Overheating, air in the cooling system

Hi Terry:

Yes, an air block can cause loss of heat, overheating.

Here are the directions for refilling the cooling system:

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Filling Procedure

Notice: The procedure below must be followed. Improper coolant level could result in a low or high coolant level condition, causing engine damage.

Notice: Refer to Fastener Notice (See: Vehicle > Vehicle Damage Warnings > Fastener Notice).

1. Close the radiator drain cock.

Tighten the radiator drain cock to 2 N.M (18 lb in).

2. If the engine block drain plug was removed, perform the following:

1. Apply pipe sealer to the drain plugs.
2. Install the drain plugs.

Tighten the drain plug to 22 N.M (16 lb ft).

3. Lower the vehicle.

Important: Use a 50/50 mixture of DEX-COOL antifreeze and clean, drinkable water.

4. Slowly fill the cooling system with a 50/50 coolant mixture. Refer to Approximate Fluid Capacities (See: Maintenance > Service Intervals).
5. Install the coolant pressure cap.
6. Start the engine.
7. Run the engine at 2,000-2,500 RPM until the engine reaches normal operating temperature.
8. Allow the engine to idle for 3 minutes.
9. Shut the engine OFF.
10. Allow the engine to cool.
11. Top off the coolant as necessary.
12. Inspect the concentration of the engine coolant, using the J 26568.
13. Rinse away any excess coolant from the engine and the engine compartment.

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Let me know if this helps or if you have other questions.

Take care,

Joe

Welcome back:
If there is a bleeder, that is correct. Open it while filling the system. When a steady stream of coolant starts to leak from it, it should be bleed.

Let me know if that helps.

Joe

Hi and thanks for using 2CarPros.

Refilling the system is straight forward. However, there is a bleeder that needs opened when you fill the system.

Here are the directions for refilling and bleeding the system. It starts with number 4 because the previous numbers are not relevant for the refilling process.

Notice: When adding coolant, it is important that you use GM Goodwrench DEX-COOL (R) or HAVOLINE (R) DEX-COOL (R) coolant. If Coolant other than DEX-COOL (R) or HAVOLINE (R) DEX-COOL (R) is added to the system the engine coolant will require change sooner-at 50 000 km (30,000 mi) or 24 months.

4. Slowly add a 50/50 mixture of GM Goodwrench DEX-COOL (R) or HAVOLINE (R) DEX-COOL (R) and clean, drinkable water to the radiator until the coolant level is at the base of the radiator fill neck.
5. Wait for two minutes and recheck the level of the coolant in the radiator. If necessary, add coolant to radiator until the coolant level is at the base of the radiator fill neck.

Picture 1

6. Install the radiator cap.

Picture 2

7. Ensure that the radiator cap arrow points toward the radiator overflow tube.

Important: The air bleed valves are brass. Do NOT over-tighten the air bleed valves.

Picture 3

8. Close the air bleed valve above coolant pump.

Picture 4

9. Close the air bleed valve on the thermostat housing.
10. Fill the coolant reservoir with a 50/50 mixture of GM Goodwrench DEX-COOL (R) or HALVOLINE (R) DEX-COOL (R) and clean, drinkable water.

Caution: Do not remove the radiator cap while the cooling system is hot. Serious personal injury may result. Only remove the radiator cap from a cool engine.

Important: If coolant temperature indicator comes on. Turn the engine OFF immediately and allow the engine to cool. Do NOT remove the radiator cap.

11. Start the engine and allow the engine cooling fan to cycle on and off three 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 LOW COOLANT LEVEL Message Always On in Instrument Panel, Gauges and Warning Indicators.
12. Turn the ignition off.
13. Allow the engine to cool.
14. Ensure that the engine coolant concentration (freeze point) is sufficient. Refer to Coolant Concentration Testing.

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As far as the heat, allow the engine to warm up fully with the heater on high. Feel both heater core hoses. Both should be hot. If only one is hot, the heater core is plugged. If both are hot, you are correct with the blend air door actuator.

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Let me know if this helps or if you have other questions. One more thought. Make sure the lower radiator hoses isn't collapsing when the overheating takes place. If it is worn and doesn't have a spring in it to prevent it from collapsing, higher RPM's can cause a problem. Hence, it overheats at higher speeds. It's just a thought.

Let me know,

Joe

Did you replace the thermostat? If so, are you certain it wasn't put in upside down? It sounds like something is blocking the system.

Terry:
The sad part is if the thermostat needs replaced, you need to go through this all over again. Honestly, the bleeding process (bleeder) should have been opened when it was first being refilled. I wonder if that is why there is air blocked in places that are stubborn to get. Honestly, it may be time to replace the thermostat. It may be sticking or not fully opening.

Regardless, here are the directions for replacing the thermostat. I figured I would include them. The attached pictures correlate with these directions.

THERMOSTAT REPLACEMENT
Removal Procedure

Picture 1

1. Remove the air cleaner and duct assembly. Refer to Air Filter Element Replacement in Computers and Controls.
2. Drain the coolant until the coolant level is below the thermostat. Refer to Draining and Filling Cooling System.
3. Remove the radiator hose from the thermostat housing. Refer to Radiator Hose Replacement - Inlet.
4. Remove the thermostat housing bolts and clean any sealer from the bolt threads.
5. Remove the thermostat housing and gasket.

Picture 2

6. Remove the thermostat.
7. Clean the mating surfaces.

Installation Procedure

Picture 3

1. Install the thermostat.

Picture 4

2. Install the thermostat housing and gasket.
3. Install RTV sealer (GM P/N 1052366 or the equivalent) to the thermostat housing bolt threads.

Notice: Refer to Fastener Notice in Service Precautions.

Picture 5

4. Install the thermostat housing bolts.
Tighten the bolts to 25 Nm (18 ft. Lbs.).
5. Install the radiator hose to the thermostat housing. Refer to Radiator Hose Replacement - Inlet.
6. Install the air cleaner and duct assembly. Refer to Air Filter Element Replacement in Computers and Controls.
7. Fill the cooling system. Refer to Draining and Filling Cooling System.
8. Inspect the cooling system for leaks. Repair as necessary.

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Also, here are the directions for replacing the mode door actuator so you can control air flow. The attached pics correlate with these directions

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MODE ACTUATOR REPLACEMENT
REMOVAL PROCEDURE

Picture 6
1. Remove the left instrument panel insulator.
2. Remove the knee bolster from the instrument panel.
3. Disconnect the vacuum lines from the mode valve vacuum actuator.
4. Cut the tie strap (1) that is on the back side of the mode valve vacuum actuator.

Picture 7

5. Lift to release the mode vacuum actuator retaining tab and just begin to slide the vacuum actuator toward the steering column.
6. Rotate the mode valve lever fully forward (counterclockwise) and hold in place until instructed.
7. Carefully rotate the vacuum actuator toward the front of the vehicle until the actuator is released from the mounting pins on the HVAC module case.

Picture 8

8. Extend the vacuum actuator below the HVAC module case mounting pins, then slide the vacuum actuator rearward in vehicle, past the pins.
9. Disconnect the vacuum actuator pushrod from the mode valve lever and remove the vacuum actuator.
10. Release the mode valve lever.

INSTALLATION PROCEDURE

Picture 9

1. Fully extend the mode valve actuator pushrod.
2. Rotate the mode valve lever fully forward (counterclockwise) and hold in place until instructed.
3. Connect the mode vacuum actuator pushrod to the mode valve lever.

Picture 10

4. With the vacuum actuator below the HVAC module case mounting pins, slide the vacuum actuator forward in the vehicle, past the pins.
5. Carefully rotate the vacuum actuator toward the rear of the vehicle until the actuator slots engage onto the mounting pins on the HVAC module case.
6. Check that the vacuum actuator pushrod is not binding on the mode valve lever.
7. Push the vacuum actuator toward the HVAC module case to secure the retaining tab.
8. Release the mode valve lever.

Picture 11

9. Install a new tie strap (1) to the base of the mode vacuum actuator.
10. Connect the vacuum lines to the actuator.
11. Install the knee bolster.
12. Install the left instrument panel insulator.

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I wish I could be there to help. Let me know if you have questions or need anything.

Take care,

Joe