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

ENGINE 642 in MODEL 164, 251 

ENGINE 629 in MODEL 164 

Fig 1: Inspecting Cooling System For Leaks

Courtesy of MERCEDES-BENZ USA

	Checking
	Risk of injury  caused by fingers being pinched or crushed  when removing, installing or aligning hoods, doors, trunk lids, tailgates 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
	Notes on coolant		AH20.00-N-2080-01A
	Notes on coolant level		AH20.00-P-1142-01GZB
1	Set heater switches to maximum heat output
2	Unscrew 2-stage cap from coolant expansion reservoir (1)	Turn 2-stage cap half a turn in an anti-clockwise direction, release pressure, and then unscrew 2-stage cap.
3	Check coolant level	If the antifreeze content of the coolant is too low, either add more antifreeze or replace the coolant: ↓ Drain/fill in coolant
		Engine 642	AR20.00-P-1142GZB
		Engine 629	AR20.00-P-1142GZD
	Coolant specifications	Specification	Coolant (Specification 310.1)
	Anticorrosion/antifreeze agents (Specification)	Specification	Anticorrosion/antifreeze agents (Specification 325.0)
4	Screw test cap (2) onto coolant expansion reservoir (1).		Fig 2
5	Attach pressure pump (3) to the test connection (2)		Fig 3
6	Pressurize cooling system	Test pressure not higher than 1.4 bar. If new cylinder head gasket fitted, first of all warm up engine to operating temperature before testing cooling system for leaks.
		Test pressure for pressure-testing cooling system	*BE20.30-P-1005-01A
7	Check hose clamps for condition and seating	If hose clamps are loose, tighten them or replace them.
8	Check coolant hoses and heater hoses and their connecting points for condition and coolant loss.	Replace damaged parts in order to prevent leaks.
9	Unscrew test cap (2) at coolant expansion reservoir (1).	Slowly unscrew test cap (2) and reduce excess pressure.
			Fig 2
10	Remove pressure pump (3) from test cap (2)		Fig 3
11	Close off expansion reservoir for coolant (1) using a 2-stage test cap
12	Move heater switch to starting position

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