I have an 02 Ram 1500 with a 4.7l and I’ve replaced the thermostat and bled the cooling system yet when I’m on the freeway (I have a 45 minute commute to work) after about 20-25 minutes the truck will start to run hot and the needle will start to creep above half way but when I turn the heater on the temp goes down. And when I get to town and drive through town the temp is fine and doesn’t get hot. And obviously when I run the a/c it run pretty hot. And when on the freeway and I don’t turn the heater on if I let off the gas for a few seconds the needle will slightly go down as well. Do I still have air in the system? And should I bleed it at the air screw or take off the radiator/ resivoir cap and turn the heater on and run it until it gets to operating temp then top it off and out the cap back on?

 

Yes, I would bleed it again. The 4.7's do not like to be overheated, so find the issue quickly.

 

Should I bleed it by via the bleeder screw or like this
1-remove the radiator/reservoir cap when the engine is cold
2-start the engine and let idle
3-turn the heater on max
4-keep coolant on hand and add it as needed
5-some coolant may gush out with the air
6-keep doing this until the engine is at operating temperature and the heater is hot
7-after the coolant settles down and the engine is warm,,install the cap
This may take as long as 20-30 minutes

ive been told by multiple people to bleed it at the air screw and not the other way and then I’ve been told the opposite and not use the bleed screw

 

I thought the bleeder bolt was the only way to get all of the air out of the system, and that is why it's there. I'm referring to the 8mm hex bolt.
What happened to get you to replace the coolant? Was this regular maintenance or did you have a temp problem? I ask because if you had a temp problem originally then your current overheating problem may have nothing to do with air in the system.

 

According to the factory service manual, that's the whole point of the expansion tank. There is no factory bleed procedure:

 

I bought it back in august and added coolant to it cuz the tank was empty, and For a day or 2 it still was running hot, so I replaced the thermostat and coolant. I tried bleeding it at the 8mm hex bleeder screw and it still runs a little above half before I turn the heat on. So idk if I got a faulty thermostat or if there’s just trapped air still in the system. At first I thought it could be the coolant temp sensor. But then thought otherwise. The puzzling part for me is that it runs warm/hot on the freeway at speed, but if I hit traffic the temp goes down or if I drive through town the temp never gets above halfway

 

so should I pop the cap off while running it and try bleeding it that way?

 

You may have a clogged radiator.
A couple of things you could try:
- drain the radiator. See if the coolant is discolored.
- With radiator drained, remove the lower radiator hose and check the hose and bottom radiator port.
- With empty radiator, run water into the filler neck and see if it comes out the bottom as fast as you are putting it in, or if there is restriction.
If you detect a clog, I prefer to replace the radiator, but some have had luck with the flushes.
Also inspect the radiator for leaks, see if you can find any bulges in the fins. Any white dried coolant on the engine?

 

Before I changed the thermostat I added new coolant and did a coolant flush and it didn’t seem to have a clog, and the coolant wasn’t discolored after running it for a few days. but I can definitely do it again.

 

Before I changed the thermostat I added new coolant and did a coolant flush and it didn’t seem to have a clog, and the coolant wasn’t discolored after running it for a few days. but I can definitely do it again. and I haven’t seen any bulges in the fins or any white dried coolant.