Piston and Connecting Rod, Assembly Overview

Piston and connecting rod, assembly overview

Note:
^ Oil injector jet for piston cooling





1 - Connecting rod bolt, 40 Nm plus an additional 90° (1/4 turn)
^ Replace
^ Lubricate threads and contact surface
^ Tighten to 40 Nm to measure radial play, do not turn further

2 - Connecting rod bearing cap
^ Do not interchange
^ Mark affiliation to cylinder with paint
^ Installation position of connecting rod pairs

3 - Bearing shells
^ Check that retaining tabs are secured
^ Do not interchange used bearing shells (mark, but not on running surface)
^ To measure radial play, tighten bolt - 1 - to 40 Nm but no further
^ Over-sized bearings are available for reworked crankshaft connecting rod journals
^ Insert bearing shells with correct color marking

4 - Connecting rod
^ Only replace as set
^ Mark affiliation to cylinder with paint
^ Installation position of connecting rod pairs
^ Axial play for each new connecting rod pair: 0.20 to 0.27 mm
^ Axial play wear limit: 0.30 mm
^ Insert connecting rod with correct identification letter

5 - Piston pin
^ If tight, heat piston to 60° C

6 - Circlip
7 - Piston
^ Installation position of pistons
^ Checking
^ Install with piston ring compressor
^ Measuring cylinder bore

8 - Piston rings
^ Offset gaps by 120°
^ Use piston ring pliers for removal and installation
^ "TOP" marking or inscribed side must point to piston head
^ Gap, measuring
^ Measuring side clearance





Piston ring end gap, measuring
- Slide piston ring down from above at a right angle to cylinder wall until it is approximately 15 mm from bottom edge of cylinder.
- When sliding in, use a piston without piston rings.








Measuring piston ring side clearance
- Clean ring groove of piston before checking.








Checking piston
- Measure approximately 15 mm from lower edge, at a 90° angle to piston pin axis using an external micrometer 75 to 100 mm.

^ Maximum deviation from nominal dimension: 0.03 mm.





Measuring cylinder bore
- Using an internal dial gauge 50 to 100 mm, measure at 3 points in diagonal sequence horizontally - A - and vertically - B -.

^ Maximum deviation from nominal dimension: 0.08 mm.





Piston installation position
- Identify allocation to cylinder with paint on piston crown.

Note:
^ Do not use a center punch or scribe, since the piston head coating will be damaged.

Installed location:
^ Arrows on piston heads point to belt pulley side.
^ Large valve recesses - 1 - point toward center of engine.





Mark connecting rod

Note:
^ Only replace connecting rod as a set.
^ Do not interchange connecting rod bearings.

- Before removing, mark allocation of connecting rod and connecting rod bearing caps to each other and to cylinder with paint - arrow -.





Connecting rod, installed location
^ Molded tabs - arrows - at beveled surfaces of the connecting rod pairs 1 and 2, 3 and 4, 5 and 6 as well as 7 and 8 must point toward each other.





Oil spray jet for piston cooling
1. Oil spray jet
2. Bolts, 9 Nm. Insert using locking compound.

CAUTION!
^ Do not bend piston spray nozzles.
^ Bend piston spray nozzles must be replaced.