How to remove air from engine coolant system?

There could be a few possible causes for the rear heater not blowing hot air in your 2003 Chevrolet ASTRO van. Here are a few things you could check:

1. Make sure that the rear heater control valve is fully open. This valve is located near the heater core and controls the flow of coolant to the rear heater.
2. Check the coolant level in the radiator. If the coolant level is low, the heater may not be able to produce hot air.
3. Check for any leaks in the coolant system. If the system is leaking, it may not have enough coolant to produce hot air.
4. Check the thermostat. If the thermostat is stuck closed, it may not be allowing enough coolant to flow through the system to produce hot air.

If these steps do not help, it is possible that there is a problem with the heater core itself, or with other components of the heating system. It may be necessary to have a mechanic diagnose and repair the issue.

most likely air in the colant system, an air bubble trapped when water pump was replaced. An eazy way to tell if air is in the coolant system squeze the upper radiator hose, if seems empty or can hear coolant swishing around, then there is air in the coolant system and also coolant level not compmetely topped off.

Top off coolant with Antifreeze Concentrate, NOT WATER. water will boil and evaporate, 50/50 antifreeze mix is good but if you dont know how much water has allready been added to the coolant system then straight shots of Antifreeze is recommended when toppong off coolant level.

Remove Air and Top Off Coolant

•While Engine is cool
•Remove radiator cap
•Slowly fill to the rim with Antifreeze, while at the same time squeezing the upper radiator hose to swoosh around coolant, try to get as full as you can.
•Replace Radiator Cap
•Start engine and switch air fan on high
•Remove radiator cap
•Squeez upper radiator hose and add more Antifreeze as Nessesary
•Notice preasure on the coolant hose, while adding antifreeze Concentrate preasure on the hose will stiffin up,
When coolant is full turn off the motor.

1) Coolant tank may show full but radiator is low in coolant...Cold engine...remove cap...inspect coolant level in radiator...fill if necessary,,,
2) If #1 is OK, the coolant system has an air blockage...With cold engine remove cap...Start engine...Heat control on high... when thermostat opens coolant AND air will escape from radiator...there will be coolant loss...Wait until all air escapes then carefully replace cap...When engine cools remove cap and top off coolant if required.....saailer

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What engine 2.2 or 2.4 ?
Important: On vehicles equipped with the 2.4L engine, open the coolant air bleed valve. The coolant air bleed valve is located on the top of the thermostat bypass pipe/heater pipe assembly. Close the valve once a continuous stream of coolant is expelled from the valve.
Does the cooling fan come on ?
Notice: When adding coolant, it is important that you use GM Goodwrench DEX-COOL™ coolant. If coolant other than DEX-COOL™ is added to the system, the engine coolant will require change sooner: at 50 000 km (30,000 miles) or 24 months.
Close the radiator drain ****. Remove the drain hose.
If previously removed, install the engine block drain plugs.
When installing the drain plugs, use pipe sealer GM P/N 12346004.
Important: On vehicles equipped with the 2.4L engine, open the coolant air bleed valve. The coolant air bleed valve is located on the top of the thermostat bypass pipe/heater pipe assembly. Close the valve once a continuous stream of coolant is expelled from the valve.
Fill the surge tank to the base of the filler neck.
Start the engine with the pressure cap off. Let the engine run until the upper radiator hose starts to get hot.
If the coolant level in the surge tank is low, add the proper mix of coolant until the level reaches the full cold line.
Important: After servicing the cooling system, and if the vehicle is equipped with an intermittent low coolant light, an occasional low coolant light may be encountered during some extreme driving maneuvers. This complaint should be eliminated by removing the surge tank cap and adding coolant to a level just at or above the full cold line when the system is cold.
Install the cap onto the tank with hand tight pressure.

COOLANT-ADDING ADDITIONAL
Do not remove radiator cap to add coolant to system. When adding coolant to maintain correct level, do so at coolant reserve/overflow tank. Use a 50/50 mixture of ethylene glycol antifreeze containing Alugard 340-2 y and low mineral content water.
Remove radiator cap only for testing or when refilling system after service. Removing cap unnecessarily can cause loss of coolant and allow air to enter system, which produces corrosion.

COOLANT LEVEL CHECK
The cooling system is closed and designed to maintain coolant level to top of radiator.
WARNING: DO NOT OPEN RADIATOR DRAINCOCK WITH ENGINE RUNNING OR WHILE ENGINE IS HOT AND COOLING SYSTEM IS UNDER PRESSURE.
Remove radiator cap. The coolant level should be to top of radiator. If not, and if coolant level in coolant recovery bottle is at ADD mark, check for:

• An air leak in coolant reserve/overflow tank or its hose
• An air leak in radiator filler neck
• Leak in pressure cap seal to radiator filler neck

TRANSMISSION and OIL LEVEL CHECK TUBES


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Water Pump Replacement Removal Procedure

Caution: In order to avoid being burned, do not service the engine while it is still hot. Service the engine when it is cool.

1. Drain the coolant from the radiator. Refer to Cooling System Draining and Filling .
2. Remove the air cleaner assembly. Refer to Air Cleaner Assembly Replacement in Engine Controls.
3. Remove the Mass Air Flow (MAF) sensor. Refer to Mass Airflow Sensor Replacement in Engine Controls.
4. Remove the upper fan shroud. Refer to Engine Coolant Fan Upper Shroud Replacement .
5. Remove the drive belt. Refer to Drive Belt Replacement in Engine Mechanical.
6. Remove the fan and fan blade clutch assembly. Refer to Fan Replacement .
   
   
   
7. Remove the coolant pump pulley bolts and the pulley.
   
   
   
8. Disconnect the coolant bypass hose and clamps.
9. Disconnect the radiator hoses from the coolant pump. Refer to Radiator Hose Replacement .
   
   
   
10. Remove the four coolant pump bolts.
11. Remove the coolant pump.
12. Remove the gaskets. Important: Make sure all of the gasket mating surfaces are free of burrs or other imperfections.
    
13. Inspect all of the parts. Replace the parts as necessary.

Installation Procedure

I've had this problem. 2000 GMC uses a closed coolant system. Meaning takes and returns coolant from and to the Reserve Bottle and has little air in the engine and heater systems.
If everything appears ok but no heat. "Air Lock" is the most likely cause. (With interior heater set to full heat) Solution; 1. Make sure water pump works. 2. Drain about 1/2 engine coolant into container. 3 Remove both heater hoses from engine side and flush heater core in both directs through heater hoses with garden hose. 4. Reattach heater hoses in correct locations. 4. Refill engine with coolant. 5 Start engine and run for 2 min., use caution when topping up coolant.
6. Most 2000 GMC have twist off caps with plugs located mid way on heater hoses. with engine cold, start engine these caps may be loosened to allow trapped air to escape. Do not attempt with engine hot due to hot coolant injuries. This may take more than one attempt to remove all air from heat system. 7. Lastly most 2000 GMC water pumps have a bleeder plug,( 3/8" square driver plug) located on the water pump. With egine cold this plug should be removed to remove any air. Reinstall plug with thread sealant.
Hope this helps cheers

BLEED AIR OUT COOLANT SYSTEM.WAIT UNTIL ENGINE COOL DOWN.REMOVE COOLANT OVER FLOW PRESSURE CAP.IF YOU HAVE 3.1 OR 3.4 ENGINE OPEN AIR BLEED SCREW ON WATER PUMP BYPASS HOSE.OPEN BLEED SCREW.WATCH COOLANT IN OVER FLOW AS YOU OPEN BLEED SCREW COOLANT WILL DROP IN OVER FLOW JUG. AS IT DROPS CLOSE BLEED SCREW ADD MORE COOLANT IN OVER FLOW JUG DO THIS UNTIL COOLANT LEVEL STAY AT COLD FULL MARK.WHEN DONE TIGHTEN BLEED SCREW DONT OVER TIGHTEN IT OR IT WILL STRIP OUT BREAK.CRANK CAR UP UNTIL THERMOSTAT OPEN THAT WHEN TOP RADIATOR HOSE GET HOT.WATCH COOLANT GAUGE,IF ENGINE TEMPERATURE RISES TURN OFF ENGINE WAIT UNTIL COOL.REMOVE RADIATOR PRESSURE CAP USING A RAG TO KEEP FROM GETTING HANDS SCALED.ADD MORE COOLANT IF NEEDED WHEN ENGINE COOLANT STOP DROPPING IN OVER FLOW JUG AND ENGINE DONT OVER HEAT AIR IS OUT OF COOLANT SYSTEM.

how did you change the coolant? did you remove a hose or just open up the valve at the bottom of the radiator

If you removed the lower radiator hose then you may have induced air into the cooling system

when the engine is cool, remove the coolant cap and start the engine

wait until you have a good flow of coolant out of the reservoir to ensure you have all the air out of the system

I Suspect that you have AIR in your COOLING SYSTEM Fallow Procedures BELOW to Insure there is NO AIR IN COOLING SYSTEM


Draining and Filling Cooling System

Draining Procedure

Important: Do NOT add any engine coolant supplement sealant pellets to the cooling system. Drain and refill the engine cooling system every 5 years or 240,000 km, (150,000 mi) , whichever occurs first.

1. Park the vehicle on a level surface.
2. Remove and clean the coolant recovery reservoir.

Caution: Refer to Radiator Cap Removal Caution in Service Precautions.

1. Remove the radiator cap when the engine is cool:

3.1. Slowly rotate the cap counterclockwise to the detention tab. Do not press down while rotating pressure cap. 3.2. Wait until any residual pressure, indicated by a hissing sound, is relieved. 3.3. After all hissing stops, press down on the radiator cap and rotate the cap counterclockwise in order to remove the cap.
Important: Recover and store used coolant in a used coolant holding tank and submit the used coolant for recycling on a regular basis. Do NOT pour used coolant down the drain. Ethylene glycol antifreeze is very toxic. Disposing of ethylene glycol into the sewer system or ground water is both illegal and ecologically unsound.

1. Place a drain pan under the radiator drain valve in order to collect all of the used coolant.
2. Open the radiator drain valve located at the bottom of the radiator tank. If only partial cooling system draining is required, drain enough coolant to perform the procedure.
3. Open the air bleed valve on the thermostat housing 2 full turns
   1. Open the air bleed valve above coolant pump 2 full turns.
   2. Place a drain pan under the engine block drains in order to collect the used coolant.Important: Allow the coolant to drain completely.
      
      
      1. Remove both of the engine block drains.
      • The front left engine block drain is located between the starter motor and the engine oil filter.
      • The rear right engine block drain is located near the crankshaft position sensor.
      Filling Procedure
      Reinstall the engine block drains
      
   3. Close the radiator drain valve,
      1. Install the coolant recovery reservoir. Notice: When adding coolant, it is important that you use GM Goodwrench DEX-COOL or HAVOLINE DEX-COOL coolant. If Coolant other than DEX-COOL or HAVOLINE DEX-COOL is added to the system the engine coolant will require change sooner; at 50,000 km (30,000 mi) or 24 months.
      2. Slowly add a 50/50 mixture of GM Goodwrench DEX-COOL or HAVOLINE DEX-COOL and clean, drinkable water to the radiator until the coolant level is at the base of the radiator fill neck.
      3. Wait for 2 minutes and reinspect the level of the coolant in the radiator. If necessary, add coolant to the radiator until the coolant level is at the base of the radiator fill neck.
      4. Install the radiator cap.Ensure that the radiator cap arrow points toward the radiator overflow tubeImportant: The air bleed valves are brass. Do NOT over-tighten the air bleed valves.
         
         
         1. Close the air bleed valve above the coolant pump.
            1. Close the air bleed valve on the thermostat housing.
            2. Fill the coolant reservoir with a 50/50 mixture of GM Goodwrench DEX-COOL or HAVOLINE DEX-COOL and clean, drinkable water. Caution: Refer to Radiator Cap Removal Caution in Service Precautions. Important: If the coolant temperature indicator turns ON, turn the engine OFF immediately and allow the engine to cool. Do NOT remove the radiator cap.
            3. Start the engine and allow the engine cooling fan to cycle on and off 3 times. If the low coolant indicator does not turn OFF and the coolant level is above the Full Cold mark on the coolant recovery reservoir, refer to Engine Coolant Temperature Gage Inaccurate or Inoperative.
            4. Turn off the ignition.
            5. Allow the engine to cool.
            6. Ensure that the engine coolant concentration is sufficient.