Hi guys, I am new to the forum because I just bought an 03 Disco for my wife. I bought it knowing it was overheating and basically suspected a head gasket because the PO replaced the water pump, thermostat and radiator as well as many hoses. I assumed he replaced them and it still overheated so he gave up on it.
So I bought a head gasket set and the throttle pre heater because that was leaking and replaced both. The old head gaskets looked ok and showed only minor signs that combustion could have been leaking into the coolant passage. Heads were flat and block looked good. Also there were no signs of coolant leaking into the combustion chamber, all pistons were black with carbon.
I can let it idle in my driveway for 5 minutes or so and it will hang right in the middle of the gauge. Once I go drive it down the street it will stay there for 30 seconds or so then quickly rise and overheat, like within 5 seconds of moving off half mark it is in the red and coolant is purging out the surge tank.
It does it every time. I dont understand whats going on. I even put another new thermostat on it but it still overheats almost randomly when you drive it. When I had it apart I inspected everything carefully, all coolant passages were clean and unblocked, even took off the new water pump which was good, fan clutch is strong, there are no leaks now. At first I thought I hadn't bled the system well enough but I redid everything and bled it from the upper hose connections.
Should I suspect a cracked head? Something wrong with the block? I didn't take the heads to the machine shop but I have a straight edge and the surfaces were good, even still the coolant passages are only on the two edges of the heads. Am I missing something?
I am a GM certified master tech, ASE master tech and I have extensive Kia/Hyundai training. I don' think Ive ever been stumped by a cooling system before. I bought the 03 because I read of improved head bolt design causing less gasket failures and cylinder liners that were improved. I really really don't want to buy a new engine or head.
So I bought a head gasket set and the throttle pre heater because that was leaking and replaced both. The old head gaskets looked ok and showed only minor signs that combustion could have been leaking into the coolant passage. Heads were flat and block looked good. Also there were no signs of coolant leaking into the combustion chamber, all pistons were black with carbon.
I can let it idle in my driveway for 5 minutes or so and it will hang right in the middle of the gauge. Once I go drive it down the street it will stay there for 30 seconds or so then quickly rise and overheat, like within 5 seconds of moving off half mark it is in the red and coolant is purging out the surge tank.
It does it every time. I dont understand whats going on. I even put another new thermostat on it but it still overheats almost randomly when you drive it. When I had it apart I inspected everything carefully, all coolant passages were clean and unblocked, even took off the new water pump which was good, fan clutch is strong, there are no leaks now. At first I thought I hadn't bled the system well enough but I redid everything and bled it from the upper hose connections.
Should I suspect a cracked head? Something wrong with the block? I didn't take the heads to the machine shop but I have a straight edge and the surfaces were good, even still the coolant passages are only on the two edges of the heads. Am I missing something?
I am a GM certified master tech, ASE master tech and I have extensive Kia/Hyundai training. I don' think Ive ever been stumped by a cooling system before. I bought the 03 because I read of improved head bolt design causing less gasket failures and cylinder liners that were improved. I really really don't want to buy a new engine or head.