how does one properly burp the cooling system on the 5.3 v12 ?

 

Jonathan,

I've moved this question from the end of your Intro to XJS forum. it's a long time since i had a V12 but I recall bleeding the cooling system was awkward.

Members here with the same model will be able to help.

Graham

 

V12 cooling system bleeding:

There are different opinions on what works for filling and bleeding but most owners follow the same basic procedure. Here's the process I used on my '88 XJS V12 and a few others. It's not difficult, just messy.

Elevate the front of the car about 8" and then elevate the left front another 2-3" beyond that. Set the climate control for max heat so the heater valve opens.

Remove the bleeder plug from the left radiator tank. You'll see an access hole in the radiator upper mounting panel. The plug is some arcane size but you'll find something in your toolbox that fits.

Remove the caps from the expansion/header tank and from the filler pipe at the front of the engine....up there by the A/C compressor.

Add coolant/water to via the filler pipe until it reaches the bottom of the pipe. Start engine, set heater control to max heat. Let it run at idle until it warms up. Peek inside the filler pipe every minute or so and top up as needed.

When the engine gets warm increase the idle to about 1000-1200 rpm (a helper is helpful here...or just wedge a little something in the throttle linkage to hold it slightly open for a high idle.

Let 'er run and run. Give the upper radiator hoses a few squeezes now and again. Keep checking your coolant level in the filler pipe and top off as needed. Eventually you'll see some coolant coming out of the bleeder. That's good. Wait a while longer and (hopefully) you'll see coolant *really* pouring out of the bleeder. (How much? It's one of those "you'll know it when you see it" things..very messy)

When it's *really* pouring out of the bleeder hole, put the plug back in. Wear some gloves so you don't get scalded. If you can't get the plug back in thru all the gushing, shut off the engine and do it....but I like to leave the engine running if I can. Not worth getting burned, though.

Top off the coolant in the filler pipe...I go right to the top but some fill just to the bottom of the neck... add a quart or so to the expansion tank if you suspect it might be low, button everything up, and yer off to the races. If you've overfilled the excess will be pushed into the atmospheric tank mounted inside the fenderwell. If you've *really* overfilled the excess will exit the atmospheric tank and end up on the ground.

Lower the car and clean the driveway :-)

Cheers
DD

 

Hi Jonathan, welcome to the forum! This has to be one of the most requested procedures - I'm sure Doug will be along to post his method. I think that's the one I see referenced most.

[edit] beaten to it by a minute

 

I posted the procedure. Again

As often as this comes up I wonder if it might be time to put it in the sticky thread section?

Cheers
DD

 

Be absolutely positive that you use thermostats with the bleed holes and jiggle pins (placed at the top on installation). If you don't use this style of thermostat you'll never bleed the cooling system.

 

Sticky it!

 

Nothing to do with the method itself but when I replaced my radiator I also replaced the bleeder plug itself with a petcock like used for a radiator drain on older US cars. Much easier for me to close the petcock than screw in a small pipe plug when the coolant is pumping out.

 

I swapped my valve for a communal garden domestic radiator bleeder valve
undo it while initial filling and slowly fill till water comes out of it instead of air,

 

Thanks every one... I will have peace of mind now and reduce problems on the heads now know this and using it...
Thanks again!