Remove/install piston rings

AR03.10-S-7311SE

Remove/install piston rings

06.03.2020

Engine

642 in model 470, 471

Engine

642 in model 639

Engine

642.896/898/992/993 in model 906

Modification notes

19.02.2019

Commercially available tools, added.

Operation steps 2, 7

1

Piston ring (compression ring)

2

Piston ring (compression ring)

3

Piston ring (oil scraper ring)

4

Garter spring

8

Hooked spring

10

Pliers

Measure vertical clearance

Measure end gap

 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

Notes on the assessment of pistons and piston rings

AH03.10-P-0001-04MN

 

Remove/install

1

Remove the piston.

AR03.10-S-7021SE

2

Determine the vertical clearance of the piston rings (1, 2, 3) using a feeler gauge.

 Commercially available devices/tools
Feeler gage

Engine 642 in model 470, 471
Engine 642 in model 639
Engine 642 in model 906Piston ring vertical clearance

*BE03.10-N-1003-02Q

If the vertical clearance is excessive,



Replace the piston and piston rings (1, 2, 3).

3

Remove piston rings (1, 2, 3) with pliers (10).

 Installation: Note the installation position of piston rings (1, 2, 3). The lettering "Top" or the name of the manufacturer must point toward the piston crown.

 Installation: Insert the hook spring (8) with the garter spring (4) with a 180° offset relative to the ring gap for the piston ring (3).
Install the piston rings (1, 2) with the ring gaps offset by 120°.

 Pliers

*000589513700



Clean

4

Clean the grooves in the piston rings (1, 2, 3) in the piston.

Assembly cleaner

*BR00.45-Z-1028-04A

5

Clean cylinder barrel.

Assembly cleaner

*BR00.45-Z-1028-04A



Check

6

Check the piston rings (1, 2, 3) for damage / chippings on the coating.

If there is a problem,



Replace the piston ring (1, 2, 3).

7

Check end gap of the piston rings (1, 2, 3) with a feeler gauge.

 Commercially available devices/tools
Feeler gage

 Insert the relevant piston ring (1, 2, 3) in the unused area of the cylinder barrel.

Engine 642 in model 470, 471
Engine 642 in model 639
Engine 642 in model 906Piston ring end gap

*BE03.10-N-1004-02Q

If the end gap is excessive,



Replace the piston ring (1, 2, 3).

8

Install in the reverse order.

Test specifications for pistons

Number

Designation

Engine 642 in model 470, 471

Engine 642 in model 639

BE03.10-N-1003-02Q

Piston ring vertical clearance

Groove 1

mm

0,12...0,16

0,12...0,16

Groove 2

mm

0,12...0,16

0,12...0,16

Groove 3

mm

0,03...0,07

0,03...0,07

Test specifications for pistons

Number

Designation

Engine 642 in model 906, 907

BE03.10-N-1003-02Q

Piston ring vertical clearance

Groove 1

mm

0,18...0,24

Groove 2

mm

0,05...0,10

Groove 3

mm

0,03...0,07

Test specifications for pistons

Number

Designation

Engine 642 in model 470, 471

Engine 642 in model 639

BE03.10-N-1004-02Q

Piston ring end gap

Groove 1

mm

0,40...0,55

0,40...0,55

Groove 2

mm

0,25...0,50

0,25...0,50

Groove 3

mm

0,20...0,40

0,20...0,40

Test specifications for pistons

Number

Designation

Engine 642 in model 906, 907

BE03.10-N-1004-02Q

Piston ring end gap

Groove 1

mm

0,20...0,40

Groove 2

mm

0,40...0,60

Groove 3

mm

0,20...0,40

Repair materials

Number

Designation

Order number

BR00.45-Z-1028-04A

Assembly cleaner

A 000 986 56 01