Inspect cooling system for leaks - AR20.00-P-1010LF

MODEL 217 with ENGINE 157, 276, 278, 279 

MODEL 222 with ENGINE 157, 276.8/9, 277, 278, 279, 642, 651 

Shown on engine 278 

Fig 1: Inspecting Cooling System For Leaks - Shown On Engine 278

Courtesy of MERCEDES-BENZ USA

	Risk of injury  to skin and eyes suffering 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
	Notes on coolant		AH20.00-N-2080-01A
	Notes on coolant level		AH20.00-P-1142-01LFB
	Notes on coolant level		AH20.00-P-1142-01MUB
	Remove
1	Switch on ignition
2	Adjust heater to maximum heat output
4	Unscrew cap (1) slowly on coolant expansion reservoir (2) and reduce overpressure
5	Check coolant level and antifreeze content of coolant; correct if necessary	ENGINE 651 Cooling system	*BF20.00-P-1001-02KA
		ENGINE 642, low temperature circuit Cooling system for low temperature circuit	*BF20.00-P-1002-02HA
		ENGINE 642, high temperature circuit Cooling system for high-temperature circuit	*BF20.00-P-1001-02HA
		ENGINE 157, 276.8/9, 277, 278, 279 Coolant mixing ratio	*BF20.00-P-1001-04A
6	Screw tester cap (3) onto coolant expansion reservoir (2).	Test cap	Fig 3
7	Connect pressure pump (4) at tester cap (3)	Pressure pump	Fig 2
8	Apply a test pressure to the engine cooling system	The specified test pressure must not be exceeded. Damage will occur to the engine cooling system otherwise. Test pressure for pressure-testing the engine cooling system	*BE20.30-P-1005-01A
9	Check condition and coolant loss for all coolant carrying components and connections	There is the possibility, for example, that coolant can find its way over a defective cylinder head gasket into the combustion chamber or over a defective water heat exchanger into the oil circuits.
		If there is no external coolant loss recognizable. ↓ Check coolant carrying components for inner leaktightness
10	Relieve overpressure over the pressure relief button on the pressure pump (4) and remove pressure pump (4)	To do this actuate pressure relief button on the pressure pump (4). Pressure pump	Fig 2
11	Screw tester cap (3) onto coolant expansion reservoir (2)	Test cap	Fig 3
12	Switch off ignition and remove transmitter key
13	Screw cap (1) onto coolant expansion reservoir (2)

Fig 2: Identifying Pressure Pump (124 589 24 21 00)

Courtesy of MERCEDES-BENZ USA

Fig 3: Identifying Test Cap (210 589 00 91 00)

Courtesy of MERCEDES-BENZ USA