2002 Ford Explorer 4.0 V6 Oberheating issue

[Socc91]

I have a 2002 Ford explorer and am having an overhesting issue. First i had a hose that cracked and started leaking so i replaced it (first sign of something wrong to come). I noticed sfter that the car would hear up to normal temperature in normal amount of time but i would still have no heat. After about 20min of driving i would have hot heat. After 30-40 min of driving my idle rpms would start to increase to about 1700. Around 40+ min is when the car begins to overheat and i need to blast the heat to prevent temp from going too high. I have since replaced the thermostat and flushed the system, still having same issues. I dont want to start guessing on parts to find this problem. I assume it culd be anywhere from radiator, heater core, water pump, clutchfan or even a crack in the i take manifold (although i see no leaks anywhere). Anyone have any suggestions?

 

[fordbluefamily]

How long/how far have you driven while it was running hotter than normal?

 

[Socc91]

Maybe 30 minutes. And this is in new york where it is doing this when it is 30 degrees out

 

[fordbluefamily]

External temps don't really matter when you are low on coolant. There is no way for the engine to exchange the heat with that cold air if the coolant isn't flowing. These engines do not tolerate overheating very well let alone driving while that way. Check thermostat (I would go motorcraft here as cheap ones can be an issue) clutch fan, easy to check this, and search here for how to adequately burp these engines. If all of that is good, start looking for leaky head gaskets. There is no coolant in the intakes of these. No crossover like the v8. It is all in the heads. FWIW, I just changed my 04 engine this summer that was overheated way less than yours. It has warped heads. Does your coolant tank overflow?

 

[Socc91]

Tank doesnt overflow but builds up alot of pressure which i assume is normal for this type of cooling system. When i shut the car off after heating up i do here gurgling and bubbling coming from thermostat housing. I have burped the system before still same results. Since i do actually get hot heat after a while is there anything that you would eliminate? Would heatercore or radiator be fine since i do get hot heat eventually?

 

[fordbluefamily]

That sounds bad. A lot of pressure is bad. 16psi is normal. Might be time to sniff the coolant tank for combution using a chemical tester. Next I would pressure check the cooling system using a gauge. See if it bleeds off.