2003 4.6L XLT overheating
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2003 4.6L XLT overheating
2003 F150, 4.6L 2WD, 185000miles
My truck overheated on me about 3 weeks ago. Looked in the reservoir and it was empty. Filled it up with some water after it cooled off and then drove home. I flushed the coolant system that weekend and the radiator sprung a leak on me so I replaced it. I also replaced the thermostat, water pump and fan clutch as well. To make sure I didn't have an internal leak I did a pressure test on the system from the resevoir at 16psi and the pressure held. Then with the with the engine running I used a block test kit where you fill a tube with some blue chemical that will turn yellow if exhaust is in your coolant. Coolant stayed blue so that test passed. After feeling satisfied that my truck wouldn't overheat, I drove to the store and overheated on the highway. Its been overheating randomly ever since.There are a couple of symptoms that happen every time it overheats:
Heater goes cold
Before the temp gets to the RED I pull over and shut off the engine. The upper radiator hose is rock hard at ambient temperature and the reservoir looks swollen.
In order to get coolant moving, I crack open the reservoir cap to let air escape and I can hear the rush of coolant through the upper radiator hose and it is piping hot.
After doing that, I can start the engine and the heater will be hot and my truck won't overheat.
I don't know how I'm getting air into my coolant system. I don't see any external leaks. I placed some cardboard under the truck and checked it in the morning and saw nothing. Pressure test held. Block test is sat. I also don't have any white smoke emitting from the pipe. I don't smell or see any coolant in my cab.
Anybody have any ideas?
My truck overheated on me about 3 weeks ago. Looked in the reservoir and it was empty. Filled it up with some water after it cooled off and then drove home. I flushed the coolant system that weekend and the radiator sprung a leak on me so I replaced it. I also replaced the thermostat, water pump and fan clutch as well. To make sure I didn't have an internal leak I did a pressure test on the system from the resevoir at 16psi and the pressure held. Then with the with the engine running I used a block test kit where you fill a tube with some blue chemical that will turn yellow if exhaust is in your coolant. Coolant stayed blue so that test passed. After feeling satisfied that my truck wouldn't overheat, I drove to the store and overheated on the highway. Its been overheating randomly ever since.There are a couple of symptoms that happen every time it overheats:
Heater goes cold
Before the temp gets to the RED I pull over and shut off the engine. The upper radiator hose is rock hard at ambient temperature and the reservoir looks swollen.
In order to get coolant moving, I crack open the reservoir cap to let air escape and I can hear the rush of coolant through the upper radiator hose and it is piping hot.
After doing that, I can start the engine and the heater will be hot and my truck won't overheat.
I don't know how I'm getting air into my coolant system. I don't see any external leaks. I placed some cardboard under the truck and checked it in the morning and saw nothing. Pressure test held. Block test is sat. I also don't have any white smoke emitting from the pipe. I don't smell or see any coolant in my cab.
Anybody have any ideas?
