Took my car for a run yesterday, about 10-12 miles out and 10-12 miles back , its a 6.0 V12. When we got back the cooling fan switched on and ran for what seemed an eternity..... is this normal or does it mean something is running hot or a problem with the thermostat? Everything else seems normal but I also wondered if it is a drain on the battery? Does anyone else have this?

 

The car's auxiliary electric fan will run after shutdown (assuming the 6 litre cars are like the pre-facelift cars in this respect) if the thermostat senses the coolant is too hot. If you are in the UK, it is most unlikely this should have happened in April if the car's cooling system is up to snuff.
I suggest you have remove the radiator and clean out all the rubbish that will be stuffed in front of it (this occurrence is inevitable in an XJS for some reason), between it and the oil cooler/aircon condenser. While doing this replace the thermostats and the temp sensor for the fan. Also have the rad checked for any blockages etc.
Greg

 

You may have a problem but it is far from certain. What is the context of "when we got back the cooling fan switched on" if you got back and delayed shutting off and had car idling for some time after a good run the system may simply be doing what it should.

 

Hi tommygent

I also live in the (UK) and what you are experiencing (in my book) is quite Normal, even for this time of the Year (April)

My Car runs Cool in all Weathers and even in High Summer, the Temp Gauge never goes over the halfway mark and in fact it tends to stay in the

bottom quarter.

When you switch the ignition off, the Auxiliary Electric Fan cuts in and can run for quite a long time but I've never had a problem with it draining

the battery.

Following a suggestion from 'Greg' after I've been on a run, when I get back I open the Bonnet/Hood to Cool the Engine down quicker.

If you do that, then the Fan doesn't run for so long but either way it's never been a problem.

I would be a lot more concerned, if the Temp Gauge ever went near the Halfway Mark.

I would just add a 'rider' to that in as much as on an XJS those Temp Gauge readings can vary from Car to Car, so you have to get a feeling of

what you think is Normal on your Car.

But if the Gauge goes more than half way up, then I'd start getting concerned.

 

I have experienced this in my 87 XJS and my 87 XJSC when at my southern home more than my northern and knew that my sitting with the engine idle had contributed to the fan running a little longer.

Thank goodness it is doing its job.

 

For comparison's sake, my aux fan hasn't run after shutdown since the weather cooled down. Right now we're hovering at daytime highs of no more than 15 degrees Celsius, however. About the same as London and vicinity. Perhaps your run, while short, was pretty hard?

I also do the open bonnet thing after a decent run, if it's safe to do so (and I know it won't get rained on). Just an hour or two will help lower temps under there quite a lot.

 

As you describe it, it sounds like time for radiator area clean-out as Greg mentioned or possibly a radiator re-core. I did a very similar run today and it's 25C (77F) here, and the auxiliary fan never came on. Keep in mind, I put in a lower temp sensor that kicks the fan on 82C which is lower than factory spec.

If your system is in good shape, and you're in the UK, I can't imagine the auxiliary fan needing coming on even if you had a hard run. There is something odd to the XJS aerodynamics that pulls lots of junk into the radiator fins, so at a minimum I'd follow Greg's advice.

 

I seem to remember one of the more tech-savvy members, perhaps Greg or Doug or the WOZ, putting a mesh grille behind the lower standard grill to try and catch some of the leaves and stuff. That might also be something to look into, after you try and look into the radiator slots....