2003 hse range rover, overheating, the truck will sit at an idle and not over heat ever as soon as you start to drive you lose heat and the temp gauge goes up, heat comes back and instantly the temp gauge shows normal, brand new thermostat and housing. if the temp gauge goes up and you lose heat if u sit at an idle in drive slowly u have heat and the temp gauge shows normal. any ideas? head gasket? no coolant loss.

 

I would have your exhaust sniffed for coolant and check your oil for any signs of coolant too. Did you have your cooling system recently serviced (when did you have your t-stat replaced, and was it with an OEM or generic part), was it bled properly, etc.?

 

dealer had done the thermostat so im sure it was bled properly, its just been recently the problem has started 113k, 89k the t-stat was replaced it has been awhile. Im thinking its a head gasket

 

You might be right about it being a gasket. It could also be a number of other things, so make sure that is what it is before the engine is taken apart. Your radiator might also be plugged up. One easy test... Wait till the car warms up and see if the coolant hose is stiff when you squeeze it, that will tell you if the cooling system is pressurizing. Careful not to burn yourself of course .

 

Before you replace the headgaskets, it sounds like it could be just low on coolant.

 

Find someone with a block tester or buy one and check for carbonmonoxide in the coolant reservoir. that will tell you for sure. But also make sure you have all the air out of the system. You can also drain it and refill it using a vacuum filler. Engine needs to be cold and you will need a air supply (compressor). If the blue fluid turns yellow.....cry!

 

possible low on coolant but also a few leaks going on.