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Thermostat

Engine, Cooling and Exhaust › Cooling System
Unified entry — merged from multiple cross-listed pages in the original manual.

Parts

PartThermostat
ManufacturerCHY
OEM part #68174083AA
Price$19.45

Labor

Replace0.9 hr
Warranty 0.0 hrSkill B
Procedures
Engine Coolant Thermostat - Removal6 steps
⚠ WARNING
Do not loosen radiator draincock with system hot and pressurized. Serious burns from coolant can occur.
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  1. Disconnect negative battery cable at battery.
  2. Drain cooling system Service and Repair.
  3. Raise vehicle on hoist.
  4. Remove splash shield.
  5. Remove lower radiator hose clamp and lower radiator hose at thermostat housing.
  6. Remove thermostat housing mounting bolts, thermostat housing and thermostat.
Engine Coolant Thermostat - Installation10 steps
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  1. Clean mating areas of timing chain cover and thermostat housing.
  2. Install thermostat (spring side down) into recessed machined groove on housing assembly. Make sure rubber seal locating tab is positioned in the corresponding notch in the housing.
  3. Position thermostat housing on timing chain cover.
  4. Install two housing-to-timing chain cover bolts. Tighten bolts to 12 Nm (105 in. lbs.) torque.
  5. Install lower radiator hose on thermostat housing.
  6. Install splash shield.
  7. Lower vehicle.
  8. Fill cooling system Service and Repair.
  9. Connect negative battery cable to battery.
  10. Start and warm the engine. Check for leaks.
Engine Coolant Thermostat - Descriptionreference
△ CAUTION
Do not operate an engine without a thermostat, except for servicing or testing.
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GAS ENGINES A pellet-type thermostat (5) controls the operating temperature of the engine by controlling the amount of coolant flow to the radiator. On all engines the thermostat is closed below 195°F (90°C). Above this temperature, coolant is allowed to flow to the radiator. This provides quick engine warm up and overall temperature control. On the 3.7L engine the thermostat is designed to block the flow of the coolant bypass journal by 50% instead of completely blocking the flow. This design controls coolant temperature more accurately. The same thermostat is used for winter and summer seasons. An engine should not be operated without a thermostat, except for servicing or testing. Operating without a thermostat causes other problems. These are: longer engine warmup time, unreliable warmup performance, increased exhaust emissions and crankcase condensation. This condensation can result in sludge formation.
Factory service manual
From the 2008 KK factory manual — descriptions, specs, torque & procedures for this part.
DESCRIPTION-THERMOSTAT-2.8L DIESEL📷 1
1 - GASKET 2 - THERMOSTAT HOUSING 3 - BOLT(S) 4 - BRACKET
A pellet-type thermostat controls the operating temperature of the engine by controlling the amount of coolant flow to the radiator.
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DESCRIPTION-THERMOSTAT-3.7L📷 2
1 - FROM HEATER 2 - FROM RADIATOR 3 - TO WATER PUMP 4 - ENGINE BYPASS 5 - THERMOSTAT
CAUTION: Do not operate an engine without a thermostat, except for servicing or testing.
A pellet-type thermostat (5) controls the operating temperature of the engine by controlling the amount of coolant flow to the radiator. On all engines the thermostat is closed below 195°F (90°C). Above this temperature, coolant is allowed to flow to the radiator. This provides quick engine warm up and overall temperature control. On the 3.7L engine the thermostat is designed to block the flow of the coolant bypass journal by 50% instead of completely blocking the flow. This design controls coolant temperature more accurately.
The same thermostat is used for winter and summer seasons. An engine should not be operated without a thermostat, except for servicing or testing. Operating without a thermostat causes other problems. These are: longer engine warmup time, unreliable warmup performance, increased exhaust emissions and crankcase condensation. This condensation can result in sludge formation.

Operation

The thermostat starts to open at 80°C (176°F). Above this temperature, coolant is allowed to flow to the radiator. This provides quicker engine warmup and overall temperature control.
The same thermostat is used for winter and summer seasons. An engine should not be operated without a thermostat, except for servicing or testing. Operating without a thermostat causes other problems. These are: longer engine warmup time, unreliable warmup performance, increased exhaust emissions and crankcase condensation. This condensation can result in sludge formation.
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ON-BOARD DIAGNOSTICS
All models are equipped with On-Board Diagnostics for certain cooling system components. If the Powertrain Control Module (PCM) detects low engine coolant temperature, it will record a Diagnostic Trouble Code (DTC). For other DTC numbers, refer to OPERATION .
REMOVAL- 3.7L
1 - THERMOSTAT HOUSING 2 - THERMOSTAT LOCATION 3 - THERMOSTAT AND GASKET 4 - TIMING CHAIN COVER
WARNING: Do not loosen radiator draincock with system hot and pressurized. Serious burns from coolant can occur.
Do not waste reusable coolant. If solution is clean, drain coolant into a clean container for reuse.
If thermostat (3) is being replaced, be sure that replacement is specified thermostat for vehicle model and engine type.
  1.   Disconnect negative battery cable at battery.
  2.   Drain cooling system. See STANDARD PROCEDURE.
  3.   Raise vehicle on hoist.
  4.   Remove splash shield.
  5.   Remove lower radiator hose clamp and lower radiator hose at thermostat housing.
  6.   Remove thermostat housing mounting bolts, thermostat housing and thermostat.
REMOVAL-2.8L DIESEL📷 1
1.   Disconnect negative battery cable.
  2.   Remove engine cover. Refer to REMOVAL .
  3.   Partially drain cooling system. See STANDARD PROCEDURE.
  4.   Disconnect upper radiator hose and bypass hoses at thermostat housing (2).
  5.   Remove thermostat housing retaining bolts, support bracket and housing from cylinder head, discard
gasket.
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REMOVAL-4.0L📷 2
1 - UPPER RADIATOR HOSE 2 - HOSE CLAMP 3 - THERMOSTAT HOUSING MOUNTING BOLT 4 - THERMOSTAT HOUSING 5 - UPPER RADIATOR HOSE TUBE 6 - UPPER RADIATOR HOSE TUBE MOUNTING NUTS
  1.   Disconnect and isolate negative battery cable
  2.   Drain cooling system. See STANDARD PROCEDURE.
  3.   Remove air housing (Refer to REMOVAL ).
  4.   Remove upper intake manifold. Refer to REMOVAL .
  5.   Remove radiator tube mounting nuts.
  6.   Remove radiator hose at thermostat housing.
  7.   Remove thermostat housing bolts, thermostat housing and thermostat.
  8.   Clean thermostat housing mating surface on lower intake manifold.
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INSTALLATION- 3.7L📷 1
1 - THERMOSTAT HOUSING 2 - THERMOSTAT LOCATION 3 - THERMOSTAT AND GASKET 4 - TIMING CHAIN COVER
1. Clean mating areas of timing chain cover and thermostat housing. 2. Install thermostat (spring side down) into recessed machined groove on housing assembly. Make sure rubber seal locating tab is positioned in the corresponding notch in the housing. 3. Position thermostat housing on timing chain cover. 4. Install two housing-to-timing chain cover bolts. Tighten bolts to 12 N.m (105 in. lbs.) torque. 5. Install lower radiator hose on thermostat housing. 6. Install splash shield. 7. Lower vehicle. 8. Fill cooling system. See STANDARD PROCEDURE. 9. Connect negative battery cable to battery. 10. Start and warm the engine. Check for leaks.

Installation

1
Clean old gasket material from cylinder head and thermostat housing.
2
Install thermostat housing with gasket and support bracket to cylinder head. Torque bolts to 28 N.m. (250
in. lbs.).
3
Connect coolant bypass hose and upper radiator hose to thermostat housing.
4
Refill cooling system. See STANDARD PROCEDURE.
5
Install engine cover. Refer to INSTALLATION .
6
Connect negative battery cable.
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INSTALLATION-4.0L📷 1
1 - UPPER RADIATOR HOSE 2 - HOSE CLAMP 3 - THERMOSTAT HOUSING MOUNTING BOLT 4 - THERMOSTAT HOUSING 5 - UPPER RADIATOR HOSE TUBE 6 - UPPER RADIATOR HOSE TUBE MOUNTING NUTS
1. Make sure jiggle pin is at the 12 O'clock position. Position thermostat and thermostat housing lower intake manifold. 2. Install thermostat housing bolts. Tighten bolts to 35 N.m (25 ft. lbs.). 3. Install upper radiator hose onto thermostat housing 4. Position upper radiator hose tube and install mounting nuts. Tighten nuts to 9 N.m, (85 in. lbs.). 5. Install upper intake manifold. Refer to INSTALLATION . 6. Install air cleaner housing (Refer to INSTALLATION ). 7. Fill cooling system. See STANDARD PROCEDURE.
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