Piston: Service and Repair

REMOVING AND INSTALLING / REPLACING ALL PISTONS (M60)

(Engine Removed)

Removal

Removal of pistons is described separately from installation. Assembly sequence for removal and installation is different.

Remove both cylinder heads. Service and Repair

Remove upper section of oil pan. Service and Repair

Remove oil pump. Service and Repair

Caution!
- Re-install piston, connecting rod and bearing shells back in the same position and in the same installation location.
- Conrod and conrod bearing cover are designated with same pair number: do not interchange / confuse.




Remove connecting-rod cover.




Insert special tool 11 2 470 in conrod. Remove connecting rod with piston from cylinder-head side.




Lift out retaining ring and press out piston pin.

Important! Piston and piston pin are paired and must not be fitted individually.

Installation
Installation of pistons is described separately from removal. Assembly sequence for removal and installation is different.




If necessary, replace connecting rods.

Note: The conrods can also be replaced individually.

It should be possible to press piston pin into bush by hand using only slight pressure. Clearance should then be minimal.




Before installation, measure piston installation clearance. Measure piston diameter with micrometer at measuring point A from bottom edge of piston and offset at 90° to the axis of the piston pin.




Adjust micrometer on cylinder bore of engine block and set plug gauge on micrometer to zero. Measure bottom, centre and top of cylinder bore in direction of travel and direction of engine rotation.




Install conrod bearing. Service and Repair

Important! Piston and piston pin are paired and must not be fitted individually.

Fit connecting rod with piston pin to piston in such a way that, with the pair number visible, the installation direction arrow on the piston points to the right.




Install retaining ring.




Install special tool 11 2 470 in conrod.




Lightly coat pistons and piston rings with oil. Align contact points of piston rings (offset at approx. 120°, but not over piston pin lug).

Press together piston rings using special tool 11 2 260.




Install pistons with arrows pointing towards camshaft drive.

The tightening strap must locate firmly right around circumference of engine block.

Important!
- Danger of piston ring failure.
- Only press pistons into place with finger force - do not knock in!




Attach crankpin to connecting rod.




Apply light coat of oil to connecting-rod bearing shells

Place bearing caps in position, making sure that matching numbers are paired.

Install new connecting-rod screws.




Tighten down conrod bearing with special tool 00 9 120 or 11 2 110.

Tightening torque, Application torque = 5 Nm
Jointing torque = 20 Nm
Torque angle = 80°