Thermostat: Service and Repair

REMOVAL

WARNING: DO NOT LOOSEN THE RADIATOR DRAINCOCK OR CAP WITH THE SYSTEM HOT AND PRESSURIZED. SERIOUS BURNS FROM THE COOLANT CAN OCCUR.

Do not waste reusable coolant. If the solution is clean, drain the coolant into a clean container for reuse.
If the thermostat is being replaced, be sure that the replacement is the specified thermostat for the vehicle model and engine type.
Factory installed thermostat housings on all 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.
(3) If equipped with air conditioning:
(a) Remove engine cover from vehicle interior.






(b) Remove the support bracket (generator mounting bracket-to-intake manifold) located near the rear of generator.






(c) The generator must be partially removed.
Drive belts on all engines are equipped with a spring loaded automatic belt tensioner. Remove the generator drive belt as follows:
(d) Attach a socket/wrench to the pulley mounting bolt of the automatic tensioner.
(e) Rotate the tensioner assembly clockwise (as viewed from front) until tension has been relieved from belt.
(f) Remove belt from generator pulley.
(g) Remove the two generator mounting bolts. Do not remove any wiring at generator.
(h) Remove generator. Position generator to gain access for thermostat gasket removal.






(i) Remove the three powertrain control module (PCM) mounting bolts and remove PCM. Do not disconnect 60-way connector from PCM. Lay PCM aside.







WARNING: CONSTANT TENSION HOSE CLAMPS ARE USED ON MOST COOLING SYSTEM HOSES. WHEN REMOVING OR INSTALLING, USE ONLY TOOLS DESIGNED FOR SERVICING THIS TYPE OF CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER 6094). SNAP-ON CLAMP TOOL (NUMBER HPC-20) MAY BE USED FOR LARGER CLAMPS. ALWAYS WEAR SAFETY GLASSES WHEN SERVICING CONSTANT TENSION CLAMPS.






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

(4) Remove upper radiator hose clamp. Remove upper radiator hose at thermostat housing.
(5) Position the wiring harness (behind the thermostat housing) to gain access to thermostat housing.






(6) Remove thermostat housing mounting bolts, thermostat housing, gasket and thermostat. Discard old gasket.

INSTALLATION
(1) Clean mating areas of intake manifold and thermostat housing.
(2) Install thermostat (spring side down) into recessed machined groove on intake manifold.
(3) Install gasket on intake manifold and over thermostat.






(4) Position the thermostat housing to the intake manifold. Note the word FRONT stamped on the housing. For adequate clearance, this must be placed towards the front of vehicle. The housing should be slightly angled forward after installation to intake manifold.
(5) Install two housing-to-intake manifold bolts. Tighten bolts to 24 Nm (18 ft. lbs.) torque.

CAUTION: Housing must be tightened evenly and thermostat must be centered into recessed groove in intake manifold. If not, it may result in a cracked housing, damaged intake manifold threads or coolant leak.

(6) Install upper radiator hose to thermostat housing.
(7) Air conditioned vehicles:
(a) Install generator. Tighten bolts to 41 Nm (30 ft. lbs.).
(b) Install support bracket (generator mounting bracket-to-intake manifold). Tighten bolts to 54 Nm (40 ft. lbs.) torque.






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

(c) Position the drive belt over all pulleys except the idler pulley (located between the generator and A/C compressor).
(d) Attach a socket/wrench to the pulley mounting bolt of the automatic tensioner.
(e) Rotate the socket/wrench clockwise. Place the belt over the idler pulley. Let tensioner rotate back into place. Remove wrench. Be sure belt is properly seated on all pulleys.
(f) Install PCM.
The following belt routing schematics are published from the latest information available at the time of publication. If anything differs between these schematics and the Belt Routing Label, use the schematics on Belt Routing Label. This label is located in the engine compartment.
(8) Fill cooling system.
(9) Connect battery negative cable.
(10) Start and warm engine. Check for leaks.
(11) Install engine cover (if A/C equipped).