94mustang94

it started doing this out of nowere. and i really don't think the high fan is coming on. would i have to change the whole black box to fix the fan part?

mjr46

thing is......if it overheats/ runs hot going down the road.....you shouldn't need the high speed fan cause air flow across the radiator in terms of cfm is greater than any fan that you could have up there so air at cruise should do the job, if not the prob is not a fan issue, I'd look at radiator and or cap and or t-stat, if all that is good, do a block check and check for a blown head gasket

94mustang94

well i don't think it is a head gasket beacuse i just recently changed my oil and there was nothing milky about it. how could a cap raise the boiling point?

mjr46

as a liquid is heated it expands, since a cooling system is a sealed system once the coolant is heated to the point where it as expanded and and raised presure in the system to 16 psi the cap pops open and releaves pressure and excess goes into overflow bottle, if the cap is bad and does not relieve pressure it will continue to build pressure and superheat and under extreme conditions exentually it can rupture weak points in the system, such as hoses...FYI, blown head gaskets don't always manifest themselves as choclate milkshake in the oil....pending where they blow such as around the firing ring, it'll push hot exhaust gases into cooling system and superheat coolant that way, a block check kit will reveal hydrocarbons/ exhaust gases in the coolant thus indicating a blown head gasket