I recently purchased a 1996 Land Rover Discovery with 175k. I bought it knowing i would have to put some money into it but just looking for something to get me through the winter. Drove it for more than 20 minutes for the first time today. I changed the oil checked all the fluids. after about 45 minutes the Car started over heating. Bubbling sound coming from the coolant reservoir. I let the car sit for an hour and the coolant was empty. Thinking head gasket. Engine is running fine no white smoke no milky oil tho. Checked both the fans which are working fine. Could it be thermostat or radiator? or could it still be the head gasket? planning on taking it in tomorrow just wanted to get a head start. Thanks.

 

Yep, head gasket for sure. They dont always mix oil with coolant or vice versa when they blow.
At worst it could be a slipped liner but more likely just a gasket.

 

thank you. hoping for the best here so i bled the cooling system. Did it twice (not sure if that is necessary) but both times 45 minutes. monitored the fans, hoses, and temp gauge. the gauge never went passed half way everything else seemed fine. Drove it around town all day and had no problems and the temp never went passed half way. hoping everything is fine but just going to keep an eye on everything.

 

You may be lucky and just have air trapped in the system but in my experience there will be an issue somewhere in the cooling system, could as simple as loose hose or a leaking freeze plug.

 

Or cracked coolant reservoir.