I didn't know the big hex on the xjr was a coolant fill for the supercharger.. Is the coolant for the supercharger circuit tied into the coolant bottle? I am getting hot air out of the cooling system, on most cars that means the system is bled.. Am I good to go? Thanks

 

Yes, that hex plug is for the coolant level in the inter-coolers.
Correct way to fill and bleed this system is to remove the plug and fill gently at the expansion tank and allowing it to settle.
Give the top Radiator hose some gentle squeezes which will help purge air from the system.
Keep filling until the level reaches the top at the hex plug.
Replace hex plug, leave expansion cap off and start engine, let it idle for 15 minutes.
Stop engine, replace cap and fully warm engine at fast idle until cooling fans kick in.
Switch of engine and allow to fully cool down.
Remove expansion tank cap, check level and add to bottom of neck, replace cap and take car for a 50 mile return drive.
Allow to cool down and check level.
If all is OK you're good to go ;o))
The intercoolers are connected to the main cooling system and is assisted in circulation with the secondary cooling pump.
The cooling system on these cars is a self bleeding design and if instructions are followed properly, you have no problems.
Over a week or so , keep, a check on fluid level.

 

Great advice. I just wanted to add one thing : take a bottle of coolant with you on your first drive after filling! My low coolant light came on after about 5 miles, luckily I had a bottle of coolant with me. Had to add a couple of quarts. This is normal, just air working its way out. (and yes, I did warm the car in the drive, with the heater on, AND bled at the supercharger).

 

One more piece of unsolicited advice: Install a Real Gauge kit made by the Jag Wrangler, a member here.

It converts your "idiot" temp gauge to an accurate gauge. The factory gauge reads square in the middle until you have a problem, then shoots up to the hot region too quickly for you to realize the car had been running hot for some time.

The Real Gauge kit makes the temp gauge give your real temperature readings for your engine.

Cost is reasonable, installation is simple and includes detailed, easy to understand instructions and it includes an audible high temp alarm.

Our aluminum engines don't tolerate overheating and it is good to know how your engine is doing cooling wise.

RealGauge FAQ - TheJagWrangler

Vector

 

You can get an Ultragauge, which plugs into the OBD2 port, and gives access to every parameter available on the bus, including engine temp, horsepower, you name it, for half the price of that real gauge.

 

The Ultragauge is nice if you need all that additional data and you have to figure out where to mount it. I get most of the same data from Torque on my smart phone connected to a blue tooth OBD device, cost for that was about $20.

RealGauge is nice if you only want temp data, alarm and want to keep a stock appearance. The "ricer" appearance of the Ultragauge sticking on your dash cannot be denied.
Vector

 

"Torque on my smart phone connected to a blue tooth OBD device, cost for that was about $20."

Cool, must try that.

 

I use an Actron CP9575 and leave it plugged in and set to read data, hit ENTER three times after startup and it provides live temp and fuel trims. Cheap and easy.