OK, before anything, i would like to say that I have searched and nothing that I have looked at seems to be helping. ALSO the car is STOCK!!!!
THE SYMPTOMS: CAR only overheats when i am on the freeway. If I am driving on the street or just sitting there it is cool but once i hit the freeway it overheats.

WHAT I DONE SO FAR: I have changed the water pump, thermostat, radiator, hoses,and burped/bled the cooling system. I have also taken it to a mechanic and he says that everything is fine. The only thing that i can think of is the head gasket
but the mechanic said he did the compression test and everything is fine.

MY QUESTION: If the head gasket is messed up would I see a the oil milky?
OR does that only happen when the head gasket is
messed up by the cylinders? AND can the head gasket be making
my car overheat without losing compression / oil and coolant
not mixing together?

THANKS.................

 

When the engine overheats, does the radiator fan run continously?

 

Not to sure can't really hear the fan on the freeway. But when i am still or driving on the street it goes on continously.

 

Is the radiator cap bad?

 

yeah the cap is new. came with the new radiator.

 

Check radiator cap, check fan switch, make sure fan turns manually, check fan fuse. Do the rad. hoses feel hard as a rock after driving for 20 min? if so you may have a leak in the head gasket between a cylinder and a cooling jacket. Also if your radiator is clogged even 30% it will not sufficiently flow fluid. A stuck thermostat or air pocket in the heater core can cause overheating as well. I would assume a headgasket problem if it only happens when your driving, becasue with the engine under load it would leak alot of pressure into the cooling sytem, other than that I's say the next best thing to check is your fan.

 

Does it hesitate to start in the morning and run rough for a few seconds? Also any smoke out the exhaust? You could also just be low on coolant. When you bleed the system you need to run the heater on full blast on fresh mode while you fill the radiator, to bled the air out of the heater core. Basically if you have a blown head gasket though you will notice your radiator hoses being rock hard after about 20 min. of driving.

 

there is no smoke coming out of the exhuast. But I got to check if the hoses get hard. If I had a leak between the cylinder and the cooling jacket wouldn't I see my oil all milky and stuff? If so I dont have that and this overheating has been going on for a long time now. New radiator, thermostat, water pump, radiator cap, new hoses. If the head gasket is leaking between the cooling jacket and the outer part of the block (not the cylinders) that would cause my car to overheat right?