Remove/install cylinder head

AR01.30-G-5800DE

Remove/install cylinder head

17.09.2019

Engine

902.90 in model 000.001

Engine

906.90 in model 000.001

1

Charge air manifold

2

Rocker arm assembly

3

Push rod

4

Connection piece (cooling for automatic transmission version)

5

Seal

6

Connection fitting

7

Exhaust manifold with exhaust gas turbocharger

8

Cylinder head

9

Cylinder head bolt

10

Lifting eye

11

Cylinder head seal

12

Centering sleeve

13

Coolant line (compressor)

14

Engine start/stop button

8

Cylinder head

14

Lifting device

L

Shank length

9

Cylinder head bolt

15

Straightedge

 Danger

Risk of explosion due to escaping combustible gas or overheating of gas cylinders.Risk of injury caused by burns to skin and eyes. Risk of frostbite to body parts caused by escaping gas and by touching components near the valves when emptying gas cylinders. Risk of poisoning or suffocation caused by inhaling gas.

Remove any sources of ignition.
Protective clothing, safety gloves and safety glasses must always be worn.
Ensure that the work area is adequately ventilated.
When working on vehicles at ambient temperatures over 60 °C, all gas cylinders must be removed.

AS00.00-Z-0018-01A

 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

 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

 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 self-locking nuts and bolts

AH00.00-N-0001-01A

Topical note

Notes on avoiding damage through contamination and foreign objects

AH00.00-N-5000-01H

Notes on work safety regulations for vehicles with natural gas-powered engines

AH00.10-N-1000-04A

 

Remove/install

1

Close gas shutoff valves on compressed-gas tanks.

 See information from body manufacturer.

2

Start the engine and allow to run in idle until the engine stops by itself.

 See information from body manufacturer. In this way the residual gas from the lines and assembly parts is consumed.

3

Switch off ignition.

4

Drain the coolant and collect in a suitable container.

Drain/pour in coolant

AR20.00-G-1142DD

 Installation: See information from body manufacturer.

5

Remove charge air manifold (1).

AR09.41-G-8681DE

6

Remove rocker arm assembly (2).

Only engine 906.90 in model 000.001

AR05.00-G-5521DD

7

Remove push rods (3).

 Installation: Ensure that push rods (3) are seated correctly in the tappets.

8

Remove exhaust manifold with exhaust gas turbocharger (7) from cylinder head (8).

AR14.10-G-3915DE

9

Remove connection piece (4) between the coolant pump and cylinder head (8).

AR20.10-G-1290-02DF

 Installation: Replace connection fitting (6) and seal (5).

 Bolt, coolant pump connection piece to cylinder head

*BA20.10-N-1003-01L

10

Remove bracket with engine start/stop button (14) from cylinder head (8).

11

Remove coolant line (13) from cylinder head (8).

Collect coolant which flows out.

 Installation: Install new sealing rings.

12

Remove rear lifting eye (10).

13

Remove cylinder head bolts (9).

Tightening specifications for cylinder head bolts

AR01.30-W-5800-07A

 Installation: Observe tightening specifications for cylinder head bolts (9).

 Cylinder head bolts on crankcase

*BA01.30-N-1002-01L

 Socket wrench bit

*422589020900

14

Lift cylinder head (8) off of the crankcase with lifting device (14).


Do not set down cylinder head (8) on cylinder head contact surface
to avoid damaging the installed spark plugs.

 Lifting device

*904589016300

15

Remove cylinder head gasket (11).

 Installation: Replace cylinder head gasket (11). Observe the installation position relative to pilot bushing (12).



Check

16

Clean and check crankcase sealing surface and cylinder head contact surface.

Crankcase flatness of separating surface

*BE01.40-N-1009-02J

17

Clean thread, oil, and coolant bores in the crankcase.

18

Measure shank length (L) of cylinder head bolts (9).

 If max. shank length (L) was exceeded, corresponding cylinder head bolt (9) must be replaced.

Cylinder head bolts

*BE01.30-N-1001-01I

19

Check cylinder head sealing surface and cylinder head gasket (11).

AR01.30-W-5800-15B

 Check cylinder head (8) for cracks and damage, and use straightedge (15) to check for flatness; replace cylinder head (8) if necessary.

Height of cylinder head

*BE01.30-N-1001-02L

Permissible variation in flatness of lower separating surface in a longitudinal direction

*BE01.30-N-1002-02L

20

Install in the reverse order

21

Check coolant level; correct if necessary.

 See information from body manufacturer.

22

Start engine and perform an engine test run.

 Start engine with starter for max. 90 s. Wait at least for about 2 minutes before repeating attempt at starting. Do not rev up the engine as long as no oil pressure is displayed. An oil pressure must be indicated after about 10 s.

Engine oil pressure

*BE18.00-N-1001-01I

23

Switch off engine and check area of the cylinder head (1) for leak tightness.

Perform visual inspection.

Check values for cylinder head bolts

Number

Designation

Engine 900.9, 902.9, 904.9, 906.9, 924.9, 925.9, 926.9 in model 000.001

BE01.30-N-1001-01I

Cylinder head bolts

Thread diameter

M

16x2

Length of shank when new

mm

149,0

Permissible shank length

mm

151,0

Check values for cylinder head

Number

Designation

ENGINE 902.9, 906.9

BE01.30-N-1001-02L

Height of cylinder head

New

mm

107,9...108,1

after stock removal

mm

106,9

Check values for cylinder head

Number

Designation

ENGINE 902.9, 906.9

BE01.30-N-1002-02L

Permissible variation in flatness of lower separating surface in a longitudinal direction

over the entire length

mm

0,07

Over a length of 150 mm

mm

0,02

Check values for cylinder crankcase

Number

Designation

Engine 900.9## ## up to 185258, 902.9## ## up to 185258 in model 000.001

Engine 900.9## ## as of 185259, 902.9## ## as of 185259 in model 000.001

BE01.40-N-1009-02J

Crankcase flatness of separating surface

over the entire length

mm

0,030

0,030

Over a length of 150 mm in longitudinal or Transverse direction

mm

0,015

0,015

Check values for cylinder crankcase

Number

Designation

Engine 906.90# ## up to 185258 in model 000.001

Engine 906.90# ## as of 185259 in model 000.001

BE01.40-N-1009-02J

Crankcase flatness of separating surface

over the entire length

mm

0,030

0,030

Over a length of 150 mm in longitudinal or Transverse direction

mm

0,015

0,015

Test specifications for engine oil pressure

Number

Designation

Engine 900.9, 902.9, 904.9, 906.9

BE18.00-N-1001-01I

Engine oil pressure

idle speed

bar

0,5

maximum speed

bar

2,5

 Cylinder head

Number

Designation

Engine 900.9, 902.9, 904.9, 906.9 (except 906.901/902) in model 000.001

Engine 906.901/902 in model 000.001

BA01.30-N-1002-01L

Cylinder head bolts on crankcase

Stage 1

Nm

20

20

Stage 2

Nm

70

70

Stage 3

Nm

170

170

Stage 4

Nm

280

280

Stage 5

°

90

90

Stage 6

°

90

90

 Coolant pump, coolant thermostat

Number

Designation

Engine 900.9, 902.9, 904.9, 906.9 in model 000.001

BA20.10-N-1003-01L

Bolt, coolant pump connection piece to cylinder head

Nm

50