my 2000 Disco II is overheating. Once the car is running for 10 mins it will overheat. my coolant is fine and I just replaced the head gasket

 

make sure the cap where you pour the coolant is tight and is not letting any air out.

Once i spent months diagnosing the problem, spending hundreds, and all it was a little crack in the cap. all pressure was off. just my 2 cents

also take a look at the thermostat, those things go bad in discos and can give faulty readings.

all best

 

Make sure that you have bled all of the air out of the system. (If your heaters blow cold while not moving or hearThere are several methods to do it, many recommended, many not recommended (everyone has a different method/opinion). The RAVE manual has a recommended way as well.

Disco Mike says:
It is amazing how many wrong was there are posted on how to do the proper bleeding of a D2.
You only bleed the engine when stone cold, not warm or hot, not with the engine running or the cap off and running.
Remove the bleed screw, do not just loosen it, fill thru the coolant bottle using the proper amount of coolant and water, 50/50, and add coolant till you get a steady stream of coolant coming from the open bleed screw hole. Once you have coolant coming out, replace the bleed screw, then the coolant cap, start the engine, turn both heaters to full hot and allow the engine to idle up to operating temp, where when hot the heater should now be running warm at idle, if not, you still have air in the system and will need to let the engine cool down and re-bleed one more time. Never rev up the engine, trying to get the engine hotter quicker or the coolant surge on a full coolant bottle can pop a line.
I usually always suggest that the next morning, before cold starting the engine, check and top off the coolant bottle for any loss and check it again around a week later, always when cold not warm or hot or the level will not be accurate.

Also, if that seems to be fine pressure test to make sure you don't have any other leaks.

 

1) buy an ultra gauge if you don't have it. It is critical you know what the temps ARE and not go by the needle.


2) Probably the T-stat. A great time to get your 180 TD5 stat and swap it in. Next on your list should be to check the radiator, but after doing the T-stat and visually checking the fans (both electric and viscous) it be comes easy.


But the key to all of this is the $70 ultra-gauge! Or any other OBDII reader that can get you the actual temp. output. You can't troubleshoot anything when your only "sensor" stays in the middle for about 50 degrees and won't budge until it is too late.

 

In addition to what Disco Mike says, be sure to remove the overflow tank from its clips and elevate it as much as you can, so that it is higher than the bleed screw, then put the bleed screw back in once you get a steady stream pouring out of it. All this while the overflow tank is still elevated.

Once the bleed screw is closed put the overflow tank back in its place and top fluid to the line.

 

You don't have to remove the bleed screw completely...that's what the notches in the threads are for.

 

I just elevate the tank and run it at high RPM for 10 minutes.
This is how a Discovery I bleeds itself and a D2 will do the same thing.
I never touch that bleed screw.