Been reading up on v12 over heating after driving then park the temp keeps rising, on mine normal temp needle is just below N when I kill it turn back on 5 minutes later needle is at top of N. Research says this can drop a valve seat. Someone needs to come up with an electric water pump to run on timer with the rad fans.
Research says to raise hood to let heat out, at home ok, anywhere else I don't think so.LOL

 

Normal on most any engine for the coolant temp to increase after shutdown.

At "top of the N" the coolant is unlikely to be hot enough to drop a valve seat...assuming the gauge is fairly accurate. Sometimes they're not.

A more likely cause of a dropped valve seat is a steam pocket in the cylinder head. This creates a hot spot around the valves and can occur even if the coolant itself is well within the normal temp range. In other words, coolant *flow* to all areas is just as important, or even more important, than actual coolant temp. That's why V12 cooling systems need to be clog free, have good and correct thermostats, and be properly bled.

Open the hood if you want for venting of hot air. IMHO, if the cooling system is in good shape it isn't necessary. Surely can't hurt, though :-)

Cheers
DD

 

Doug you have helped me out on a lot of ?? and I thank you very much.
How do you properly bleed cooling system? I'm replacing hoses and have rad flushed.

 

I am curious to know if there's anything special about bleeding the cooling system on an XKS.

Otherwise, this guy shows the general procedure I've usually used to bleed my systems:


Not too tough!

Eskr

 

You're welcome, and scroll to post #9 in this thread

https://www.jaguarforums.com/forum/x...ine-bay-36778/


Cheers
DD

 

Ooops, wrong thread!

Eskr

 

It is a complex system and it is really important to make sure that there are no air pockets left in there.
Remove both radiator caps and open the bleed valve at the top left of the radiator.
Fill using the correct mixture of anti-freeze and water into the centre filling point until liquid oozes out of the bleed valve.
Close the bleed valve and replace both radiator caps and run the engine for a minute or so to circulate through the system.
Repeat the process a couple of times until liquid constantly comes out of the bleed valve.
Run the engine up to temperature and switch the heater onto full to circulate through the heater system.
Check for leaks, let it all cool down and then top up as necessary; it should be about 3 inches below the neck of the centre filler.
Off you go with a cool cat!

 

Dougs method also suggests raising the front of the car up. Thats how I did it. Even doing it properly, you may need to do it a few more times to be perfect. Based on the difficulty, I prefer to save up any cooling system work and do it all in one go with one bleeding session, rather than bit by bit.

 

You'll still have to bleed it more than once because it is such a convoluted system; air pockets mean no water present which means hot spots and potential (guarenteed)problems.

 

I have bleed 3 times so far, drive 10 miles with heat on and then bleed. First 2 times bubbles came up kept adding coolant till no more bubbles drive come back bleed bubbles add till no bubbles, the last time drove came back bleed add coolant no bubbles. Maybe it is good to go.

 

How is the temperature reading now?
Does the auxiliary fan kick in if the temperature rises above normal?

 

70* ambient heat gauge needle running about 3/16" below N driving. When parked idle aux fan kicks on when needle gets to bottom of N turns off when needle gets 1/8" below N. Doing much better now. Wonder how it will do when ambient temp is 103 plus* with AC on ?

This morning ambient 48* driving needle stayed half way between C and N.

 

It might struggle to keep temp under control in traffic. That was my experience, at least, when ambient conditions got that high.

Mine cooled fine in moderate temps regardless of driving conditions, and fine in 100+F temps if I was rolling right along. In *city traffic*, though, at 90-100ºF ambient, the needle would start creeping up. Never boiled over or even close...but there wasn't enough capacity to truly maintain coolant temp in those conditions

Others have reported better from their XJS, others worse.

Cheers
DD

 

I don't understand why Jag didn't make a proper Radiator.
All my Chevy's stay same temp from freezing to Hot as hell in bumper to bumper traffic ?????????

 

Mac, that sounds absolutely perfect and I don't think that you have anything to worry about anymore (on the cooling side at least).
Now, if you've got a spare half hour could you just pop over the pond and sort my overheating Cabby out?