Hey ya’ll, I’ve got a question about my 92 ford f150 4.9 inline 6. So firstly, the reservoir for the coolant seems to mysteriously dry up. There are no leaks and I’ve refilled it 3 times now. Its not like something that is every 20 miles, it takes a while to empty. Also, my engine is getting hot, sometimes really hot. But it usually maintains at an average to slightly high temperature because every time you hit the gas and accelerate, the temp drops rapidly. There is no strong patterns to if it overheats on the highway or in town, but usually after about an hour, she pretty much purrs at medium-high to high temps when going slow in town and not accelerating on the highway. Also, I don’t know if this is relevant but the oil pressure gauge responds directly with the temp gauge. temp gets hotter, oil goes higher pressure and vice versa. My crude knowledge has led me to believe it could be the water pump or a leak in the coolant system. Also, I’m worried the higher operating temps could have messed up the head gasket. The previous owner did pull a car trailer with far too much weight for the mazdog 5 speed…
You do have a leak. If nothing is hitting the ground, then it may be internal. If your truck has the plastic intake, the coolant passages through it are known to fail and can leak into the engine block. check your oil for signs of moisture. Moisture in oil takes on a ‘coffee creamer’ look to it. You could also have a weak water pump or lazy thermostat. A cooling system pressure test can confirm even a small leak. If you’re worried about a blown head gasket, a cylinder leak down test and a coolant hydrocarbon test can determine if there may be a problem.if the coolant tests and leak down tests show no problems, I’d flush the cooling system and change the water pump, thermostat, and radiator cap and have the radiator flow-checked.
"Also, I’m worried the higher operating temps could have messed up the head gasket. "
I think a head gasket leak is the original cause of your overheating.