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Replaced water pump, thermostat, fan clutch, radiator seems to be in good condition, yet still overheating. 1986

F-150 302 CID

Is it boiling over or is it just a high gauge reading. If it is just the gauge reading, get the radiator temp checked with a non-contact thermometer. If it is boiling or pushing coolant out get a pressure test done on the cooling system.It is hard to be more specific with the scant information you have given. Also check the engine timing.

It’s not boiling over, just a high gauge reading. I have noticed that when it gets hot, the upper radiator hose gets hot, (which is normal) but the lower hose does not, nor does the radiator cap.

That sounds like the gauge sensor.

The upper hose should get hotter than the lower hose. The difference is the heat that’s disspated by the radiator.

On a 1986 there are a number of possibilities. While your radiator may appear to be in good condition, its core could be coated with residue that’s preventing it from properly disspating heat, perhaps even with some tubes plugged. This can be checked by looking for cool spots with a pyrometer.

Sometimes the inner linings of old hoses can collapse and the hoses look perfect from the outside. On a 24 year young vehicle I’d definitely consider new hoses.

You don’t mention having tested the T-stat. If it’s the original, I’d replace it. I might bench test it afterwards just as a curiosity.

Have you checked the areas in front of the radiator for clogging with debris? If you have AC, the AC condensor could be blocked and restricting airflow also.

You didn’t mention any other signs, so can I safely assume that you looked and saw nothing that would suggest a headgasket?