1997 Ford Truck overheating

Test the thermostat and then comeback-You sure its not an airlock problem

flushed system, changed thermostat, serpentine belt, idler pully. think it is airlocked, but ran for 2 hours without cap on, now drops to cold for 1-2 miles but no overheat.

now drops to cold for 1-2 miles but no overheat.

Are you refering this to the engine temperature gauge or the temperature inside the vehicle

both. when temp gauge drops, so does the heat in cab. thats what makes me think its an air pocket. but i also have to add about a gallon antifreeze everyday.????? it is not going into oil and doesnt leak since i changed radiator cap????

also getting a chatter noise when engine is under light load and very small swirling motion of coolant in fill tank when engine running. could there possibly be a problem with water pump??? would think it would overheat all the time then.

now drops to cold for 1-2 miles but no overheat.

You're losing coolant somewhere is there any physical leak-if not your burning it in the combustion chamber-do you have white smoke coming out of the exhaust.

Pull the thermostat out and re-observe if its still doing the same thing.

One way to test for a bad water pump is to squeeze the upper radiator hose when the engine is hot and idling. Careful, because the hose will be HOT! If you do not feel much coolant circulating through the hose when you rev the engine, the pump may be bad. The other cause might be a bad thermostat that is not opening properly (remove and inspect the thermostat), or a clogged radiator

dont see any physical leak, have white smoke until engine gets to running temp, then goes away. i have checked the top hose. it gets warm but not hot. squeezes easily until thermostat opens, then can feel coolant going through but doesnt seem like alot of pressure, but didnt try it while revving engine. could be clogged radiator. when first happened, opened cap and found rust colored foamy stuff, thats why i flushed and changed thermostat.

Feel across the radiator do you feel cold spots-- if so its clogged-up the temperature should be even right across.

ok will have to pull all the cowling. the only open spot is the fan opening

thank you for all your help