I think my 86 XJ6 is running a bit hot ......I just had the radiator rebuilt , changed the thermostat, new water pump , 4 new hoses , new coolant , both fans work good . the temperature guage is just to the right of center
( 90 ) and sometimes goes even higher lets say 110 . Any ideas on what might be causing the extra heat ????

 

Is this situation road speed dependant? If it occurs is traffic conditions but seems OK at highway speed then you can suspect an air flow problem....most likely a weak fan clutch.

Take the car for a good run and get it up to 90ēC-plus. Turn off the engine. Now give the fan a good spin by hand. If you get more than one revolution of the fan blade then your clutch is weak.


That said......

What are your ambient conditons in Spokane? Hottter than the hubs of Hades? My experiene with Ser IIIs is that they'll hold 90-ish degrees up until ambient temps reach about 90-ish degress....then the cooling system struggles a bit. Doubly so in traffic....even with everything up-to-snuff.

100ēC isn't too worrisome. 110ēC is getting "up there" a bit.

Cheers
DD

 

I am very sensitive to over heat conditions. I lost the DOHC in my S3 in about 2001. The low coolant indicater and the temperature guage let me down!!! Just past 90 seemed OK. The green line past that is very misleading!

The LT1 in my car is set to run hotter than the DOHC it replaced. Nevertheless, I watch it like a hawk!!! The new radiator is a big four row brass unit. Much heftier than the somewhat skinny Jaguar unit it replaced.

Yes, I think the cooling system had the foggy wet cool weather of the UK in mind. Mine seems happier when it is cool and wet around here, even in it's altered state.

I think the cramped quarters of the engine bay have a lot to do with the marginal cooling in hot weather. Relief louvres or NASA vents would be great.

Failing that, in slow traffic, crack the bonnet. A great escape for very hot under bonnet air has to help.

If there is any doubt as to an over heat condition, shut it down and await nightfall.

The combination of an alloy head on an iron block is issue enough. A marginal cooling system and disaster is nearby. Been there done that.

Caveat. On shutting down, the heat rises. A benefit of the fan in front of the condesensor for that purpose. I counsel, let it idle a few minutes with the bonnett cracked before walking away. if the fan clutch is not up to snuff, not a good idea.

 

Did you flush block before adding new coolant? What temp thermostat? Was this an aftermarket thermostat? Also, as above check fan clutch. An 86 XJ6 no matter the weather should be near upright on gauge.

 

Have you put in the correct thermostat ? As I recall, as it opens it closes the bypass port, and an extension on the thermostat has to be there to allow this to happen. If the bypass port is open, not enough coolant passes through the radiator to keep the engine cool.

Does your thermostat look like this one ?

Classic Jaguar, Jaguar E-Type Series 3, XJ Series 3, XJS Thermostat 82C (EBC3576-A) - JustJagsUK.com Series 3&q=

 

I did check the fan and it seems to be fine. the temp in spokane has been in the mid 90's , although she still runs around 100 and up in the cooler evenings and mornings.I plan to check on the thermostat to see if it's doing it's job. Any chance at all it may be a sluggish water pump ? Cheers, Kevin

 

A water pump problem such as a rotted-out or slipping impellor is always possible but it's bit on the rare side. You'd have to remove it for inspection....at which point you might want to replace it just on general principles if it looks to be original or even slightly suspect.

A much easier first step is to remove and check the thermostat. It might be not be opening all the way or, as mentioned, incorrect. Use an original Waxstat type.

Cheers
DD

 

I had a tough time finding a waxstat .........any good alternatives ??

Cheers KO

 

Google "Stant 45398" or "Stant 13398". Both look like the right configuration with the rear bypass disc and both are listed for Jaguar.

I can't tell if either has the steam relief hole but, if not, that's a 30 second fix with a 1/8" drill

Your local auto parts store should be able to get one for you.

Stant is a known good brand

Cheers
DD

 

Thanks Doug, Amazon has a bunch of em for $10
I made the mistake of using a fail-safe . A couple of folks in spokane mentioned that the fail-safe tends to run the engine a bit warm. hope fully this solves the issue !!

Cheers KO

 

I am having the same problem and join this forum just a minute ago to post this very same question. Anybody have any answer please...only difference is mines is a 85 XJ6

 

The cooling systems on these cars are not exotic and problems are usually solved in very ordinary ways. A clean radiator and engine block, good fan clutch, and a correct, properly functionng thermostat are all that's needed....usually...to keep the engine cool.

Cheers
DD

 

I need some help here before I start digging. Ths is the only link I could find that addresses this in a near similar car. I have a 2002 super 8 which is the xj8 vanden plas with a supercharger 103k miles.
I drove across the state yesterday and the radiator fluid light came on (low fluid). The temp gauge stayed low so I drove to an auto zone. They didn't carry the orange fluid so I added water to the top off. It did not seem low but the light went off and I had no further problems. 300 miles back and forth same day.
Today, I drove about 8 miles and when I turned off the car I noticed the high speed fan kept running. this never does this. The temp gauge was in the middle where it always is. I opened the hood and let it cool down. I added some orange fluid to the top off even though it was pretty full. I then drove about 3 miles to Staple, then the grocer store. The fan ran again at the grocery store for about 5 minutes. I drove home (5 minutes) and the fan kicked on when I parked it and the gauge red light was on and moving to the top. I shut it down and the high speed fan ran for 5 plus minutes. I checked the gauge and turned it back on. Gauge was normal, fan kicked on again when I was turning it off (2 minutes) and ran for about 2 minutes. The fluid does not look great and it def. is not orange. Today I drove it about 5 miles and the fans kicked on and the temp started to rise. I turned off AC, kicked on Heater and the temp started to drop down to normal pretty quickly. Thermostat? If so, how do I change it out. I can't find anything online to show me how to find it or change it out.


2002 Jaguar Super 8 -103000 miles Florida car

 

The new stant therostat made the differance , she now runs at 83 degrees Problem solved !!!!! thanks for the input !

 

Far out! Gotta love easy fixes :-)

Cheers
DD

 

Curtiss, I'd start with a flush and a new thermostat....but I'm not familiar with V8 cooling problems. Some of them had water pump issues, among other things.

Re-post in the X308 section. Lots of people there who are familiar with the V8 cooling systems.

Cheers
DD