2000 Chevy Silverado Airlocked?

Tiny
KEVVY
  • MEMBER
  • 2000 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 201,500 MILES
A week ago I had opened the surge tank cap while the engine was warm and there was a bit of vacuum. Since then my engine temp is running fine but my heat is not very warm inside the truck. My truck has always heated fine until I did this so I assume my cooling system is air locked. If this is the case, how can I purge the air out?
Friday, February 26th, 2010 AT 9:08 AM

7 Replies

Tiny
SCOTTY DEE
  • MECHANIC
  • 592 POSTS
Opening the degas bottle shouldn't cause an issue. If you are suspect to air in the cooling system, you can bleed the air by removing the radiator cap, and let it come up to temperature. How long has it been since the coolant was exchanged?
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Friday, February 26th, 2010 AT 1:58 PM
Tiny
KEVVY
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  • 4 POSTS
I took the shrowd off to look at the radiator. There is no cap, the only cap is on the surge tank. The day before I took the cap off my heat was just fine so it is not the coolant. There was a lot of vacuum in the tank when I took the cap off. My truck temp is running consistent a 190 degrees and all seems well. Both hoses coming from the heater core are warm so it is not plugged. I know there is air in it and don't know how to bleed it out.
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Friday, February 26th, 2010 AT 2:13 PM
Tiny
SCOTTY DEE
  • MECHANIC
  • 592 POSTS
WTF am I thinking? Start the engine.
Idle the engine for 1 minute.
Loosely install the surge tank cap. Do not allow the system to build pressure.
Cycle the engine from idle to 3000 RPM in 30 seconds intervals until the engine coolant reaches 99 °C (210 °F) and the thermostat opens.
Shut off the engine.
Refer to step 3 in order to remove the radiator surge tank cap.
Start the engine.
Idle the engine for 1 minute. Fill the surge tank to 1/2 inch above the COLD FULL mark on the radiator surge tank.
Install the radiator surge tank cap.
Cycle the RPM. Idle the engine to 3000 in 30 second intervals until the engine coolant reaches 99 °C (210 °F).
Shut off the engine.
Top off the coolant, as necessary, to 1/2 inch above FULL COLD mark on the radiator surge tank.
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Friday, February 26th, 2010 AT 2:22 PM
Tiny
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Done that. I even parked it with the front up in a snow bank so the air would work it's way out. Thanks for the suggestions.
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Friday, February 26th, 2010 AT 2:33 PM
Tiny
SCOTTY DEE
  • MECHANIC
  • 592 POSTS
Okay then, we can rule that out. The next step is to determine if the blend door is in the right position. Under the evap case, you can access the blend door. Move the temperature settings from cold to hot and see if the door is opening all the way, and closing all the way.
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Friday, February 26th, 2010 AT 2:42 PM
Tiny
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OK, where is the evap case.
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Friday, February 26th, 2010 AT 2:47 PM
Tiny
SCOTTY DEE
  • MECHANIC
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On the passenger side under the dash. You'll see what I'm talking about when you start exploring.
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Friday, February 26th, 2010 AT 4:17 PM

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