This is the repair I did on a 2003 DII. I bypassed mine but the owner wanted the correct repair. This 2003 DII has only been service by LRNA and LRSA. I am the first untrained and un-certified person to touch this DII. It just got the full 60k mile service done a few months ago. It is in immaculate condition.....except the throttle body gasket. So....
If your throttle body heater looks like this
and you are loosing coolant, do the following repair.
This is without removing the throttle body.
1. Remove the air intake arm. Open the cap of the coolant tank to relieve pressure.
2. Order part http://www.roverparts.com/Parts/MGM000010KG.cfm
3. Remove the crank case ventilation tube
4. Depending on the position of the clamps on coolant lines going to the plate, you can remove them now or later. I could only do the driver side first.
5. Using a 5.5mm 1/4 inch drive socket, remove the two rear plate screws.
6. Disconnect and set aside the vacuum lines
7. Remove the front plate screw
8. Take a rubber glove and cut off one of the fingers and cover the vent pipe for the valve cover
9. There is a good chance that after removing the screws, the plate will still be "stuck" onto the throttle body. Take a screw driver and lightly tap the plate until it falls off. Some coolant will be dispensed and some may be under pressure.
10. Inspect the inside of the throttle body heater plate. Still think Dexcool is safe?
I used two pliers to hold the plate steady and remove the coolant lines.
11. Comparison of the new and old plate
12. Clean up everything. I used a wire brush and mild solution.
13. Clean the underside of the throttle body too
14. Install new plate and position the clamps in such a way that you can remove them easier next time.
15. Take the gasket and put a LIGHT bead of Permatex right stuff GREY. Both sides (that is what I used to seal the t-case swap and no leaks!!)