Thermostat-5.2L/5.9L engine

REMOVAL

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 is being replaced, be sure that replacement is specified thermostat for vehicle model and engine type.

Factory installed thermostat housings on 5.2L/5.9L engines are installed on a gasket with an anti-stick coating. This will aid in gasket removal and clean-up.

(1) Disconnect negative battery cable at battery.

(2) Drain cooling system until coolant level is below thermostat. Refer to Draining Cooling System in this group.

(3) Air Conditioned vehicles: Remove support bracket (generator mounting bracket-to-intake manifold) located near rear of generator (Fig. 44).

Fig. 44 Generator Support Bracket-5.2L/5.9L Engine

1 - IDLER PULLEY BUSHING

2 - A/C AND/OR GENERATOR MOUNTING BRACKET

3 - IDLER PULLEY

4 - SCREW AND WASHER

(4) On air conditioning equipped vehicles, the generator must be partially removed.

(a) Remove generator drive belt as follows: Drive belts on 5.2L/5.9L engines are equipped with a spring loaded automatic belt tensioner (Fig. 45).

(b) Attach a socket/wrench to pulley mounting bolt of automatic tensioner (Fig. 45).

(c) Rotate tensioner assembly clockwise (as viewed from front) until tension has been relieved from belt.

(d) Remove belt from vehicle.

(e) Remove two generator mounting bolts. Do not remove any wiring at generator. If equipped with 4WD, unplug 4WD indicator lamp wiring harness (located near rear of generator).

(f) Remove generator. Position generator to gain access for thermostat gasket removal.

Fig. 45 Automatic Belt Tensioner-5.2L/5.9L Engines

1 - IDLER PULLEY

2 - TENSIONER

3 - FAN BLADE

WARNING: CONSTANT TENSION HOSE CLAMPS ARE USED ON MOST COOLING SYSTEM HOSES.

ALWAYS WEAR SAFETY GLASSES WHEN SERVICING CONSTANT TENSION CLAMPS.

CAUTION: A number or letter is stamped into the tongue of constant tension clamps (Fig. 39). If replacement is necessary, use only an original equipment clamp with matching number or letter.

(5) Remove upper radiator hose clamp and upper radiator hose at thermostat housing.

(6) Position wiring harness (behind thermostat housing) to gain access to thermostat housing.

(7) Remove thermostat housing mounting bolts, thermostat housing, gasket and thermostat (Fig. 46).

Discard old gasket.

Fig. 46 Thermostat-5.2L/5.9L Engines

1 - THERMOSTAT HOUSING

2 - GASKET

3 - INTAKE MANIFOLD

4 - THERMOSTAT

5 - MACHINED GROOVE

INSTALLATION

(1) Clean mating areas of intake manifold and thermostat housing.

(2) Install thermostat (spring side down) into recessed machined groove on intake manifold (Fig.

46).

(3) Install gasket on intake manifold and over thermostat (Fig. 46).

(4) Position thermostat housing to intake manifold.

Note the word FRONT stamped on housing (Fig. 47).

For adequate clearance, this must be placed towards front of vehicle. The housing is slightly angled forward after installation to intake manifold.

(5) Install two housing-to-intake manifold bolts.

Tighten bolts to 23 N*m (200 in. lbs.) torque.

(6) Install upper radiator hose to thermostat housing.

(7) Air Conditioned vehicles:

CAUTION: When installing the serpentine accessory drive belt, the belt must be routed correctly. If not, engine may overheat due to water pump rotating in wrong direction. Refer to (Fig. 48) for correct engine belt routing. The correct belt with correct length must be used.

(a) Install generator. Tighten bolts to 41 N*m (30 ft. lbs.).

(b) Install support bracket (generator mounting bracket-to-intake manifold) (Fig. 44). Tighten bolts to 54 N*m (40 ft. lbs.) torque.

(c) Position drive belt over all pulleys except idler pulley (located between generator and A/C compressor).

(d) Attach a socket/wrench to pulley mounting bolt of automatic tensioner (Fig. 45).

(e) Rotate socket/wrench clockwise. Place belt over idler pulley. Let tensioner rotate back into place. Remove wrench. Be sure belt is properly seated on all pulleys.

(8) Fill cooling system. Refer to Refilling Cooling System in this group.

(9) Connect battery negative cable.

(10) Start and warm the engine. Check for leaks.

Fig. 47 Thermostat Position-5.2L/5.9L Engines

(b) Install support bracket (generator mounting bracket-to-intake manifold) (Fig. 44). Tighten bolts to 54 N*m (40 ft. lbs.) torque.

(c) Position drive belt over all pulleys except idler pulley (located between generator and A/C compressor).

(d) Attach a socket/wrench to pulley mounting bolt of automatic tensioner (Fig. 45).

(e) Rotate socket/wrench clockwise. Place belt over idler pulley. Let tensioner rotate back into place. Remove wrench. Be sure belt is properly seated on all pulleys.

(8) Fill cooling system. Refer to Refilling Cooling System in this group.

(9) Connect battery negative cable.

(10) Start and warm the engine. Check for leaks.