Check cylinders for leaks

AR01.00-P-1300MNO

Check cylinders for leaks

20.03.2020

Engine

176, 177 in model 167

Shown on engine 176

1

Pressure loss tester

 Warning

Risk of injury to skin and eyes suffering scalding from contact with hot coolantspray. 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

 Warning

Risk of injury. Skin or eye injuries may result when handling hot or glowing objects.

Wear protective gloves, protective clothing and safety glasses, if necessary.

AS00.00-Z-0002-01A

 Warning

Risk of accident from vehicle starting off by itself when engine running. Risk of injury (bruises and burns) resulting from working on the engine while it is being started or when it is running.

Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.

AS00.00-Z-0005-01A

 Caution

Risk of injury to skin and eyes due to handling of engine oil. Risk of poisoning caused by swallowing engine oil

Wear protective gloves, protective clothing and safety glasses.
Do not fill engine oil into beverage containers.

AS18.00-Z-0001-01A

Topical note

Notes on avoiding damage through contamination and foreign objects

AH00.00-P-5000-01A



Remove

1

Warm up engine to normal operating temperature.

2

Switch off ignition and store transmitter key outside of transmission range (min. 2  m).

3

Remove spark plugs.



Engine 176 in model 167

AP15.10-P-1580C



Engine 177 in model 167

AP15.10-P-1580K

4

Remove cap of coolant expansion reservoir.

5

Unscrew oil filler cap.

6

Attach TDC detection device to the cylinder to be checked.

 Commercially available devices/tools
The TDC detection device

7.1

Remove pump unit for the front electrohydraulic suspension with connected lines from the front axle and secure against falling down.

Engine 176 in model 167
with code 489 (AIRMATIC)
with code 490 (Electrohydraulic suspension)

AR32.50-P-0047ME

7.2

Remove lower engine compartment linings.

Engine 176 in model 167
except code 490 (Electrohydraulic suspension)
Engine 177 in model 167

AR61.20-P-1105ME

8

Turn engine at the center bolt of the crankshaft in the direction of engine rotation until the piston of the cylinder to be checked is at top dead center(ignition TDC).

 Aid of helper required.

 Ring wrench

*177589000300

9

Remove TDC detection device from the cylinder to be checked.

 Commercially available devices/tools
The TDC detection device

10

Connect pressure loss tester(1) at cylinder to be checked.

AR01.00-P-1300-01MNL

 Screw-in fitting

*270589019100

 Pressure loss tester

*450589172100



Check

11

Apply compressed air to cylinder to be checked and read pressure loss from pressure loss tester(1).

 If the crankshaft turns, counterhold engine at the belt pulley of the crankshaft with the aid of a helper.

Cylinder leakage: permissible loss total indication

*BE01.00-P-1001-02Z

Cylinder leaktightness: Permissible losses at valves and cylinder head gasket

*BE01.00-P-1002-02Z

Cylinder leaktightness: Permissible losses at pistons and piston rings

*BE01.00-P-1003-02Z

12

Check other cylinders in firing order of engine.

AR01.00-P-1300-03MM



Install

13

Disconnect pressure loss tester(1).

 Pressure loss tester

*450589172100

14

Remove thread adapter.

 Screw-in fitting

*270589019100

15.1

Install pump unit of the front electrohydraulic suspension.

Engine 176 in model 167
with code 489 (AIRMATIC)
with code 490 (Electrohydraulic suspension)

AR32.50-P-0047ME

15.2

Install lower engine compartment linings.

Engine 176 in model 167
except code 490 (Electrohydraulic suspension)
Engine 177 in model 167

AR61.20-P-1105ME

16

Install oil filler cap.

17

Attach cap of coolant expansion reservoir.

18

Install spark plugs.



Engine 176 in model 167

AP15.10-P-1580C



Engine 177 in model 167

AP15.10-P-1580K

Cylinder leakage

Number

Designation

Engine all (4xWD, CAR, smart)

BE01.00-P-1001-02Z

Cylinder leakage: permissible loss total indication

%

 25

Cylinder leakage

Number

Designation

Engine all (4xWD, CAR, smart)

BE01.00-P-1002-02Z

Cylinder leaktightness: Permissible losses at valves and cylinder head gasket

%

 10

Cylinder leakage

Number

Designation

Engine all (4xWD, CAR, smart)

BE01.00-P-1003-02Z

Cylinder leaktightness: Permissible losses at pistons and piston rings

%

 20