DESCRIPTION
The cooling system consists of
- Radiator
- Electric Cooling fan
- Hydraulic Cooling Fan (Diesel Engine)
- Fan shroud
- Radiator pressure cap
- Thermostat
- Coolant reserve/overflow system
- EGR Cooler (Diesel Engine)
- Transmission oil cooler (if equipped with an automatic transmission)
- Coolant
- Water pump
- Hoses and hose clamps
Scheme 1
The cooling system regulates engine operating temperature. It allows the engine to reach normal operating temperature as quickly as possible, maintains normal operating temperature and prevents overheating.
The cooling system also provides a means of heating the passenger compartment. The cooling system is pressurized and uses a centrifugal water pump to circulate coolant throughout the system. A separate and remotely mounted, pressurized coolant tank using a pressure/vent cap is used.
OPERATION
The automatic belt tensioner maintains belt tension by using internal spring pressure, a pivoting arm and pulley to apply force against the drive belt.
Scheme 2
| 1 - TENSIONER |
|---|
| 2 - BOLT |
On all engines, the tensioner (1) is equipped with an indexing tang on back of tensioner and an indexing stop on tensioner housing. If a new belt is being installed, tang must be within approximately 6 - 8mm (0.24 - 0.32 in.) of indexing stop (i.e. tang is approximately between the two indexing stops). Belt is considered new if it has been used 15 minutes or less.
If the above specification cannot be met, check for
- The wrong belt being installed (incorrect length/width)
- Worn bearings on an engine accessory (A/C compressor, power steering pump, water pump, idler pulley or generator)
- Belt is not installed in pulley grooves
- A pulley on an engine accessory being loose
- Misalignment of an engine accessory
- Belt incorrectly routed.
Note. A used belt should be replaced if tensioner indexing arrow has moved to the minimum tension indicator. Tensioner travel stops at this point.
- Remove accessory drive belt «(Refer to COOLING/ACCESSORY DRIVE/DRIVE BELTS - REMOVAL)»(ref-255951-S25277980112007060500000) . WARNING: Because of high spring pressure, do not attempt to disassemble automatic tensioner. Unit is serviced as an assembly except for pulley on tensioner.
- Remove tensioner assembly bolt (2).
- Remove tensioner assembly (1) from mounting bracket.
Scheme 3
| 1 - TENSIONER |
|---|
| 2 - BOLT |
On all engines, the tensioner (1) is equipped with an indexing tang on back of tensioner and an indexing stop on tensioner housing. If a new belt is being installed, tang must be within approximately 6 - 8mm (0.24 - 0.32 in.) of indexing stop (i.e. tang is approximately between the two indexing stops). Belt is considered new if it has been used 15 minutes or less.
If the above specification cannot be met, check for
- The wrong belt being installed (incorrect length/width)
- Worn bearings on an engine accessory (A/C compressor, power steering pump, water pump, idler pulley or generator)
- Belt is not installed in pulley grooves
- A pulley on an engine accessory being loose
- Misalignment of an engine accessory
- Belt incorrectly routed.
Note. A used belt should be replaced if tensioner indexing arrow has moved to the minimum tension indicator. Tensioner travel stops at this point.
- Remove accessory drive belt «(Refer to COOLING/ACCESSORY DRIVE/DRIVE BELTS - REMOVAL)»(ref-255951-S25277980112007060500000) . WARNING: Because of high spring pressure, do not attempt to disassemble automatic tensioner. Unit is serviced as an assembly except for pulley on tensioner.
- Remove tensioner assembly bolt (1).
- Remove tensioner assembly (2) from mounting bracket.
Scheme 4
| 1 - TENSIONER |
|---|
| 2 - BOLT |
On all engines, the tensioner (1) is equipped with an indexing tang on back of tensioner and an indexing stop on tensioner housing. If a new belt is being installed, tang must be within approximately 6 - 8mm (0.24 - 0.32 in.) of indexing stop (i.e. tang is approximately between the two indexing stops). Belt is considered new if it has been used 15 minutes or less.
If the above specification cannot be met, check for
- The wrong belt being installed (incorrect length/width)
- Worn bearings on an engine accessory (A/C compressor, power steering pump, water pump, idler pulley or generator)
- Belt is not installed in pulley grooves
- A pulley on an engine accessory being loose
- Misalignment of an engine accessory
- Belt incorrectly routed.
Note. A used belt should be replaced if tensioner indexing arrow has moved to the minimum tension indicator. Tensioner travel stops at this point.
- Remove accessory drive belt «(Refer to COOLING/ACCESSORY DRIVE/DRIVE BELTS - REMOVAL)»(ref-255951-S25277980112007060500000) . WARNING: Because of high spring pressure, do not attempt to disassemble automatic tensioner. Unit is serviced as an assembly except for pulley on tensioner.
- Remove tensioner assembly bolt (2).
- Remove tensioner assembly (1) from mounting bracket.
Scheme 5
- Disconnect negative battery cable.
- Remove accessory drive belt. (Scheme 5)«(Refer to COOLING/ACCESSORY DRIVE/DRIVE BELTS - REMOVAL)»(ref-255951-S25277980112007060500000).
- Remove belt tensioner retaining bolt and remove tensioner (5) from bracket. (Scheme 5)
Coolant flows through the engine block absorbing the heat from the engine, then flows to the radiator where the cooling fins in the radiator transfers the heat from the coolant to the atmosphere. During cold weather the ethylene-glycol or propylene-glycol coolant prevents water present in the cooling system from freezing within temperatures indicated by mixture ratio of coolant to water.
When power is applied (110 volt AC) to the block heater, the heating element transfers heat through the aluminum engine block and into the coolant without directly penetrating the cooling system.
The engine cooling thermostats are a wax pellet driven, reverse poppet choke type. The thermostats have an air bleed located in the thermostat flange. The air bleed allows internal trapped air during cooling system filling to be released. The thermostat on the 2.7L and 3.5L engines are located on the lower left side of engine, near the front. The thermostat on both engines are on the inlet side of the water pump.
The thermostat on the 5.7L/6.1L gas powered engine is located beneath the thermostat housing (1) at the front of the intake manifold.
Scheme 6
| 1 - VENT VALVE |
|---|
| 2 - BYPASS VALVE |
| 3 - THERMOSTAT HOUSING SEAL |
| 4 - MAIN VALVE |
The thermostat on the 3.0L Diesel engine is integrated into the thermostat housing located at the front of the right intake manifold and is serviced as an assembly. A rubber seal is used to seal the thermostat housing to the intake manifold. The thermostat contains the following components
- Main Valve (4) - Controls coolant flow through the radiator
- Bypass Valve (2) - Controls coolant flow through the bypass passage to the inlet side of the water pump
- Vent Valve (1) - Vents the cooling system via a ball valve when it is filled and when the engine is running
- Thermostat Housing Seal (3)
A vent valve in the center of the cap will remain shut as long as the cooling system is pressurized. As the coolant cools, it contracts and creates a vacuum in cooling system. This causes the vacuum valve to open and coolant in reserve/overflow tank to be drawn through connecting hose into radiator. If the vacuum valve is stuck shut, or overflow hose is kinked, radiator hoses will collapse on cool-down.