Test coolant thermostat - AR20.10-P-2455GZ

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ENGINE 113.964 in MODEL 164.175

Fig 1: Identifying Coolant Thermostat And Valve

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

	Remove/install
	Risk of injury to skin and eyes caused by scalding from contact with hot coolant spray. Risk of poisoning from swallowing coolant.	Do not open cooling system unless coolant temperature is below 90°C. Open cap slowly and release the pressure. Do not pour coolant into beverage containers. Wear protective gloves, protective clothing and safety glasses.	AS20.00-Z-0001-01A
1	Remove coolant thermostat (1)	Installation: Install new sealing ring. The coolant thermostat (1) must not be removed from the housing. Otherwise it will be destroyed. The housing is supplied together with the coolant thermostat (1) for repair purposes.	AR20.10-P-2460GZ
	Checking
2	Heat coolant thermostat (1)	Suspend coolant thermostat (1) from a wire in a vessel filled with water and heat the water. For heating up under no circumstance use a welding torch or a soldering torch, otherwise the sudden heat penetration modifies the metal structure!
3	Measure temperature of water	The heating-up rate should be not more than 1 to 2°C / minute from about 8°C below the start of opening of the coolant thermostat (1).
			*WH58.30-Z-1002-08A
4	Warm up water to full opening temperature of the valve (2) and then measure the hub of the valve (2)	If the test values are not achieved, replace coolant thermostat (1).
		Start of opening	*BE20.10-P-1001-02A
		Minimum stroke	*BE20.10-P-1002-02A
5	Install in the reverse order
6	Inspect cooling system for leaks		AR20.00-P-1010GZ
	Risk of accident caused by vehicle starting off by itself when engine is running. Risk of injury caused by contusions and burns during starting procedure or when working near the running engine	Secure vehicle to prevent it from moving by itself. Wear closed and snug-fitting work clothes. Do not grasp hot or rotating parts.	AS00.00-Z-0005-01A
7	Conduct engine test run and check the engine for leaks	In the event of oil loss determine and eliminate cause, otherwise malfunctions, transmission damage, and serious environmental pollution may occur.

COOLANT THERMOSTAT

Number	Designation		Engine 112, Engine 113.940/941/942/943/944/945/946/948/960/961/962/963/964/965/966/967/968/971/980/981/982/984/986/987/988/990/991/992/993/995
BE20.10-P-1001-02A	Start of opening	°C	85...89
BE20.10-P-1002-02A	Minimum stroke	°C	102
BE20.10-P-1002-02A	Minimum stroke	mm	8

COMMERCIALLY AVAILABLE TOOLS

Number	Designation
WH58.30-Z-1002-08A	Digital temperature measuring instrument (measuring range -20° to +70°)