Engine Cooling System: Other Chevrolet Silverado 1500 HD

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS .

Tools Required

J 24731 Tempil Stick

Use one of the following procedures in testing for a malfunctioning thermostat.

1. J 24460-01 Cooling System Pressure Tester
2. J 42401 Radiator Cap/Surge Tank Test Adapter

J 24460-01 Cooling System Pressure Tester

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1. Remove the pressure cap.
2. Test the operation of the pressure cap. Refer to «Pressure Cap Testing»(ref-188992-S36154838822005091300000) .
3. Wash the pressure cap mating surface with water.
4. Use the J 24460-01 in order to apply pressure to the cooling system. Do not exceed the pressure cap rating.
5. The cooling system should hold the rated pressure for at least 2 minutes. Observe the gage for any pressure loss.
6. Repair any leaks as required.

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Radiator Cleaning

Note. The radiator fins are necessary for good heat transfer. Do not brush the fins. This may cause damage to the fins, reducing heat transfer.

1. Some conditions may require the use of warm water and a mild detergent.
2. Clean the A/C condenser fins.
3. Clean between the A/C condenser and radiator.
4. Clean the radiator cooling fins.
5. Straighten any damaged cooling fins.
6. Vehicles equipped with a diesel engine, clean between the charged air cooler and the A/C condenser also. Removal of the charge air cooler may be necessary to clean the fins.

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1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
2. Remove the air cleaner assembly. Refer to «AIR CLEANER ASSEMBLY»(ref-157348-S20542739702003081300000) .
3. Remove the surge tank overflow hose from the surge tank.
4. Disconnect the coolant level sensor electrical connector (3).
5. Reposition the surge tank inlet and outlet hose clamps.
6. If equipped with a 4.3 L, 4.8 L, 5.3 L, 6.0 L, or 8.1 L engine, remove the surge tank inlet (1) and outlet (2) hoses from the surge tank.
7. Reposition the surge tank inlet hose clamp from the surge tank.
8. Remove the surge tank inlet hose (1) from the surge tank.
9. Reposition the surge tank outlet hose clamp from the surge tank.
10. Remove the surge tank outlet hose (2) from the surge tank.
11. Remove the bolt from the surge tank.
12. Remove the nut from the surge tank.
13. Remove the surge tank.

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1. Install the surge tank. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) .
2. Install the bolt to the surge tank. Tighten Tighten the bolt to 9 N.m (80 lb in).
3. Install the nut to the surge tank. Tighten Tighten the nut to 9 N.m (80 lb in).
4. Install the surge tank outlet hose (2) to the surge tank.
5. Position the surge tank outlet hose clamp to the surge tank.
6. Install the surge tank inlet hose (1) to the surge tank.
7. Position the surge tank inlet hose clamp to the surge tank.
8. Connect the coolant level sensor electrical connector (3).
9. Install the surge tank overflow hose.
10. Install the air cleaner assembly. Refer to «AIR CLEANER ASSEMBLY»(ref-157348-S20542739702003081300000) .
11. Fill the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .

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1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
2. Reposition the surge tank inlet hose clamp from the radiator.
3. Remove the surge tank inlet hose from the radiator.
4. Reposition the surge tank inlet hose clamp from the surge tank.
5. Remove the surge tank inlet hose (1) from the surge tank.

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1. Install the surge tank inlet hose (1) to the surge tank.
2. Position the surge tank inlet hose clamp to the surge tank.
3. Install the surge tank inlet hose to the radiator.
4. Position the surge tank inlet hose clamp to the radiator.
5. Fill the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .

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1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
2. Separate the MAF/IAT sensor assembly and the air inlet tube by loosening the hose clamp.
3. Disconnect the PCV hose from the air cleaner outlet duct.
4. Remove the air inlet tube and resonator retaining wing nut.
5. Remove the air inlet tube and resonator from the throttle body by pivoting the air inlet tube and resonator upward until the hinge clip releases from the lip on the throttle body.
6. Remove the radiator inlet hose from the support.
7. Remove the radiator inlet hose from the radiator.
8. Remove the radiator inlet hose from the thermostat housing.
9. Remove the radiator inlet hose.

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1. Install the radiator inlet hose to the thermostat housing.
2. Install the radiator inlet hose to the radiator.
3. Install the radiator inlet hose to the support.
4. Align the hinge clip with the lip on the throttle body. Install the air inlet tube and resonator to the throttle body by pivoting the air inlet tube and resonator downward until the mounting stud is through the hole in the air inlet tube.
5. Install the resonator retaining wing nut.
6. Connect the PCV hose to the air cleaner outlet duct.
7. Connect the MAF/IAT sensor assembly harness connector.
8. Fill the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .

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1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
2. Loosen the air cleaner outlet duct clamps at the following locations: Throttle body Mass airflow/intake air temperature (MAF/IAT) sensor
3. Remove the radiator inlet hose clip from the outlet hose.
4. Remove the air cleaner outlet duct.
5. If necessary, remove the engine sight shield. Refer to «ENGINE SIGHT SHIELD REPLACEMENT (4.8L, 5.3L, and 6.0L Engines)»(ref-188991-S42495646762005091300000) or «ENGINE SIGHT SHIELD REPLACEMENT (6.0L ENGINE W/RPOS Y91 and Z88)»(ref-188991-S20954745852005091300000) .
6. Remove the radiator vent inlet hose from the radiator inlet hose clips.
7. Reposition the inlet hose clamp at the radiator.
8. Remove the inlet hose clip from the fan shroud.
9. Remove the inlet hose from the radiator.
10. Reposition the inlet hose clamp at the water pump.
11. Remove the inlet hose from the water pump.

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1. Install the inlet hose to the water pump.
2. Position the inlet hose clamp at the water pump.
3. Install the inlet hose to the radiator.
4. Position the inlet hose clamp at the radiator.
5. Install the inlet hose clip to the fan shroud.
6. Install the radiator vent inlet hose to the radiator inlet hose clips.
7. If necessary, install the engine sight shield. Refer to «ENGINE SIGHT SHIELD REPLACEMENT (4.8L, 5.3L, and 6.0L Engines)»(ref-188991-S42495646762005091300000) or «ENGINE SIGHT SHIELD REPLACEMENT (6.0L ENGINE W/RPOS Y91 and Z88)»(ref-188991-S20954745852005091300000) . IMPORTANT: Align the arrow at the throttle body end of the duct with the throttle body attaching stud.
8. Install the air cleaner outlet duct.
9. Install the radiator inlet hose clip to the outlet duct.
10. Tighten the air cleaner outlet duct clamps at the following locations: Throttle body MAF/IAT sensor Tighten Tighten the air cleaner outlet duct clamp screws to 7 N.m (62 lb in).
11. Fill the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .

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1. Drain the engine coolant. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
2. Move the hose clamps back on the radiator inlet hose.
3. Remove the radiator inlet hose from the radiator.
4. Remove the radiator inlet hose from the water outlet tube.

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1. Install the radiator inlet hose to the water outlet tube.
2. Install the radiator inlet hose to the radiator.
3. Install the hose clamps on the radiator outlet hose.
4. Fill the engine coolant. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .

J 46406 Fan Clutch Remover and Installer

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1. Remove the upper fan shroud. Refer to «Fan Shroud Replacement - Upper (W/O M74)»(ref-188992-S11141372892005091300000) or «Fan Shroud Replacement - Upper (W/M74)»(ref-188992-S15776187022005091300000) .
2. Install the J 46406 to the fan clutch.
3. Remove the fan hub nut from the water pump in a counterclockwise rotation.
4. Remove the fan clutch bolts from the rear of the fan blade.
5. Separate the fan clutch from the fan blade.

J 46406 Fan Clutch Remover and Installer

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1. Remove the upper fan shroud. Refer to «Fan Shroud Replacement - Upper (W/O M74)»(ref-188992-S11141372892005091300000) or «Fan Shroud Replacement - Upper (W/M74)»(ref-188992-S15776187022005091300000) .
2. Install the J 46406 to the fan clutch.
3. Remove the fan hub nut from the water pump in a counterclockwise rotation.
4. Remove the fan clutch bolts from the rear of the fan blade.
5. Separate the fan clutch from the fan blade.

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1. Install the fan clutch bolts from the rear of the fan blade. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) .
2. Install the fan clutch bolts. Tighten Tighten the bolts to 23 N.m (17 lb ft).
3. Install the fan assembly.
4. Install the J 46406 to the fan clutch. Tighten Tighten the nut clockwise to 56 N.m (41 lb ft).
5. Install the upper fan shroud. Refer to «Fan Shroud Replacement - Upper (W/O M74)»(ref-188992-S11141372892005091300000) or «Fan Shroud Replacement - Upper (W/M74)»(ref-188992-S15776187022005091300000) .

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1. Remove the fan clutch. Refer to «Fan Clutch Replacement»(ref-188992-S34461718282005091300000) .
2. Disconnect the camshaft position (CMP) sensor electrical connector (1).
3. Remove the fan pulley bolts/nuts.
4. Remove the fan pulley.
5. Remove the fan pulley spacer.

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1. Install the fan pulley spacer.
2. Install the fan pulley. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) .
3. Install the fan pulley bolts/nuts. Tighten Tighten the bolts/nuts to 46 N.m (34 lb ft).
4. Connect the CMP sensor electrical connector (1).
5. Install the fan clutch. Refer to «Fan Clutch Replacement»(ref-188992-S34461718282005091300000) .

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1. Loosen the outlet duct clamp at the upper intake manifold cover.
2. Remove the upper intake manifold cover from the outlet duct.
3. Remove the upper intake manifold cover.
4. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
5. Disconnect the turbocharger coolant return hose from the turbocharger bypass valve.
6. Remove the turbocharger bypass valve and washer.

J 43181 Heater Line Quick Connect Release Tool

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1. Loosen the outlet duct clamp at the upper intake manifold cover.
2. Remove the upper intake manifold cover from the outlet duct.
3. Remove the upper intake manifold cover.
4. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
5. Disconnect the negative battery cables. Refer to «BATTERY NEGATIVE CABLE DISCONNECT/CONNECT PROCEDURE (SINGLE BATTERY)»(ref-188993-S31717251372005091300000) or «BATTERY NEGATIVE CABLE DISCONNECT/CONNECT PROCEDURE (AUXILIARY BATTERY)»(ref-188993-S36299735782005091300000) . IMPORTANT: After removing the turbocharger air ducts, cover the openings with tape to prevent entry of objects.
6. Loosen the outlet duct clamps at the turbocharger and the mass air flow/intake air temperature (MAF/IAT) sensor.
7. Remove the outlet duct.
8. Loosen the charged air cooler outlet duct to intake hose clamp (1). IMPORTANT: Do not use a screwdriver or other tool to pry the hose loose. The hose can be torn or damage. Loosen the hose by twisting.
9. Remove the charged air cooler duct from the intake.
10. Remove the generator positive cable nut.
11. Remove the positive cable from the generator.
12. Disconnect the generator electrical connector (1).
13. Remove the ribbed idler pulley from the generator bracket.
14. Remove the generator bracket and position to the side. The generator does not require removal. The drive belt tensioner does not require removal.
15. Disconnect the fuel injection control module electrical connectors (2).
16. Remove the fuel line bolts.
17. Remove the fuel lines (2) from the fuel injection control module.
18. Using J 43181, disconnect the inlet heater hose from the heater core inlet.
19. Remove the fuel injection control module wiring harness conduit from the heater pipe.
20. Remove the heater inlet pipe to fuel filter bolt.
21. Remove the heater inlet pipe to thermostat housing bolt.
22. Remove the heater inlet pipe with O-ring seal from the thermostat housing.
23. Remove the turbocharger coolant feed pipe bracket bolts.
24. Remove the turbocharger coolant return hose clamps and hose.
25. Disconnect the turbocharger coolant feed hose from the turbocharger.
26. Remove the turbocharger coolant feed pipe nut.
27. Remove the coolant feed pipe.
28. Disconnect the turbocharger coolant return hose from the turbocharger coolant bypass valve.
29. Disconnect the turbocharger coolant return hose from the turbocharger.

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1. Connect the turbocharger coolant return hose and clamp to the turbocharger coolant bypass valve.
2. Connect the turbocharger coolant return hose and clamp to the turbocharger.
3. Install the turbocharger coolant feed pipe. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) .
4. Install the turbocharger coolant feed pipe nut. Tighten Tighten the nut to 9 N.m (80 lb in).
5. Connect the turbocharger coolant feed hose and clamps to the turbocharger and the coolant pipe.
6. Install the turbocharger coolant return hose and clamps.
7. Install the turbocharger coolant feed pipe bracket bolts. Tighten Tighten the bolts to 21 N.m (15 lb ft).
8. Install a NEW O-ring seal to the heater inlet pipe.
9. Install the heater inlet pipe to the thermostat housing.
10. Install the heater inlet pipe to thermostat housing bolt. Tighten Tighten the bolt to 21 N.m (15 lb ft).
11. Install the heater inlet pipe to fuel filter bolt. Tighten Tighten the bolt to 21 N.m (15 lb ft).
12. Connect the inlet heater hose to the heater inlet.
13. Install the fuel injection control module wiring harness conduit to the heater pipe.
14. Install the generator bracket and bolts. Tighten Tighten the bolts to 50 N.m (37 lb ft).
15. Install the ribbed idler pulley and bolt. Tighten Tighten the bolt to 43 N.m (32 lb ft).
16. Install the fuel lines (2) to the fuel injection control module.
17. Install the fuel line bolts. Tighten Tighten the bolts to 35 N.m (26 lb ft).
18. Connect the fuel injection control module electrical connectors (2).
19. Install the generator positive cable and nut. Tighten Tighten the nut to 9 N.m (80 lb in).
20. Connect the generator electrical connector (1).
21. Remove the tape from the turbocharger openings.
22. Install the charged air cooler outlet duct to the intake.
23. Align the mark on the duct (3) with the alignment mark on the intake.
24. Position the clamp (1) as shown for proper clearance. Tighten Tighten the clamps to 6 N.m (53 lb in).
25. Install the outlet duct to the turbocharger.
26. Align the outlet duct alignment indicator (1) to the turbocharger alignment indicator (2). IMPORTANT: The outlet duct must be fully seated against the MAT/IAT sensor with the edge of the seal in the vertical position.
27. Install the outlet duct to the MAT/IAT sensor.
28. Tighten the outlet duct clamps at the turbocharger and the MAT/IAT sensor. Tighten Tighten the clamps to 6 N.m (53 lb in).
29. Install the upper intake manifold cover.
30. Install the upper intake manifold cover to the outlet duct.
31. Tighten the outlet duct clamp at the upper intake manifold cover. Tighten Tighten the clamp to 6 N.m (53 lb in).
32. Fill the cooling. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
33. Connect the negative battery cable. Refer to «BATTERY NEGATIVE CABLE DISCONNECT/CONNECT PROCEDURE (SINGLE BATTERY)»(ref-188993-S31717251372005091300000) or «BATTERY NEGATIVE CABLE DISCONNECT/CONNECT PROCEDURE (AUXILIARY BATTERY)»(ref-188993-S36299735782005091300000) .

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1. Loosen the outlet duct clamp at the upper intake manifold cover.
2. Remove the upper intake manifold cover from the outlet duct.
3. Remove the upper intake manifold cover.
4. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
5. Remove the radiator inlet hose from the water outlet tube.
6. Remove the bolt and wiring harness bracket at the thermostat housing.
7. Disconnect the turbocharger coolant return hose from the turbocharger bypass valve.
8. Remove the turbocharger bypass valve and sealing washer from the water outlet tube.
9. Remove the water outlet bolts.
10. Remove the water outlet.
11. Remove and discard the O-ring seal.

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1. Install a NEW O-ring seal onto the water outlet.
2. Lightly lubricate the O-ring seal with coolant.
3. Install the water outlet. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) .
4. Install the water outlet tube bolts. Tighten Tighten the bolt to 21 N.m (15 lb ft).
5. Install the turbocharger bypass valve and washer. Tighten Tighten the valve to 60 N.m (44 lb ft).
6. Connect the turbocharger coolant return hose to the turbocharger bypass valve.
7. Install the bolt and wiring harness bracket to the thermostat housing. Tighten Tighten the bolt to 8 N.m (71 lb in).
8. Install the radiator inlet hose to the water outlet tube.
9. Fill the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
10. Install the upper intake manifold cover.
11. Install the upper intake manifold cover to the outlet duct.
12. Tighten the outlet clamp at the upper intake manifold cover. Tighten Tighten the clamp to 6 N.m (53 lb in).

J 41240 Fan Clutch Remover and Installer

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1. Loosen the air cleaner outlet duct clamp at the mass airflow/intake air temperature sensor.
2. Remove the positive crankcase ventilation (PCV) hose.
3. Remove the air cleaner adapter nut.
4. In order to remove the air cleaner outlet duct, pivot the duct upward until the hinge clip release from the lip on the throttle body.
5. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
6. Remove the cooling fan. Refer to «Fan Replacement»(ref-188992-S38409126652005091300000) .
7. Remove the drive belt. Refer to «DRIVE BELT ROUTING»(ref-166550-S34031604972004092300000) .
8. Reposition the radiator outlet hose clamps at the surge tank and water pump.
9. Remove the radiator outlet hose from the surge tank.
10. Remove the radiator outlet hose from the water pump.
11. Reposition the water pump inlet hose clamps.
12. Remove the water pump inlet hose.
13. Using J 41240, hold the water pump pulley, remove the water pump pulley bolts.
14. Remove the water pump bolts.
15. Remove the water pump.
16. Remove and discard the water pump gaskets.
17. Clean and inspect the water pump, if necessary. Refer to «INSPECTION»(ref-161511-S11831720022004041300000) .

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1. If reusing the old fasteners, apply sealant GM P/N 12346004, (Canadian P/N 10953480), or equivalent to the threads of the water pump bolts.
2. Install NEW water pump gaskets and the water pump. NOTE: Refer to «FASTENER NOTICE»(ref-175132-S17785009232005041500000) .
3. Install the water pump bolts. Tighten Tighten the bolts to 45 N.m (33 lb ft).
4. Using J 41240, hold the water pump pulley, install the water pump pulley bolts. Tighten Tighten the bolts to 25 N.m (18 lb ft). IMPORTANT: After assembly, the hose clamp tangs (water pump end) must point forward and the upper tang should be level with the outside diameter of the water pump inlet hose.
5. Install the water pump inlet hose.
6. Position the water pump inlet hose clamps.
7. Install the radiator outlet hose to the water pump.
8. Install the radiator outlet hose to the surge tank.
9. Position the radiator outlet hose clamps at the surge tank and water pump.
10. Install the drive belt. Refer to «DRIVE BELT ROUTING»(ref-166550-S34031604972004092300000) .
11. Install the cooling fan. Refer to «Fan Clutch Replacement»(ref-188992-S34461718282005091300000) .
12. Align the hinge clip with the lip on the throttle body. In order to install the air cleaner outlet duct, pivot the air cleaner outlet duct downward until the mounting stud is through the hole.
13. Install the air cleaner adapter nut.
14. Install the PCV hose.
15. Tighten the air cleaner outlet duct clamp at the MAF/IAT sensor.
16. Fill the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
17. Inspect the cooling system for leaks.

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1. Drain the cooling system. Refer to «Draining and Filling Cooling System»(ref-188992-S10584397332005091300000) .
2. Loosen the air cleaner outlet duct clamps at the following locations: Throttle body Mass airflow/intake air temperature (MAF/IAT) sensor
3. Remove the radiator inlet hose clip from the outlet duct.
4. Remove the air cleaner outlet duct.
5. If necessary, remove the engine sight shield. Refer to «ENGINE SIGHT SHIELD REPLACEMENT (4.8L, 5.3L, and 6.0L Engines)»(ref-188991-S42495646762005091300000) or «ENGINE SIGHT SHIELD REPLACEMENT (6.0L ENGINE W/RPOS Y91 and Z88)»(ref-188991-S20954745852005091300000) .
6. Remove the radiator vent inlet hose from the radiator hose clips.
7. Reposition the inlet hose clamp at the water pump.
8. Remove the inlet hose from the water pump.
9. Remove the fan blade. Refer to «Fan Replacement»(ref-188992-S38409126652005091300000) .
10. Remove the accessory drive belt. Refer to «DRIVE BELT REPLACEMENT - ACCESSORY»(ref-188991-S29850027902005091300000) .
11. Reposition the outlet hose clamp at the water pump.
12. Remove the outlet hose from the water pump.
13. Reposition the surge tank outlet hose clamp at the water pump.
14. Remove the surge tank outlet hose from the water pump.
15. Reposition the heater inlet hose clamp at the water pump.
16. Remove the heater inlet hose from the water pump.
17. Remove the water pump bolts.
18. Remove the water pump and gaskets.
19. Discard the water pump gaskets.

CHECK COOLANT TEMP

The IPC illuminates the CHECK COOLANT TEMP indicator in the message center when the IPC determines that the coolant temperature is greater than 121°C (249.8°F). The IPC receives a class 2 message from the PCM indicating the coolant temperature.

ENGINE OVERHEATED

The IPC illuminates the ENGINE OVERHEATED indicator in the message center when the IPC determines that the coolant temperature is greater than 128°C (262°F). The IPC receives a class 2 message from the PCM indicating the coolant temperature.

LOW COOLANT

The IPC illuminates the LOW COOLANT indicator in the message center when the IPC detects a low coolant level condition from the PCM. The IPC receives a class 2 message from the PCM indicating the coolant level.

REDUCED ENGINE POWER

The IPC illuminates the REDUCED ENGINE POWER indicator in the message center when the IPC detects a reduced engine power condition from the PCM. The IPC receives a class 2 message from the PCM requesting illumination when the engine temperature reaches 132°C (270°F).

Coolant Level Control

The engine cooling system contains an engine coolant level switch to alert the driver in the event of a coolant loss. The powertrain control module (PCM) sends out a coolant loss signal over the coolant level switch signal circuit. When the engine coolant level switch reads a low coolant level in the fill tank, the switch opens. The instrument cluster has an internal logic which displays information on the message center. The logic receives power from the fuse block on 3 individual power circuits; ignition 3 voltage, off/run/crank voltage, and ignition 1 voltage circuit through the body wiring harness junction block. The message center receives it's power from engine wiring harness junction block on the battery positive voltage circuit. Ground is provided by the ground circuits via the body wiring harness junction block and the engine wiring harness junction block. The message center receives the signal from the logic and displays the LOW COOLANT message. The message is a continuous display shown in amber

Coolant Heater

The optional engine coolant heater (RPO K05) operates using 110-volt AC external power and is designed to warm the coolant in the engine block area for improved starting in very cold weather 29°C (20°F). The coolant heater helps reduce fuel consumption when a cold engine is warming up. The unit is equipped with a detachable AC power cord. A weather shield on the cord is provided to protect the plug when not in use.

The cooling system's function is to maintain an efficient engine operating temperature during all engine speeds and operating conditions. The cooling system is designed to remove approximately one-third of the heat produced by the burning of the air-fuel mixture. When the engine is cold, the coolant does not flow to the radiator until the thermostat opens. This allows the engine to warm quickly.

Cooling Cycle

Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. Coolant will then be pumped through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water pump outlet and into the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders, where it absorbs heat.

Some coolant is also pumped from the water pump to the heater core, then back to the water pump. This provides the passenger compartment with heat and defrost.

The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.

Coolant is also directed to the throttle body. There it circulates through passages in the casting. During initial start up, the coolant assists in warming the throttle body. During normal operating temperatures, the coolant assists in regulating the throttle body temperature.

Cooling Cycle (6.6L Diesel Engine)

Coolant is drawn from the radiator outlet and into the water pump inlet by the water pump. The coolant flows to the heater core while the engine is running. This provides the passenger compartment with heat and defrost.

Coolant is then pumped through the water pump outlet and through the coolant pipe to the engine oil cooler. The coolant flows around the oil cooler element and to the rear engine cover. The rear engine cover distributes the coolant flow to both banks of the engine block. In the engine block, the coolant circulates through the water jackets surrounding the cylinders where it absorbs heat.

The coolant is then forced through the cylinder head gasket openings and into the cylinder heads. In the cylinder heads, the coolant flows through the water jackets surrounding the combustion chambers and valve seats, where it absorbs additional heat.

Coolant is also directed to the turbocharger. There it circulates through passages in the center housing. During engine warm-up cycle the bypass valve located in the turbocharger inlet hose at the outlet pipe prevents coolant flow. During normal operating temperatures, the coolant assists in keeping the turbocharger cool.

From the cylinder heads, the coolant flows to the thermostats. The coolant flows from the thermostat housing to the water pump through the bypass pipe until the engine reaches 85°C (185°F).

Operation of the cooling system requires proper functioning of all cooling system components. The cooling system consists of the following components

Coolant

The engine coolant is a solution made up of a 50-50 mixture of DEX-COOL and suitable drinking water. The coolant solution carries excess heat away from the engine to the radiator, where the heat is dissipated to the atmosphere.

Radiator

The radiator is a heat exchanger. It consists of a core and two tanks. The aluminum core is a tube and fin crossflow design that extends from the inlet tank to the outlet tank. Fins are placed around the outside of the tubes to improve heat transfer to the atmosphere.

The inlet and outlet tanks are a molded, high temperature, nylon reinforced plastic material. A high temperature rubber gasket seals the tank flange edge to the aluminum core. The tanks are clamped to the core with clinch tabs. The tabs are part of the aluminum header at each end of the core.

The radiator also has a drain cock located in the bottom of the left hand tank. The drain cock unit includes the drain cock and drain cock seal.

The radiator removes heat from the coolant passing through it. The fins on the core transfer heat from the coolant passing through the tubes. As air passes between the fins, it absorbs heat and cools the coolant.

Surge Tank

The surge tank is a plastic tank with a threaded pressure cap. The tank is mounted at a point higher than all other coolant passages. The surge tank provides an air space in the cooling system that allows the coolant to expand and contract. The surge tank provides a coolant fill point and a central air bleed location.

During vehicle use, the coolant heats and expands. The increased coolant volume flows into the surge tank. As the coolant circulates, any air is allowed to bubble out. Coolant without air bubbles absorbs heat much better than coolant with bubbles.

Pressure Cap

The pressure cap seals the cooling system. It contains a blow off or pressure relief valve and a vacuum or atmospheric valve. The pressure valve is held against its seat by a spring, which protects the radiator from excessive cooling system pressure. The vacuum valve is held against its seat by a spring, which permits opening of the valve to relieve vacuum created in the cooling system as it cools off. The vacuum, if not relieved, might cause the radiator and/or coolant hoses to collapse.

The pressure cap allows cooling system pressure to build up as the temperature increases. As the pressure builds, the boiling point of the coolant increases. Engine coolant can be safely run at a temperature much higher than the boiling point of the coolant at atmospheric pressure. The hotter the coolant is, the faster the heat transfers from the radiator to the cooler, passing air.

The pressure in the cooling system can get too high. When the cooling system pressure exceeds the rating of the pressure cap, it raises the pressure valve, venting the excess pressure.

As the engine cools down, the temperature of the coolant drops and a vacuum is created in the cooling system. This vacuum causes the vacuum valve to open, allowing outside air into the surge tank. This equalizes the pressure in the cooling system with atmospheric pressure, preventing the radiator and coolant hoses from collapsing.

Cooling Fan and Clutch

The engine cooling fan and clutch are driven by the crankshaft via the drive belt. The cooling fan draws air through the radiator to improve the transfer of heat from the coolant to the atmosphere. As the fan blades spin, they pull cool, outside air past the radiator core. The fan clutch drives the cooling fan. The fan clutch controls the amount of torque that is transmitted from the crankshaft to the fan blades. The clutch allows more torque to engage on the fan when the engine operating temperature increases and/or the vehicle speed is low. As the torque increases, the fan turns more quickly. The fan clutch decreases the torque applied to the cooling fan when the engine temperature decreases and/or the vehicle speed is high. As the torque decreases, the fan speed decreases.

Air Baffles and Seals

The cooling system uses deflectors, air baffles and air seals to increase cooling system capability. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle and through the radiator to increase engine cooling. Air baffles are also used to direct airflow through the radiator and increase cooling capability. Air seals prevent air from bypassing the radiator and A/C condenser, and prevent recirculation of hot air for better hot weather cooling and A/C condenser performance.

Water Pump

The water pump is a centrifugal vane impeller type pump. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is mounted on the pump shaft and consists of a series of flat or curved blades or vanes on a flat plate. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force.

The impeller shaft is supported by one or more sealed bearings. The sealed bearings never need to be lubricated. Grease cannot leak out, dirt and water cannot get in as long as the seal is not damaged or worn.

The purpose of the water pump is to circulate coolant throughout the cooling system. The water pump is driven by the crankshaft via the drive belt.

Water Pump (6.6L Diesel Engine)

The water pump is a centrifugal vane impeller type pump. The water pump is gear driven by the crankshaft gear. The pump consists of a housing with coolant inlet and outlet passages and an impeller. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades or vanes. When the impeller rotates, the coolant between the vanes is thrown outward by centrifugal force. The impeller shaft is supported by bearings. Splash of the engine oil lubricates the bearings. The bearings and shaft are sealed to prevent engine oil to mix with the coolant. If the seal fails, coolant will leak out the vent hole in the water pump housing.

The purpose of the water pump is to circulate coolant throughout the cooling system.

Thermostat

The thermostat is a coolant flow control component. It's purpose is to help regulate the operating temperature of the engine. It utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a small piston. When the element is heated, it expands and exerts pressure against the small piston. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.

When the coolant temperature is below the rated thermostat opening temperature, the thermostat valve remains closed. This prevents circulation of the coolant to the radiator and allows the engine to warm up. After the coolant temperature reaches the rated thermostat opening temperature, the thermostat valve will open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. The thermostat also provides a restriction in the cooling system, after it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.

Thermostats (6.6L Diesel Engine)

The thermostats are coolant flow control components. The purpose of the thermostats are to regulate the correct operating temperature of the engine. The thermostats utilizes a temperature sensitive wax-pellet element. The element connects to a valve through a piston. When the element is heated, it expands and exerts pressure against a rubber piston. This pressure forces the valve to open. As the element is cooled, it contracts. This contraction allows a spring to push the valve closed.

The 6.6L diesel engine requires two thermostats for correct coolant flow. The front thermostat is a dual purpose thermostat. The front thermostat controls the coolant flow to the bypass port and to the water outlet. The rear thermostat only controls the coolant flow to the water outlet.

When the coolant temperature is below the rated thermostat opening temperature, the front thermostat valve remains closed to the water outlet and is opened to the bypass port. The bottom portion of the thermostat is raised off of the bypass port while at the same time the top portion closes the coolant flow to the water outlet. The rear thermostat also is closed to the water outlet during engine warm-up. This prevents circulation of the coolant to the radiator and allows the engine to warm up quickly. After the coolant temperature reaches 82°C (180°F) the front thermostat primary valve opening temperature, the front thermostat primary valve will start to open. The coolant is then allowed to circulate through the thermostat to the radiator where the engine heat is dissipated to the atmosphere. As the engine coolant reaches 85°C (185°F) and more coolant demand is required the front thermostat secondary valve begins to close the bypass port and the rear thermostat begins to open coolant flow to the water outlet. The thermostats will continue to control the coolant flow by opening and closing. The front thermostat will be fully open when the coolant temperature reaches 95°C (203°F) the rear thermostat will be fully open when the coolant temperature reaches 100°C (212°F). The thermostat also provides a restriction in the cooling system, even after the it has opened. This restriction creates a pressure difference which prevents cavitation at the water pump and forces coolant to circulate through the engine block.

Engine Oil Cooler

The engine oil cooler is a heat exchanger. It is located inside the left side end tank of the radiator. The engine oil temperature is controlled by the temperature of the engine coolant that surrounds the oil cooler in the radiator.

The engine oil pump, pumps the oil through the engine oil cooler line to the oil cooler. The oil then flows through the cooler where the engine coolant absorbs heat from the oil. The oil is then pumped through the oil cooler return line, to the oil filter, to the engine block oil system.

Engine Oil Cooler (6.6L Diesel Engine)

The engine oil cooler is a heat exchanger. The engine oil cooler is mounted to the left lower corner of the engine. The oil filter is attached to the oil cooler housing. The engine coolant flows around the oil cooler element. The oil cooler element is a series of plates. The engine oil temperature is regulated by the temperature of the engine coolant that surrounds the oil cooler as the engine oil passes through the cooler.

The engine oil pump, pumps the oil through the engine oil feed line to the oil cooler. The oil then flows down through the cooler while the engine coolant absorbs heat from the oil. The oil is then pumped through the oil return line, to the oil filter, then to the main engine oil passage.

Transmission Oil Cooler

The transmission oil cooler is a heat exchanger. It is located inside the right side end tank of the radiator. The transmission fluid temperature is regulated by the temperature of the engine coolant in the radiator.

The transmission oil pump, pumps the fluid through the transmission oil cooler line to the transmission oil cooler. The fluid then flows through the cooler where the engine coolant absorbs heat from the fluid. The fluid is then pumped through the transmission oil cooler return line, to the transmission.

Turbocharger Bypass Valve (6.6L Diesel Engine)

The turbocharger bypass valve is a temperature control valve. The valve is located in the turbocharger coolant inlet hose at the water outlet tube.

The purpose of the valve is to close the coolant flow through the turbocharger. Closing off the coolant flow through the turbocharger avoids turbocharger overcooling.

Scheme 355

Scheme 356