2001 mustang gt overheating

[orinsmiley11]

Few months ago my intake manifold broke on one of the small coolant lines and sprayed coolant everywhere. I then replaced it and noticed my car overheats. I then replaced the radiator with a 3 core and put all new coolant and a new thermostat. Week goes by and I was still over heating. Replaced the water pump, still overheating, did thermostat with a motorcraft stock thermostat. It helped when moving, but when I sit at idle it still gets 230+ after a short time. When I did the water pump I didn't notice any debris or dried coolant. Theirs pressure in the reservoir and no bubbles in hose that im aware of. And if it did have any they should have been surculated by now. My car really over heats when the ac is on, even while moving it gets very high in temps. What are my next steps in terms of solving this problem?

 

[Noobz347]

It sounds to me like you have air still trapped in the cooling system.


Look this procedure over and see if you missed any portion:

Step-by-Step Procedure:​

1. Car Cool & Safely Supported:
   
   • Make sure engine is completely cold.
   • Raise the front of the car on ramps or with jack stands if possible. This helps air rise to the degas (coolant reservoir) tank.
2. Set Climate Controls:
   
   • Turn the heater to full hot with the blower off or low. This opens the heater core circuit.
3. Remove Degas Bottle Cap:
   
   • Open the coolant reservoir cap (it's not a pressurized radiator cap system — the pressure comes from this cap).
   • Insert a spill-free funnel if you have one. Otherwise, just fill carefully.
4. Slow Fill with 50/50 Coolant:
   
   • Fill the degas bottle slowly until it reaches the “Full Cold” line or starts backing up in the funnel.
5. Squeeze Upper Radiator Hose:
   
   • Do this several times to purge trapped air. You may see bubbles in the reservoir.
6. Start the Engine:
   
   • Let it idle with the cap off.
   • Keep an eye on coolant level. It will likely drop — top it off as needed.
   • Watch for large air burps and bubble activity.
7. Monitor Temperature and Thermostat:
   
   • As the engine reaches ~190–200°F, the thermostat will open. You’ll see a more rapid drop in coolant level.
   • Add more coolant to keep it at or above the “Full Cold” line.
8. Rev Occasionally:
   
   • Blip the throttle to ~2000–2500 RPM for 5–10 seconds a few times to move coolant through the system.
9. Run Until Fans Cycle:
   
   • Allow the engine to reach operating temperature until the cooling fan kicks on and off at least once.
   • That confirms full circulation through the radiator.
10. Top Off and Cap It:
    
    • Once bubbling stops and the level stabilizes, cap the reservoir with the factory cap.
    • Let it idle a few minutes more to verify stability.
11. Cool Down & Recheck:
    
    • After the engine cools fully (several hours or next morning), check and top off the degas bottle again to the “Full Cold” line.

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Optional — Second Burp:​

Drive the car around the block after the first cycle and let it cool. Then repeat steps 1–5 for a final check. Some air pockets work themselves out after driving.