Normal operating temp?
 

Having just sorted a cooling problem on my 2002 Sport, I use obd2 app to monitor temps when I am in heavy stop and go traffic. Haven't seen it go above 208 fahrenheit, then the fans bring it down to 194 and they turn off. Going to purchase the real temp gauge, and want to know what is the halfway point on our engines.

Also, is it the same for XJR's? Asking cause my dad just bought one:D

Unfortunately, the temp. is all over the map depending on the thermostat. I like 195- 202, but have seen low 180's to 205- 212.. The mid point on the gauge is 185, and that is where the Realgauage is set.

The new thermostat in my 06 is running 181- 186 and I'm going to replace it soon. I had the same problem with my Z4, so it's not just Jags. I use a Ultragauge to monitor through the OBD plug.

Sounds about where mine sits as well. I would like to change over to another range lower just for piece of mind. I did have it warm up quite a bit sitting in a traffic jam with the AC at the tail end of summer. Once I turned the AC off and the windows down, the temp dropped back to normal, but I find mine sits normally around the 194-198 range during normal driving. This is also a replacement thermostat from a year ago when I was sorting the aux pump issue I had. As easy as it is to swap though, I want to at least try a colder one and see how it does.

Curious to see how a lower temp thermostat would work. Ok so, as long as not above 212, I shouldn't worry?

Right, 212 isn't out of the realm of "normal" but if you see it sitting there in normal operation in moderate days, it might be worth a flush and a closer eye on it. I only saw elevated temps when I was either sitting still in warm days, or if I was really pushing up hills repeatedly in summer. Oh, and when I put it in the ditch and stuffed the grill full of snow. But that was just me :)

Still normal, but the higher end of normal. Please consider the 'RealGauge' option on my website when you upgrade. It has alarms for overheating and low oil pressure which can really save the day!

Mine is running around 200F (93C) under normal driving conditions.
Will run up to 210F in traffic, and to an incidental 220F in hot humid weather slow up a steep mountain.
I guess yours works perfectly fine.

By the way, I don't think a thermostat does anything for the higher temperatures, cause once it is open, it is open ...
In my understanding, the thermostat only protects the engine from too low temperatures (during warming up and winter conditions) by closing a part of the cooling circuit (rads and fans).

Good info guys, thanks! Well it is was in the low to mid 40s outside today. And the car will get up to 207 with the engine just idling in front of the garage, then the fans kick on and brings the temp down pretty quick. I do that on purpose just to make sure the fan I replaced is doing it's job LOL. But driving, yeah the temps come down very fast, fans on or not.

Of course, this is the gauge I was talking about! Read the install earlier today.

Eric, I think running to 220F under load might be too high and indicative of a radiator that is at least partially clogged. I know you are very meticulous in the maintenance of your car, but I would expect the fans to be able to keep it lower. My 97 would sometimes get to 215 in the summer and that would make me nervous. But you are in a climate even more extreme than Georgia in the summer.

Maybe I should have said it hit, just hit, as it triggered my 105C coolant alarm in Torque Pro.
And that on a slow steep upward, behind a truck, on a 40C degree wet humid day ....
The fans took care of it, and it was the only time it triggered the alarm.

The RealGauge from Steve is an engine saver - a breeze to install, just take your time. I think every XJ owner should invest in one. Super piece of kit.

I had a new thermostat installed when I did the housing etc. I haven't seen anything over 208° FH in stop & go summer as of yet & I am in coastal N.C. very hot & humid as well.

Recently fitted the RealGauge into my XJR, great bit of kit. I have been playing with the OBD monitor in addition and mine seems to sit around 85c (185ish) when on the move, and will rise up into the 90's (~200) when sitting in traffic. Ambient temp is ~10c at the moment (50ish F).

P.S. Found a couple of old XJR thermostats and they were both marked 84c which is 183f.

The reason for a pressurized system is to prevent water to steam -- coolant as well above 212f. Slow warm ups and the possibility of very long periods running under design temps is a real possibility in colder climates. I never run lower temp thermostats in modern cars. The cars have no problem maintaining safe temps in any climate if the system is operating properly.

Having the temps hit 210 is nothing to worry about.

Perfect, thanks!

My above post was garbled. Cooling systems are pressurized because when you place water under pressure you can heat it above it's boiling point. IE -- when it goes to a vapor. Obviously, you do not want this (going to a vapor) to occur inside your cooling system.

Modern engines like to run hotter vs what was common say 40 years ago ... they are more efficient. The coolant additive also raises the boiling point -- when combined you can overheat an engine and never have it boil over.

A pressure cooker works the same way -- things cook faster because you are raising the water temp under pressure.

185*F to 205* was the normal range I found on mine. Outside those ranges check for issues. Pressurization and coolant raises the boiling point well above 212*F, so you have room to spare, but the cooling system and fans were designed to keep the car in more moderate ranges under all conditions (heavy traffic in 100* plus; climbing mountains with a/c running; frozen Mn . . . ). 194* - 208* sounds like the system is working fine.

Well that makes me worry, as my temps were that in heavy traffic, but 70 Fahrenheit. Not sure what I should look for. Already checked the cooling system out.

I am missing something: it sounds perfectly normal!