I just received my AutoEnginuity OBD code reader today. I have been questioning the fact that my cooling fans seem to come on, even though it is still pretty cool in my neck of the woods. the air temperature is around 50 degrees F. The engine temp shows around 210 in normal driving, and when I climb my driveway, which is about 1/2 mile uphill it hits around 227. The fans come on and it cools back down to the 215 mark pretty rapidly. It has never boiled to my knowledge. I have a Cadillac that has a digital temperature indicator and it runs in this general range, but that is in the summer with the A/C on. I am a little concerned that if it is working this hard to stay cool with the winter temperatures, what will happen when it warms up and I run the A/C. Or maybe it is doing exactly what the designers intended. I am not looking for trouble, but if I have a marginal system I would rather deal with it sooner than later.
The other thing I found is that my long term fuel trim is running around 13 to 15%. I assume that is not a good thing either.

 

Change the thermostat.

 

Think I'd start with a thermostat too. Mine only ran ~198-202 F with an outside temperature of 100+ degrees during the summer with the A/C on high. It is currently in the 50 degree range here during the day and it runs around 195 F in city traffic.

And what's up with that one odd Dodge in the stable?

 

+1 on thermostat changeout. I had similar issues to yours, fans were engaging almost immediately when they had never previously done that, and then one day going up a hill, it nearly overheated. I changed t-stat and have had no further issues.

 

Hi Mike, thanks for the input. I guess I will change the thermostat just to be safe. As for the "odd Dodge", that is not really the only odd thing in the stable. I also have a 1972 International fire truck and a 2004 Jeep Rubicon. And a '93 Cadillac touring coupe,and a 2006 Ford motor home,a 2003 Goldwing and a 2009 Suzuki,and last but not least a Kawasaki 650 Brute Force ATV. It is a sickness...... Oh yeh, and 2 dirt bikes

 

I also would change the thermostat, It can be tested in a pan of water on the stove. Heat the water with the thermostat fully immersed in the water and monitor the temp. with either a candy thermomiter or a ir thermometer as the water heats. I find the candy thermomiter works best as it is immersed in the water. Just dont tell the wife what you have been doing in her kitchen. Not to change the subject but that is what I did last week with mine as it turned out it failed closed, My 97 XK8 overheated in an instant and blew the bottom off the coolant recovery tank. Even at 220 degrees the tstat didnt open.


D. Meyer

 

It's good for me to keep reading these stories.

I'm now of the opinion that the therms should be replaced 'prophylactically'

That is, as a preventive measure once the car is several years old.

They all go bad eventually and the potential damage is sobering.

 

We need to sort out your LTFTs once your overheating problem is cured.
Both banks?
Any other codes ?
Do a hard reset
https://www.jaguarforums.com/forum/x...ect-faq-74146/
BE SURE YOU'VE GOT THE RADIO CODE FIRST
then see what happens to STFTs and LTFTs.
If they're still up the creek I'd start a new thread once you've looked at the various possibilities already listed here.

 

There was no mention of what RPM the high STFT was at. If it's very high at idle and not so bad at speed, this can indicate a small vacuum leak where unmetered air is getting in but is lost in the total volume being consumed while actually driving.

 

Charlie
His LTFT is hard against the stop (we don't know if it's one or both banks).
If it's both it is probably, as you say, a vacuum leak downstream of the MAF.

 

The LTFT is (roughly) the same on both banks,and it is higher at low RPM,s. I also suspect a small air leak somewhere.
I read an excellent explanation of the operation of the STFT and LTFT here on this forum, so I think I understand how they work.
That said, I am constantly amazed at how many of you are willing to pitch in and try to help. This is the second best thing about owning a Jaguar!

 

Do let us know how you get on - it always helps others in the same pickle.