I apologize in advance because I strongly suspect this subject was discussed here many times before... I tried the search option but was not able to find much useful info about V12 air bleeding. (Found couple of posts on 6cyl Jags, which is essentially self-bleeding. But did not come up much with info on V12)

So, here it goes. i drained and refilled my cooling system last weekend.(Also replaced thermostats at the same time.) I followed the instructions in the manual when refilling. Remove air bleed bolt on LHS. Fill in through remote tank as much as possible. Then fill in through the center filler.

If I want to make sure there are no air pockets left, what are the additional steps I can take to try air bleeding the cooling system?

 

I think Greg has a write up on this, where as you jack the front left of the car, so that the bolt hole is the highest part of the car, start the car, put the heating system on defrost and carry on filling the system allowing it to get warm and open the thermostats.

Personally, and this is an opinion share by others too, the system doesn't need this procedure. Fill up as much as you can, close the bolt and lids and then start the car. Turn heated to defrost and let it warm up. Then check fluid level again. Done... Technically, the hose and pipes connected to the top of the radiator act as bleed pipes and feed into the top spout (highest part of the cooling system).

 

I agree with Damien. Don't over think it. I used basically the process he outlined and that was 2 years ago when I changed the coolant and I have never had an overheat.

 

Not quite, but close!; this is my method as posted in this thread, post number 8. It is not really any different from what you guys do, but spelled out a bit for people who are new to the terrifying-looking HE cooling system:
https://www.jaguarforums.com/forum/x...r-help-185295/

1. park the car on a slope nose up, or jack up nose a bit
2. remove both caps and top up at centre cap until water starts coming out of the wing tank
3. replace wing cap and keep topping up the centre and replace centre cap when upright tube full
4. turn heater control to DEFROST
5. start the car and let it tick over for a couple of minutes
6. on the LHS (US driver's side) of the rad is a brass plug (at least on all OEM rads) roughly in the opposite position from the banjo bolt.
7. remove this plug and let air bubble out, squeezing the top hoses is a good idea to aid this process. If air is in the rad and no more bubbles, pour coolant into the bleed hole
8. turn off engine and top up into this bleed hole if necessary and replace the plug
9. remove centre cap and top up to the top of the upright tube.
10. remove wing cap and top up if needed
11. check centre cap level and wing tank level after doing a decent 20 mile drive after the car has cooled.

 

the way I do it is take off or out the bleed screw, and via the expansion tank keep filling until water runs out of the hole, that's it and it has always worked for me with perfect cooling.