July 19, 2009My dad just got a 2004 explorer with the 4.0L SOHC motor, 88K Miles, and it has been overheating on him. The oil does not have any coolant in it, however the area on top of the engine between the heads, below the plastic upper intake assembly, has a darker fluid there. It seems to be losing coolant, however I have yet to see the overheating condition.
Does the pressurized reservoir cooling setup have a pressure relief system, and if so where does it discharge?
He purchased this car from an auction through a friend. He made a couple 80 mile road trips since the purchase and had no overheating issues. The cooling system reservoir doesn't seem to have the brown residue inside it that I have seen more associated w/ a blown head gasket.