Hummer H1 (2006+). Manual - part 182

4-8

Cooling System

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ENGINE COOLING SYSTEM SERVICE

Depressurizing/Draining

WARNING:  To avoid injury, do not remove the surge tank filler cap before depressurizing the cooling system when
the engine temperature is above 190°F (88°C).

1.

If the engine is hot, place a thick cloth over the surge tank filler cap. Turn the filler cap counterclockwise to first stop to release
the internal pressure (Figure  4-7).

2.

After the pressure has been vented, remove the cap (Figure  4-7).

3.

Open the drain valve and drain the system (Figure  4-6).

4.

Close the drain valve.

Replenishing/Bleeding

1.

Ensure the drain valve is closed and the heater control is set on heat (Figure  4-6).

2.

Fill the system (approximately two inches above the cold fill line on the surge tank) with Dex Cool antifreeze solution.

3.

Install a coolant system pressure tester and pump to approximately 10 psi.

4.

Locate the bleeder on the water crossover, EGR cooler hose, and on the upper right hand corner of the radiator. Open all the
bleeders and allow the coolant to flow steady before closing.

5.

Depressurize the system. Remove the pressure tester, adjust the coolant level as needed and install the filler cap (Figure  4-7).

6.

Start the engine and bring up to operating temperature.

WARNING:  To avoid injury, do not remove the surge tank filler cap before depressurizing the cooling system when
the engine temperature is above 190°F (88°C).

7.

Check the coolant level, the freeze protection level and for leaks. Adjust as necessary.

Figure 4-6:   Drain Valve

DRAIN VALVE

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 Cooling System  4-9

5745804

Figure 4-7:   Surge Tank and Filler Cap Location

RADIATOR REAR SUPPORT BRACKET REPLACEMENT

Removal

1.

Remove the left splash shield (Section 10).

2.

Remove the battery tray, the batteries, and the right splash shield (Section 12).

3.

Remove the radiator rear support bracket and the insulator from the radiator (Figure  4-8).

4.

Remove the support bracket from the airlift bracket (Figure  4-9).

Figure 4-8:   Insulator and Rear Support Bracket Location

SURGE TANK

FILLER CAP

SURGE

TANK

Expected Ambient
Temperature

Antifreeze/
Water Mixture

120° to -32° F
(49° to -36° C)

50% antifreeze/
50% water

Table 4-1: Antifreeze Preparation Guide

RADIATOR

INSULATOR

REAR SUPPORT BRACKET

4-10

Cooling System

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Installation

1.

Fasten the radiator rear support bracket to the airlift bracket with the bolts, washers, and locknuts. Do not tighten the locknuts
(Figure  4-9).

2.

Secure the insulator and the support bracket to the radiator with the washers and the locknut (Figure  4-8).

3.

Tighten all the locknuts to 26 lb-ft (35 N•m).

4.

Install the left splash shield (Section 10).

5.

Install the battery tray, the batteries, and the right splash shield (Section 12).

Figure 4-9:    Rear Support Bracket Mounting

SURGE TANK REPLACEMENT

Removal

1.

Drain the cooling system.

2.

Disconnect the radiator vent hose from the surge tank (Figure  4-10).

3.

Disconnect the surge tank-to-lower radiator hose from the surge tank.

4.

Disconnect the overflow hose from the surge tank.

5.

Disconnect the low coolant sensor wiring harness. 

6.

Loosen the clamps and remove the surge tank from the bracket.

Installation

1.

Secure the surge tank to the bracket with clamps (Figure  4-10).

2.

Connect the low coolant sensor wiring harness. 

3.

Connect the surge tank-to-lower radiator hose.

4.

Connect the radiator vent hose to the surge tank.

5.

Connect the overflow hose to the surge tank.

6.

Fill and purge the cooling system.

REAR

AIRLIFT BRACKET

SUPPORT BRACKET

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 Cooling System  4-11

5745804

Figure 4-10:   Surge Tank Replacement

SURGE TANK

BRACKET

OVERFLOW

HOSE

SURGE TANK-TO-LOWER

RADIATOR HOSE

LOW COOLANT

SENSOR

RADIATOR BLEEDER

VALVE

SURGE TANK-TO-UPPER

RADIATOR HOSE

11-1-05