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!

In traffic with the AC on .... this is going to test the system -- it's all fans as the is not moving and the heat from other cars raises the temp around the front. There is nothing wrong if the temps go up .. as long as they come down when the fans come on.


If the coolant temp was high and no fans came on -- that's a problem. It's also a problem if the fans are running and the engine is still too hot.

Your car is not doing either.

A working cooling system should keep the engine around 20° warmer than the thermostat opening temperature. So, if you have a 180°F thermostat, coolant temps should stabilize around 200°F. It should do this regardless of the outside temp (IE: from 0°F up through 120°F).

Since your car is doing this, it is behaving normally.

Might be an idea to blow out the rads to see if that helps with the temps, they could have a load of road kill in the vanes, also check that the flaps are closing completely they go hard and don’t seal, this reduces the rads efficiency

In my experience it's wider.

The XJ will turn the fans on low when the coolant hits 203 and they shut off when it's dropped down to 194. If the temp climbs to 221 the fans switch to high and they will stay on high until the coolant drops to 212. Obviously -- they don't shut off at 212. But, go to low. My fans will often switch to high in the summer -- so going to 221 is nothing to worry about.

The fans are also controlled by the AC system .. so things can change depending on pressure. My fans run on high often in the summer when I'm not moving much.

I just went for the first ride in weeks.

As I was not sure anymore I stated the truth before, had a good look at the OBD2 readings.
Took her for a spin through the hills, in moderate spring weather (20C-68F), with the heater at 21C=70F, and the airco off.

Slowly climbing, she ran up to 93C-199F, slowly descending the temp dropped to some 88C-190F.

Idling afterwards showed the exact as Yeldogt states: fans come on 96C-203, and stop once down to 90C-212.

All this is with ~1yr old thermostat and coolant.

Yeah it's been warming up here as well. Drove the car a lot yesterday, and temps were fine. Now to find time to install my new real gauge.

The time to check is on a warm day where you can stress the cooling system a bit .. without the AC running I'm not sure what I would have to do to get the fans on high .. I really forget. With the AC on and running up the RPM's I can get them on high. As long as I know they are running (on high) and sound normal ... know I'm good.

Both of mine have only received basic maintenance -- one is due for coolant refresh this summer.

Brining this back! Sorry! So today in HEAVY stop and go traffic, car went as high as 214 Fahrenheit with AC on. Ambient temp is 99 Fahrenheit. It wouldn't go below 214 unless I started to move. Worry about it, or not?

Not serious, but I think the fans are not moving enough air if it drops when you start moving.

As you know, since this thread start, I watch mine with extra care.
I should say, in itself, considering the situation and surround temps, 214 is still not too dramatic I think.
However, if I was you, check the fan speeds in such situation as you can .. just to be sure.
Also, are all flaps in place in the fan housing?

did you read my post #24?

+1 Normal operations. See his #24

I was cursed with an x300 that never had a problem for three years, so I've done no research on the acceptable ranges on simple things. The X308 I have keeps about 190* as if the graph line on my OBDII reader is a painted line. I am in Central Florida where 60*F is rare and today was 93*F - the AC is always on and I'm usually in stop and go traffic.

My 40 year old Jeep with engine driven fan is never over 195*, but my '86 Pontiac will get to 235* before the electric fan even kicks on (by design). If the AC is on it never goes over 200* because the fan is on all the time.

The pressure cap an the x308, as I have read, is 17PSI, which would correlate to a coolant temp of a bit over 240*, so I assume, for my personal worry list, that 230* is where I should get concerned.

FWIW

Thank you everyone! You can never be too sure these days.

Got up to 216 fahrenheit, this was in traffic with the AC on. 103 fahrenheit day. I notice with the AC off, car runs cooler. I know a poster said 220 fahrenheit is ok, but I'd like to stay at 216 max.

Are there any cooling mods we can do the NA cars? Yes, all the flaps on my radiator shroud are there. Sorry if I am being annoying, but I know these engines don't like to over heat.