Just wondering if anyone has any suggestions, I have been in battle with my truck for about a month now, I can drive for about 30 to 45 minutes with AC on before it will get hot but once it does it really does, I can turn heater on full and it will gradually go down, I have replaced the radiator, fan, fan clutch, thermostat, hoses, water pump, belt, Coolant temperature sensor, degas bottle and cap, I am running out of things to replace.......I do not have any water in my oil, so I do not believe i have any bad gaskets that I know of, and I do have all factory shrouds and plastic in place....any ideas would be greatly appreciated...........203,000 miles running strong but hot !!!

 

I'd recommend a hydrocarbon test on your coolant to rule out gasket issues.

 

does it overheat without the A/C on?

 

Yes it does overheat w/o AC, just takes a little longer, and it only overheats at highway speeds or when I have driven for a while on a pretty warm day, if it is cool like mornings and so on it never overheats.

 

other than my now infamous overheating issue my 4.2 has been a beast, 203,000 on odometer and the only thing I have broken is a CV shaft in a 4ft muddhole..lol

 

Maybe there is a big air pocket\bubble some where in the radiator hose?

 

Not sure I have had hoses and radiator off twice now, and still the same thing each time back together. Going to start small again replace thermostat in case maybe defective and go from there again, I am not a pro but i thought I knew enough not to get this stumped........Thanks for all the input!!

 

If you have your hose off to the waterpump try shining your flash light in there to see if the impeller is ok.

 

Pump is brand new but good idea weirder things have happened......Thanks

 

did you put the thermostat in backwards? the genius (dad) who did mine put it in backwards and it only overheated on the highway

 

Placed it in spring towards motor and referenced manual to make sure, almost positive it's correct.

 

that rules that out then

 

Brakes dragging putting extra load on the motor?

Cracked head letting hot gasses heat up the water?

 

Do you have an automatic trans with the internal trans cooler in the radiator? Could be the trans is heating the coolant. (That's a guess, of course!)

 

Have thought about tranny, need to take it to the shop and see what they think...thanks