Remove/install piston

AR03.10-P-7021MFF

Remove/install piston

06.03.2020

Engine

654 in model 118, 177, 247

Modification notes

31.01.2020

Bolt, connecting rod bearing cap to connecting rod

BA03.10-P-1001-01Y

1

Piston

2

Connecting rod

3

Bolts

4

Connecting rod bearing cap

5

Retaining ring

6

Piston pin

7

Connecting rod bearing shell

8

Connecting rod bearing shell

 Warning

Risk of injury. Moving parts can pinch, crush or, in extreme cases even sever extremities.

No parts of the body or limbs should be within the operating area of mechanical components when moving components.

AS00.00-Z-0009-01A

 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

 Caution

Risk of injury caused by scraping or cutting body parts on sharp vehicle parts

Always wear protective gloves when working on or near sharp and non-deburred vehicle parts.
Deburr repair panels.

AS00.00-Z-0017-01A

Topical note

Notes on avoiding damage through contamination and foreign objects

AH00.00-P-5000-01A



Remove

1

Remove crankcase lower section.

AR01.40-P-3200MFF

2

Remove cylinder head.

AR01.30-P-5800MFF

3

Clean sealing surfaces of crankcase.


Do not use any sharp-edged tools or abrasive paper.
Otherwise, the sealing surfaces of the crankcase may be damaged.

Assembly cleaner

*BR00.45-Z-1028-04A

4

Carefully remove combustion residues at top-land zone of cylinder bores and blow out cylinder bores with compressed air.


There must not be any combustion residues remaining in the cylinder bores.
Any such residue could damage the pistons and piston rings.


Turn engine in direction of engine rotation only.
The timing chain will otherwise skip, causing engine damage.

 Cover the piston crowns; if necessary, place the pistons (1) on the bottom dead center (BDC).

5

Mark installation position of pistons (1) relative to respective cylinder.

6

Check piston crowns for existing direction arrows and/or color dots.

If stamped direction arrows and/or color dots are no longer visible on already used engine



Clean piston crowns.

Assembly cleaner

*BR00.45-Z-1028-04A

If direction arrows and/or color dots are still not visible,



Apply color dots and/or direction arrows opposite output end side.

7

Mark connecting rods (2) relative to respective cylinder.


Do not interchange connecting rods (2).
Engine damage can occur otherwise.

8

Apply markings (arrows) on the connecting rod bearing caps (4) and corresponding connecting rods (2).


Connecting rods (2) and connecting rod bearing caps (4) are cracked (broken). Do not interchange.
Dimensional accuracy is otherwise no longer ensured and engine damage will occur.

9

Remove screw/bolts (3).

10

Mark installation position of connecting rod bearing shells (8) in connecting rod bearing caps (4).


Do not interchange connecting rod bearing shells (8) and connecting rod bearing caps (4).
Engine damage can occur otherwise.

11

Remove connecting rod bearing caps (4) from connecting rods (2) and remove connecting rod bearing shells (8).

12

Remove pistons (1) with connecting rods (2) upwards out of crankcase.

13

Mark installation position of connecting rod bearing shells (7) relative to connecting rods (2).


Do not interchange connecting rod bearing shells (7) and connecting rods (2).
Engine damage can occur otherwise.

14

Remove connecting rod bearing shells (7).

15

Remove retaining rings (5).


Perform the work on a clean soft base.
Pistons (1) will otherwise be damaged.

16

Mark piston pins (6) and connecting rods (2) relative to pistons (1).

Only where pistons (1) are reused.


Do not interchange piston pins (6), connecting rods (2) and pistons (1).
Engine damage can occur otherwise.

17

Clamp connecting rods (2) with pistons (1) in vise.

 Use protective jaws.

18

Press piston pins (6) out of pistons (1).

19

Remove pistons (1) from connecting rods (2).

20

Remove connecting rods (2) from vise.

21

Clean all power unit components.


The power unit components must be absolutely free of soiling.
Engine damage can occur otherwise.

Assembly cleaner

*BR00.45-Z-1028-04A



Check

22

Check pistons (1), piston pins (6) and piston rings for wear and damage.

Where pistons (1) and piston rings are reused.

Notes on the assessment of pistons and piston rings

AH03.10-P-0001-04MN

If problems occur,



Replace pistons (1) and/or piston pins (6) and/or piston rings.

AR03.10-P-7311MFF

23

Check connecting rod bearing shells (7, 8) and connecting rod journal for wear and damage.

Notes on assessing wear on connecting rod bearings and connecting rod journals

AH03.10-P-0001-03MM

If problems occur,



Replace connecting rod bearing shells (7, 8) or crankshaft.

AR03.20-P-4351MFF

24

Check connecting rod bearing caps (4) and connecting rods (2) for bluish coloration, transverse score marks and notches.

If problems occur,



Replace connecting rod bearing caps (4) and connecting rods (2).

25

Check cylinder barrels for wear and damage.

General information on inspecting cylinder walls

AH01.00-P-0300-01AMG

If problems occur,



Replace crankcase.



Install

26

Clamp connecting rods (2) in vise.

 Use protective jaws.

27

Wet piston pins (6) and connecting rod small ends with engine oil.



Specified engine oils (service) - Overview

BB00.40-P-0223-02A

28.1

Assign new pistons (1), connecting rods (2) and piston pins (6) to each other.

Only where pistons (1) are replaced.

28.2

Assign previously marked pistons (1), connecting rods (2) and piston pins (6) to each other.

Only where pistons (1) are reused.


Note the applied markings during removal.
Engine damage can occur otherwise.

29

Manually press piston pins (6) into pistons (1) and connecting rods (2).

30

Install retaining rings (5).

 Replace retaining rings (5).

31

Remove connecting rods (2) with pistons (1) from vise.

32

Wet cylinder bores, connecting rod journals of crankshaft, pistons (1), connecting rod bearing shells (7, 8), connecting rods (2) and connecting rod bearing caps (4) with engine oil.



Specified engine oils (service) - Overview

BB00.40-P-0223-02A

33

Offset the piston ring end gaps of the piston rings by 120°.


The piston ring end gaps of the piston rings should be offset 120°.
Engine damage can occur otherwise.

34

Fit tensioning strap for piston rings on piston (1) and tension.

 Tensioning strap

*000589041400

35

Insert pistons (1) with connecting rods (2) into respective cylinder bore.


Observe color dots and/or travel direction arrows.
Engine damage can occur otherwise.

36

Press pistons (1) into respective cylinder bore.


Turn the crankshaft in the direction of engine rotation so that when the pistons (1) are placed in the cylinder bores, no connecting rods (2) come into contact with the connecting rod journals.
Otherwise damage will occur on the connecting rod (2) and crankshaft.

 Only press pistons (1) into cylinder bores to extent that  tensioning strap can be removed.

  Tensioning strap must always be supported on crankcase when pressing in pistons (1). If necessary reset the  tensioning strap.

 Tensioning strap

*000589041400

37.1

Install new connecting rod bearing shells (7, 8).

Only where connecting rod bearing shells (7, 8) are replaced.

AR03.10-P-6112-01OIB


Insert connecting rod bearing shells (7, 8) in non-canted manner into connecting rod bearing caps (4) and connecting rods (2).
Engine damage can occur otherwise.

37.2

Install previously marked connecting rod bearing shells (7, 8) at respectively marked location.

Only where connecting rod bearing shells (7, 8) are reused.


Insert the connecting rod bearing shells (7, 8) non-canted into the connecting rod bearing caps (4) and connecting rods (2).
Engine damage can occur otherwise.

38

Install connecting rod bearing caps (4) and associated connecting rods (2) on crankshaft according to applied markings (arrows).


Connecting rods (2) and connecting rod bearing caps (4) are cracked (broken). Do not interchange.
Dimensional accuracy is otherwise no longer ensured and engine damage will occur.

39

Wet the screws (3) on the thread and contact surface with engine oil.



Specified engine oils (service) - Overview

BB00.40-P-0223-02A

 Replace screw/bolts (3).

40

Tighten bolts(3).

Topical note

Notes on threaded connections fastened using a tightening angle-based tightening process

AH00.00-P-0020-01A

 Bolt, connecting rod bearing cap to connecting rod

*BA03.10-P-1001-01Y

41

Crank crankshaft by hand and check for unobstructed movement of crank assembly.


Turn engine in direction of engine rotation only.
Otherwise the timing chain jumps and causes engine damage.

If crankshaft only cranks sluggishly,



Check assignment and for correct seating of connecting rod bearing shells (7, 8) and connecting rod bearing caps (4).

42

Install cylinder head.

AR01.30-P-5800MFF

43

Install crankcase lower section.

AR01.40-P-3200MFF

 Connecting rod

Number

Designation

Engine 654

BA03.10-P-1001-01Y

Bolt, connecting rod bearing cap to connecting rod

For initial tightening after cracking

Stage 1

Nm

5

Stage 2

Nm

25

Stage 3

°

180

Stage 4

Loosen bolts

Stage 5

Nm

5

Stage 6

Nm

25

Stage 7

°

90

For subsequent tightening

Stage 1

Nm

5

Stage 2

Nm

25

Stage 3

°

90

Repair materials

Number

Designation

Order number

BR00.45-Z-1028-04A

Assembly cleaner

A 000 986 56 01