Remove/install piston rings · ar0310w7311a · Mercedes-Benz WIS

AR03.10-W-7311A

Remove/install piston rings

3.8.11

ENGINE 902.9 in MODEL 957 with CODE (MS8) Natural gas engine

ENGINE 904.904 in MODEL 670

ENGINE 904.908 /914 /923 /936 in MODEL 668, 670

ENGINE 904.9 in MODEL 374, 375, 673, 674, 676, 958, 970, 972, 975, 976

ENGINE 906.9 in MODEL 374, 958, 970, 972, 974, 975, 976

ENGINE 906.9 in MODEL 374, 375, 950, 952, 953, 954, 957, 958

W03.10-1037-06

1 Piston ring (keystone ring)

2 Piston ring (taper-faced ring with inside angle)

3 Piston ring (bevel-edged ring with spring expander)

3.1 Coil spring

4 Piston

5  Pliers

5.1  Knurled screw

A Spring expander offset

B Spread value

	Removing
1	Remove piston (4)		AR03.10-W-7021A
2	Remove combustion residues on piston rings (1, 2, 3)
3	Clamp connecting rod and piston (4) in a vise
4	Adjust pliers (5) using a knurled screw (5.1)	 Set to max. permissible spread value (B) before disassembling piston ring (1, 2, 3).	*BE03.10-N-1002-05B
			*000589373700
5	Remove piston rings (1, 2, 3) in order from top to bottom		*000589373700
6	Check piston rings (1, 2, 3) for chippings on coating	 Replace the related piston ring (1, 2, 3) if necessary.
7	Measure piston ring gap clearance of piston rings (1, 2, 3)	 Remove spring expander (3.1) on piston ring (3) and piston ring (1, 2, 3) in unworn area above reversal point of 1st piston ring, place in cylinder barrel and measure end gap.	*BE03.10-N-1001-05B
		Replace the related piston ring (1, 2, 3) if necessary.
	Install
8	Install spring expander (3.1) in piston ring (3).	 Installation position of spring expander offset (A) from coil spring end gap (arrow) to piston ring end gap must be offset by about 180°.
9	Adjust pliers (5) using a knurled screw (5.1)	 Set to max. permissible spread value (B) before assembling the piston ring (1, 2, 3).	*BE03.10-N-1002-05B
			*000589373700
10	Install piston rings (1, 2, 3) in the order from bottom to top	 Observe correct installation position. The marking "TOP" must point toward piston crown. Installation position of spring expander offset (A) from coil spring end gap (arrow) to piston ring end gap must be offset by about 180°.
			*000589373700
11	After installing piston rings (1, 2, 3), check for chipping of the surface coating	 Replace the related piston ring (1, 2, 3) if necessary.
12	Install piston (4)		AR03.10-W-7021A

Check values for piston rings

Number	Designation				Engine 900.9, 902.9, 904.9, 906.9


BE03.10-N-1001-05B	Piston ring end clearance	Groove I Keystone ring	New	mm	0.35...0.55
			Service limit	mm	1.0
		Groove II Taper-faced ring with internal angle	New	mm	0.40 to 0.60
			Service limit	mm	1.0
		Groove III Bevel-edge ring with garter spring	New	mm	0.25 to 0.50
			Service limit	mm	1.0
BE03.10-N-1002-05B	Expanding value of piston ring		max.	mm	43

000 589 37 37 00

Pliers

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ar0310w7021a