next to useless, especially in the case of an imminent overheat, so some people keep an eye via OBD as you have. Check your OBD tool does not flatten the battery.

 

Thanks for taking that investigation...
So what would be the "normal" temperatures to be seen on the OBD ?
When should I be starting to be alert ?

P.S. The OBD tool shuts off within short time after engine shut off

 

I have the same NA 4.2 engine. The thermostat was replaced 1 year ago, along with the coolant temp sensor, but hoses, radiator etc should be untouched on my car.

I've set Torque to log a number of variables once per second, and have logs spanning nearly 2 years by now. I only have data back to 2018-10 with me at the moment, but the highest engine temperature I've got there is 97°C...and that has occurred only once.

I have the following number of data points for temperatures over 87°C:
97°C: 1
96°C: 78
95°C: 3507
94°C: 5725
93°C: 29140
92°C: 64083
91°C: 172245
90°C: 226732
89°C: 29613
88°C: 33133

Generally in my experience it drops below 90°C at highway speeds, while idling in traffic takes it up to 95°C, but at that point the thermostat should fully open.

I checked from somewhere;
I felt that those are kinda high, and the gap between amber/yellow and red temperature thresholds seems ridiculously narrow.
I've set an alarm in Torque at 100°C.

ps. you can type 0176 while holding down ALT to get the degree symbol (°)

 

My 2012 XKR runs at 195*F to 210*F during any weather at any time of the year I drive it. I consider this normal and don't have a concern. I think I did hit 215*F at one point in time but this is a non concern issue. Furthermore my 2016 5.3L Chevy truck runs at a normal 210*F temp. Considering you run antifreeze in a pressurized cooling system these temps are not a problem. Also looking at some race cars it is not unheard of them running at 240*F . Now if I did see 240 I would need to pull over buy hopefully I won't see the day. I also do monitor my WT during normal driving . Enjoy the ride.

 

Thanks for sharing your experience !
So I guess the temperatures were higher before replacing thermostat and sensor ?
If so I may replace as well...

 

Thanks, that’s all related to your 5.0 L engine.
I am not sure I should expect similar measurements on my 4.2 NA

 

I've only had my car for 6 days, but Torque has consistently been showing temps from about 193 to 212. If I'm sitting in a parking lot with the engine running it gets up to 210 and blips up to 212 occasionally. If I'm driving down the highway it drops to the 195 range. This is in North Carolina where the ambient temperature has been in the lower 90's the last few days.

I have the 5.0 supercharged engine.

I haven't been seriously concerned a out the temps, but I'm guessing I will have to replace the water pump at some point.

 

I see now that you are located in Finland so your ambient temperatures are way lower then what I’m experiencing
That may be just the difference between our experiences?

 

I had no apparent issues with the temp sensor, but the thermostat was stuck open. Due to that, the car struggled to reach above 70°C in winter conditions. Summer temperatures were normal from what I can recall without checking.

A 2014 thermostat should have many years left. I've heard the tend to go after 10 years or so, and the one on my car started misbehaving 12 years after the car was built.

Ah, well Israel is a tad hotter! A few days ago we got nearly 25°C here, which probably doesn't impress you much. Anyway, I don't remember ever seeing the 100°C alarm I've set actually go off.
Once I get home and have access to last summer's data, I can check the highest ambient & coolant temps, but it's unlikely to be very relevant to you after all.

 

When I got that message in my 4.2 it was the thermostat and water pump!

 

What can go wrong wit a 4.2. water pump ? Broken impeller?

 

I’m not sure it had a very tiny leak and I wanted to totally get rid of the faint coolant smell and I can Successfully say even if I drive the car hard there is no coolant smell

 

Yes

 

IIRC isn't the problem that a failing thermostat causes the car to run hot, and the resulting hotter coolant causes the plastic impeller to inevitably fail?

 

All water pumps usually have the same failure problems. Usually the seals will get worn and start to leak most likely through the weep hole. Another issue is the shaft bearing wear when the seal leaks because the sealed grease is washed out of the bearing. Then there is the impeller becoming loose damaging the inside of the pump. Then there are other plastic components in the system. The 4.2 is just a prone to failure then any other pump . It's just a matter of how good they were assembled and if the other components of the belt system are in good condition. My old Ferrari would burn out a WP every 15K miles until I had it rebuilt by a guy called the "Dutchman" . It had over 30K miles when I sold it and he would replace it up to 100K miles. Our old Volvo has 250K on the 2nd WP so it's all a shot in the dark here on life expectancy.

 

I was in there 2 months ago while replacing hoses
The impeller was intact
Not sure if all is fine or I should suspect the thermostat or radiator?