Inspecting cooling system for leaks - AR20.00-P-1010RK

ENGINES 157, 276, 278 in MODEL 231 

Shown on engine 276 

Fig 1: Inspecting Cooling System For Leaks - Shown On Engine 276

Courtesy of MERCEDES-BENZ USA

	Removing
	Risk of injury  caused by fingers being pinched or crushed  when removing, installing or aligning hoods, doors, trunk lids, liftgates or sliding roof	Keep body parts and limbs well clear of moving parts.	AS00.00-Z-0011-01A
	Risk of injury  to skin and eyes caused by scalding from contact with hot coolant spray. Risk of poisoning  caused by 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	Switch on ignition
2	Adjust heater to maximum heat output
3	Unscrew cap (1) from coolant expansion reservoir (2)	Unscrew cap (1) slowly and relieve overpressure.
4	Check coolant level and antifreeze content coolant	If antifreeze content of coolant is too small, either antifreeze protection must be added or the coolant must be replaced.
	Notes on coolant		AH20.00-N-2080-01A
5	Screw on test cap (3) at coolant expansion reservoir (2)	Test cap	Fig 2
6	Connect pressure pump (4) at tester cap (3)	Pressure pump	Fig 3
		Test cap	Fig 2
7	Apply test pressure to cooling system	The specified test pressure must not be exceeded. To avoid any damage to the cooling system.	*BE20.30-P-1005-01A
	Checking
8	Check condition and seating of the Henn coupling.	Replace catch springs if necessary.	AR09.41-P-1311-01AL
9	Perform visual inspection on coolant carrying components	Check condition and coolant loss for all coolant carrying components and connections. The coolant carrying components should be checked for inner leaktightness if there is no external coolant loss. 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.
	Install
10	Relieve test pressure in cooling system	To do this actuate pressure relief button on the pressure pump (4) Pressure pump	Fig 3
11	Remove pressure pump (4) from tester cap (3)
12	Unscrew tester cap (3) from coolant expansion reservoir (2)
13	Switch off ignition
14	Check coolant level and antifreeze content coolant	Mixture ratio for coolant	*BF20.00-P-1001-04A
	Notes on coolant		AH20.00-N-2080-01A
	Notes on coolant level		AH20.00-P-1142-01V
15	Screw cap (1) onto coolant expansion reservoir (2)

Fig 2: Identifying Test Cap (210 589 00 91 00)

Courtesy of MERCEDES-BENZ USA

Fig 3: Identifying Pressure Pump (124 589 24 21 00)

Courtesy of MERCEDES-BENZ USA