Hello all new here.
I have recently purchased a 78 SII xj6 101,300 original KLM's via log book history. The temp gauge is telling me running between the A and L of normal, I'm in town driving slowly or parking etc it will go a needle width passed L on the gauge. Once I get moving at 60klm's or better for a few klm's it will come back to the A or L and stay there. It is hot here about 36c and high humidity. Here is a list of what I have done.
1. New Jaguar thermostat (car didn't have one)
2. Reconditioned flow tested radiator
3. Engine and heater core flushed before new radiator
4. New viscous hub
5. New Jaguar radiator caps
6. All coolant hoses replaced
7. Correct coolant added at correct ratio
8. All v belt replaced
9. Water pump checked( not leaking no noises no play in shaft
10. Rubber flaps replaced in radiator shroud
I have laser tested the system when on the L of the gauge and the hottest temp I have seen is 90c.
No signs of any thing else going on(pressured system etc)
Any suggestions as to what could be causing the fluctuations???? please.

 

what I would suggest is that you install an auxiliary cooling fan (a "pusher" fan) just like Jaguar did in the Series 3 XJ. It's the only thing not on your list.

you can buy a nice aux. fan kit online.

One thing I know, Jaguars run hot, it's an engine that likes it hot. And gauges are not always believable. You could replace the Temperature Sender just to confirm. it's not expensive and sooner or later you will need to replace it.

In hot islands and countries like AU where ambient temperatures are more or less hot year round, people remove the thermostats, it's of no use if you don't need a Heater. I would remove the thermostat unless you need the Heater.

Or just install an aux. fan and keep the t/s.
Or remove the t/s part of the year and put it back in Winter.

 

snip


It's 36ºC ambient and the hottest coolant temp you've seen is 90ºC?

No worries. That's as good as it gets. Move on to other projects.

Cheers
DD

 

Hey thanks for the suggestions.....I should have mentioned the jag has A/C so it has condenser fans, which are working. The owner before me has connected a separate thermo switch to kick in earlier. I hate removing thermostats, they are there for a reason. Having said that the car drove a little cooler without the t/s....... so do you believe running at 90c is alright???
Regards Russell

 

Ok, so Doug you think running at 90c is alright. I get concerned about water temps...paranoid actually.
Regards Russell.

 

Russell,

Welcome to our wonderful world.

Doug is spot on, as usual.

The temp gauge sender unit, on the water rail, with the singke Green wire on it is the #1 suspect.

I use Echlin, when I can get them. Tridon brand are also very reliable. TTS029 (Tridon) is the number of the ones I use.

Also whilst you are at it, check the actual engine earth strap/s, and make real sure that the engine is actually earthed TO the chassis, and not just the rubber insulated front cradle. This is a very common area that causes havoc with lots of electrical items. It will find an earth eventually, usually via the gear select cable and the "T" handle, but that is a scrappy earth at best.

 

I also have a XJ6-C 1977. I and it live in Phoenix; where the summer puts a massive load on cooling. I installed a flexfan in place of the regular and two electric push fans out front. I also replaced my radiator with an extra core radiator.


The flexfan is a little noisy, but really helped. Make sure you keep the radiator shroud; that's a must.


The electric fans allow the aircond to work decent even in stop and go traffic. You will want to get some kind of timer on the fan circuit so they can stay running after you stop the car. That will help avoid heat buildup when making many stops.


With custom radiators so easy to get these days I would start with an aluminum 4 core. add the other fans as needed.


Modern cars don't over heat, designed originally with reality in mind. go for overkill and thermostat back.


good luck geneo

 

Woops?


Myth busting time???


1. Thermostats not desirable in climes that are hot year around?


2. The XK engine likes it hot ?


Not to my way of thinking in either case.


???


Carl

 

you would need to have lived in the Caribbean islands to understand why the thermostat is not needed.

 

jag-cad


Sorry I put the comment about thermostats too encrypted for ya.


old jags and xj's run hot, having been designed in England. Best way to keep them happy and alive in hot climes is too over-cool and then use a themostat to help manage the temperature. Gotta have a stat or the water rushes through the block so fast it doesn't stay in the rad long enough to dissipate heat.

 

Thanks everyone, bit of conjecture re the thermostats.....I'll take it all on board. Bring on winter to help our gorgeous cars!!!!

 

I know this is an old thread, but still an existing problem on my 1975 XJ6C. I live in Florida and also have running warm problems especially with the A/C running. I don't seem to have a radiator shroud mounted anywhere. Can someone please provide a pic? I've looked in the parts catalogue I have and can't seem to find one. BTW I also have this cardboard-ish part that I don't know where it goes. Could it be the shroud?


Thanks, Bill

 

shroud around fan.

 

cardboard would not be so near to or at the radiator, that looks more like a hood insulation section, maybe the short section that goes at the widest part of the hood near the cowl.