Hey friends!
I could really use some help. I have a 1996 ragtop XJS. I love my car, but it has run hot from the first day I owned it. I have had the coolant system, etc. checked up and down, and even an experienced Jag mechanic says he can't figure out why this car runs so hot.
Any ideas? I would love some feedback.

Lynne

 

Hi

Six cylinder, I presume?

How hot is "hot"? Does it boil over or....?

What work has been done/ checks performed so far in an attempt to solve the problem?

Cheers
DD

 

Every XJS (and every Series I,II,III XJ sedan) needs the radiator core 'rodded-out' every once in a while. I must have done hundreds in the 1980s and 90s. I always asked the radiator shop owner if it was clogged and he said "I'll let you know if one is NOT clogged"

I aways wanted to know because I would have to look elsewhere to find the 'running-hot' problem.

Sometimes it was a slight head gasket leak or a sticking thermostat but mostly it was a clogged radiator.

I have a 1996 XJS 4.0 conv. in my shop right now and the radiator is at a radiator repair shop to get cleaned out.

The engine runs hotter the faster you drive and cools down alot when you just idle the engine. I called the repair guy and he said the bottom rows were filled with deposits.

I will pick up the radiator and reinstall it when the guy calls later this week. (maybe Sat??)

The later cars with plastic/aluminum rads don't seem to clog like the older ones.

bob gauff

 

Lynne,

I've moved your thread from General Tech Help section to XJS section as overheating appears to be a regular issue for owners of this model!

Graham

 

Bob,

Back in the '70's when I was running and repairing Series I and II, Jaguar in the UK recommended the addition of Barrs Leaks as a standard service item.

I always detested this stuff and have seen plenty of radiators and cylinder blocks clogged up with it. Was it also used in the US?

Graham

 

Thank you so much, guys, for all your great input and advice!
Doug, the car always runs above normal, but can go into the red if the day is hot, driving at faster speed or hills, but it never actually boils over.
I've had the thermostat replaced 3 times, coolant hoses checked and some replaced, radiator checked for leaks, etc.
Bob's idea sounds very likely. I've never had the radiator cleaned, and as far as I know, it never has been. This certainly makes sense!
I've heard from others on Jag Forums that certain models have this problem, but I would love to fix it. running this hot constantly is, I know, causing subsequesnt problems as well. It's a vicious cycle.
Thank you again for your help!
Lynne

 

By all means have the radiator removed and professionally cleaned. There's a good chance this will solve your problem but, even if it doesn't, it must be done to eliminate it from the "could be" list.

Cheers
DD

 

Is it really hot or is the temp gauge wrong?
RagJag

 

Yes, it's really hot... unfortunately. Can smell the heat, and the engine cooling fan runs like crazy when I've stopped.
Temp. gauge is good. But thanks for the thought!
I will definitely have the radiator cleaned, and let all of you know the results.
Thanks again so much!
Lynne

 

I guess the dealers here in the US got the same info.

We were given a pack of tablets to add to the cooling system with every service. I still find tablets in my toolbox every once in a while tucked into corners.

bob gauff

 

Hello again, Friends, especially Bob and Doug, who were both so helpful to me previously regarding my radiator issues on my 1996 XJS.
I could use a bit more advice...
I have arranged for a thorough cleaning of my radiator as suggested, and now a former mechanic friend has asked if I plan to replace the thermostat, water pump and hoses as well. His comment is that if the radiator is contaminated ("choked") the same contaminates may exist in the pump, etc. and will simply push these into the cleaned radiator, causing the same issue.
I have never heard this, and didn't consider it. I certainly want to keep costs to a minimum, yet at the same time I don't want to be foolish.
What are your thoughts?
The thermostat and upper radiator hose have both been replaced recently.
Thanks again for your input!
Lynne

 

Lynne, if you are going to go to all that trouble, then you may as well flush the engine water ways at the same time. At least then you will know it is contaminant free.

 

+1 on this. I would replace hoses and flush. I would not necessarily replace the water pump.

Just one observation though, have you actually measured the temp of the coolant at the exit of the thermostat? The reason I ask this is that the temp gauges on these cars are notorious for giving wacky readings. Having the engine rodded is certainly no bad thing but I'd want to check that I actually have a problem first

Cheers,

Allan

 

Ive had three low mileage XJSs over the years and the hoses and flush has been the best preventive maintenance. I've also had at least a half dozen hose failures over the years. This is due to the complex routing, heat and "dry rot" in the SW USA.

Most auto manf. recommend whole coolant flush & fill every 3-5 years. I don't even do that often. The best preventive maint. has be be anti-freeze and using distilled water to refill also. The anti-scalant properties of anti-freeze are consumed after a few years and these cars are expensive to replace coolant/corrosion effected parts. I spent 8 hours replacing a water pump & R&R radiator to rod out on my '89 XJ-S Marelli V12.

 

Thank you so much, guys, for the tips and info. This really helps me out a lot. I've been dealing with these issues for several years now, and I would love to resolve them, finally.
You have given me some great advice.
Lynne