Testing Thermostat Opening Temperature

To Remove Thermostats

1. CAUTION: Explosive release of fluids from pressurized cooling system can cause serious burns. DO NOT drain coolant until it has cooled below operating temperature. Always loosen radiator pressure cap or drain valve slowly to relieve pressure.

   
   TS281-UN-15APR13

   High Pressure Fluids

   Visually inspect area around thermostat housing for leaks.

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2. Remove radiator pressure cap and partially drain cooling system.

3. 
   RG18563-UN-25MAY10

   Thermostats

   A - Thermostats

   Remove thermostat cover. Clean and check cover for cracks or damage.

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4. Remove both thermostats (A) from the housing.

Testing Thermostats Opening Temperature

RG5971-UN-23NOV97

Testing Thermostat Opening Temperature

1. NOTE: Perform the following test for both thermostats.

   Remove thermostats.

2. Visually inspect thermostats for corrosion or damage. Replace as a matched set as necessary.

   CAUTION: DO NOT allow thermostat or thermometer to rest against the side or bottom of container when heating water. Either may rupture if overheated.

3. Suspend thermostat and a thermometer in a container of water.

4. Stir the water as it heats. Observe opening action of thermostat and compare temperatures with the specification given in chart below.

   NOTE: Due to varying tolerances of different suppliers, initial opening and full open temperatures may vary slightly from specified temperatures.

   Item	Measurement	Specification
   Thermostat Opening-Nominal	Temperature	85°C (185°F)
   Thermostat Normal Operating Conditions	Temperature	83.5—95°C (183—203°F)

5. Remove thermostat and observe its closing action as it cools. In ambient air the thermostat should close completely. Closing action should be smooth and slow.

6. If any thermostat is defective, replace both thermostats.

To Install Thermostats

RG18563-UN-25MAY10

Installing Thermostats

A - Thermostats

B - Rubber Seal

1. Install new rubber seal (A) for each thermostat.

2. Install thermostats into housing.

3. Install thermostat cover and tighten thermostat cover cap screws to specifications.

   Item	Measurement	Specification
   Thermostat Cover Cap Screw	Torque	35 N·m (26 lb-ft)

4. Fill cooling system and check for leaks.

   IMPORTANT: Air must be expelled from cooling system when system is refilled. Loosen plug on top of thermostat housing to allow air to escape when filling system. Retighten plug after filling cooling system.