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

ENGINE 133 in MODEL 117, 156, 176 

Fig 1: Inspecting Cooling System For Leaks

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
	Remove
1	Switch on ignition
2	Adjust heater to maximum heat output
3	Unscrew cap (1) on coolant expansion reservoir (2)	Unscrew cap (1) slowly and relieve overpressure.
4	Check coolant level and antifreeze content coolant
	Notes on coolant level		AH20.00-P-1142-01CW
		If antifreeze content of coolant is too low, either antifreeze protection must be added or the coolant must be replaced. ↓ Drain/fill in coolant
			AR20.00-P-1142MTA
5	Screw on tester cap (3) at coolant expansion reservoir (2)	Test cap	Fig 3
6	Connect pressure pump (4) at tester cap (3)	Pressure pump	Fig 2
7	Apply test pressure to cooling system	Test pressure for pressure-testing the engine cooling system	*BE20.30-P-1005-01A
	Check
8	Perform a visual inspection on the components carrying coolant	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. Check condition and seating of the Henn coupling; replace safety springs if necessary in order to avoid coolant loss. ↓ Open and close coupling
			AR09.41-P-1311-01AL
	Install
9	Actuate pressure relief button on the pressure pump (4) and remove test pressure in cooling system
10	Detach pressure pump (4) from tester cap (3)
11	Unscrew tester cap (3) at coolant expansion reservoir (2)
12	Switch off ignition
13	Check coolant level
	Notes on coolant level		AH20.00-P-1142-01CW
14	Screw cap (1) onto coolant expansion reservoir (2)

RADIATOR OR EXPANSION RESERVOIR CAP

Number	Designation			1-stage cover latch	2-stage cover latch
BE20.30-P-1005-01A	Test pressure for pressure-testing the engine cooling system	Overpressure	bar	1, 4	1, 4

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

Courtesy of MERCEDES-BENZ USA

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

Courtesy of MERCEDES-BENZ USA