I am pretty sure I have a head gasket issues but the symptoms are pretty weird. I've built a few BMW and Porsche engines so I am pretty proficient with cars but the Disco got me confused. The car is not overheating but it is definitely over pressurizing the cooling system while at the same time holding the pressure forever. I drove it this morning to work and there was coolant all over the front differential and none anywhere when you looked at the engine from the top. Later today when I got home I popped the hood and there was coolant all over the expansion tank and the right frame rail. I replaced the expansion tank cap a few days ago and it still won't hold the pressure so I am pretty sure it pops because the pressure gets too high. The weird thing is the coolant doesn't seem to be leaking back into the combustion chamber because it will stay pressurized even overnight and there is no white smoke when you start the truck in the morning. I already ordered the head gasket set and will start tearing the engine apart tomorrow, I just hope it is the head gasket and I am not waisting my time. The truck is a 2002 with 147K miles by the way.

 

I got a similar problem. sometimes it leaks a lot ( about a quart every week ) and sometimes just a little bit. I believe my leak is coming from around the waterpump. I have heard that leaks are common around the timing gear cover. its been going on for about a year. I keep a close eye on it. Don't have the time to tear it apart, need the truck to get to class. If you can get your pressure tested, you should be able to find out where your leak is coming from. I think this spring I will tear mine apart, and change some gaskets, plugs and wires while I'm at it. good luck, let us know how you make out.

 

Art, also order a new t/stat and head bolts along with any other thing you find along the way, like plug wires. If you have the old grey wires, order up a set of 8mm Magnacor wires.