Where is the coolant drain petcock on an 04 with a 3.0? If I look up through a hole on the passenger side in the air deflector under the radiator I can see a plastic pipe with a small piece that sticks down. On the bottom of that piece is an + that looks like a flat bladed screwdriver is used to unscrew it. Is this a plug to drain the coolant? Thanks.

 

Razkid, yes, that is the drain plug. No big deal but just a warning though, it will tend to drain down on to your arm unless you pull the plastic cover out of the way. TRUST ME!!!!!! Your call. I did it with the cover still installed, just need to be fairly quick.

 

Thanks Thermo. I took a chance and tried to unscrew it and found it was the drain plug. I didn't unscrew it all the way but I saw what you meant by running down your arm. I had tried to remove the cover but a few of the screws would have broken off so I kept it in place. Now my WTF question is how do you get the cap off of the coolant reservoir?! The cap unscrews and spins free but won't come off! What is the refilling procedure to remove the air in the system?

 

Razkid, try pushing down a little bit as you turn the cap. It may be possible that your cap is broken and is not working like it should.

As for the refilling procedure, I just filled the system and called it good. There is a bit of recirculation going on in the system, so, the air gets pulled out pretty easily. Personally, I would not worry about it. Drain the coolant, close the drain plug, fill up with the proper amount of coolant and then run the car at idle for about 5 minutes, finishing with topping off to the proper level.

 

Thermo, The cap unscrews to the top of the threads and I can screw it down tight. When I unscrew it to the top of the threads it just free spins but when I try to lift it off the whole tank lifts up. Maybe the top threads are messed up. I'll try lifting on the cap while unscrewing it to see if that works. I just didn't know if it was another great Jag design that you had to look for a hidden latch!

 

The cap does fit really tight on mine too.
What I do to get the cap off is place the flat blade of a large screw driver under the edge of the cap, then twist the screw driver with a slight upward movement until the cap pops loose. If you're careful this can be done without harming the tank. To put it back on I give the cap a sharp tap with the heel of my hand to get it seated enough so the thread will take hold and you're able to tighten it. I've done this several times without damaging the tank.
About the radiator drain. I replaced the plug with a nylon fitting. To the fitting I attached a piece of clear tubing, in the other end of the tubing I put a brass winged radiator drain plug. Now my radiator drain is in a position where i can reach it without making a big mess.

 

I applied upward pressure on the cap by using a screwdriver as a pry bar while twisting the cap and it popped off. GM- I hope you used hose clamps on both ends of the tubing to secure it to the fittings.

 

Yes, I used clamps and I've had no leakage yet going into the 3rd year of this modification. This setup sure make it simpler and less messy to drain the cooling system.

 

Yes, I have used clamps. After a couple of accidents with my set up catching on things and dumping coolant I've finally adjusted the length so it's protected and haven't had a problem and can still get to the fitting to drain it only when I want it drained.