[Squints]

It only does it when after it's been sitting for a long time. I.E. it only does it on my way to work in the morning, and on my way home from work in the afternoon. And, it will only do it once. The heat in the car will go cold too. I pull over, relieve the pressure by opening the cap on the reservoir slightly. When the coolant gets to the top, I shut it and let the level go back down. Then, I'll do it a few more times until all of the pressure it released. the top hose (from the block to the top of the radiator) will be cold, like there's nothing running through it. It will also be tight, like there's a ton of pressure in it. Once the pressure from the system has been release via the reservoir cap, i can squeeze the hose and hear the coolant flowing through the radiator and see it rise in the res. After I do this, it's fine for as long as I'm going where I'm going. The heat also comes back on and blows really hot, like it's supposed to.

I replaced the thermostat, have had two different shops look at it. Both did a pressure test and it was fine. Both recommended replacing the thermo, which was already done. The one i put in doesn't have a vent hole. I'm going to take it off and drill one. But, it was doing the exact same thing before I replaced it. So, I'm guessing that was not the issue. Of course, I could have gotten a bad, new one. Always possible. But, this is driving me freaking nuts.

I'm thinking it has air in the system. But I've burped it several times. Maybe I should do a fluch and fill. that's the only thing I haven't tried.

Any suggestions?

BTW, it's a 5.4L Triton

[Lefty]

Try to reburp the system of air. It took me well over an hour, with the front of the car raised to burp my Cobra. Sometimes it just takes a while to flush all the air out.

[Squints]

i tried that. but i didn't do it for an hour. it's in the shop for another issue (misfire, needed 2 coils and all new plugs.) but i told them to look at the overheating issue and they couldn't get it to do it. they wanted to keep it over night so they could crank it up totally cold with everything settled and drive it around to see what happens. hopefully it's something as simple as air in the system.

[Lefty]

Keep us posted

[TaintedStang]

I had a problem exactly like yours with my first truck. It was a 99 ranger with the 3.0v6. My water pump went out and after installing the new one I had so much air trapped in the cooling system that air pocket's would build up right above the thermostat and prevent it from opening and the truck would run hot but if I slowly removed the radiator cap it would release pressure and the thermostat would then open. I literrally spent 4 hours and a half tank of gas with my truck backed down into a ditch trying to burp the cooling system. It never would fully rid the air. I finally got frustrated and just took the thermostat out and drove it for over a year without one. When I finally reinstalled the new one I guess the system had rid itself of any air.

[Squints]

that's exactly what it's doing, i think. same symptoms.

the guys at the shop told me that the radiator was clogged. outside, not in. said it wasn't allowing enough air to flow over it to effectively cool the fluid running through it. they seemed butt hurt when i told them that if that was the case, it would constantly overheat. my issue is that it will only overheat ONE TIME and then after i release the pressure and the thermostat opens, it's fine. i drove for over 2 hours the other day after it happened and it was perfectly fine. but they were insistent that it wasn't cooling the fluid due to a bad radiator. then, suggested that i replace the radiator AND water pump. i can understand doing that if it's needed and the symptoms point to that. but it just isn't logical that the radiator is screwed up when i t seems to run absolutely perfect after the pressure gets released from the system.

it's so fucking frustrating when people won't listen to you, and take what you know about you own fucking car, into account. i'm not spending 500 bucks, parts and labor on a radiator and water pump because you THINK that's the issue and it doesn't even make sense.

[TaintedStang]

Originally Posted by Squints that's exactly what it's doing, i think. same symptoms. the guys at the shop told me that the radiator was clogged. outside, not in. said it wasn't allowing enough air to flow over it to effectively cool the fluid running through it. they seemed butt hurt when i told them that if that was the case, it would constantly overheat. my issue is that it will only overheat ONE TIME and then after i release the pressure and the thermostat opens, it's fine. i drove for over 2 hours the other day after it happened and it was perfectly fine. but they were insistent that it wasn't cooling the fluid due to a bad radiator. then, suggested that i replace the radiator AND water pump. i can understand doing that if it's needed and the symptoms point to that. but it just isn't logical that the radiator is screwed up when i t seems to run absolutely perfect after the pressure gets released from the system. it's so fucking frustrating when people won't listen to you, and take what you know about you own fucking car, into account. i'm not spending 500 bucks, parts and labor on a radiator and water pump because you THINK that's the issue and it doesn't even make sense.

I know your pain man. I had the run around with mechanics also. All I can really tell you is to keep burping the cooling system or remove the thermostat and run it like that for a litle while. Just keep an eye on your coolant level since it will get lower as the air get's burped from the system. Good luck.

[Squints]

yeah, i think i'm gonna take it out tomorrow and run it without for a few days and see how it acts.