Overhaul

Piston and connecting rod, component overview

Note:
^ Oil injector jet for piston cooling





1 - Connecting rod bolt - 30 Nm plus an additional 1/4 turn (90°)
^ Replace
^ Lubricate threads and contact surface
^ Tighten to 30 Nm to measure radial play, do not turn further

2 - Connecting rod bearing cap
^ Do not interchange
^ Mark allocation to cylinder using a color marker - B -.
^ When installing bearing cap, observe: The wide thrust flange - A - must point to same side on connecting rod and connecting rod bearing cap
^ 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)
^ Over-sized bearings are available for reworked crankshaft connecting rod journals

4 - Connecting rod
^ Only replace as set
^ Mark allocation to cylinder with paint - B -.
^ When installing bearing cap, observe: The wide thrust flange - A - must point to the same side on connecting rod and connecting rod bearing cap
^ Installation position of connecting rod pairs
^ Axial play for each new connecting rod pair: 0.20 to 0.38 mm
^ Axial play wear limit: 0.60 mm

5 - Piston pin
^ If tight, heat piston to 60° C
^ Removing and installing using a drift VW 222 A

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
^ Measuring end cap
^ Measuring side clearance





Measuring piston ring gap
- Push ring squarely from above down to approximately 15 mm from bottom end of cylinder. To do this use a piston without rings.








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








Checking piston
- Measure approximately 10 mm from the lower edge, at a 90° angle to piston pin axis using an external micrometer 75 to 100 mm.

^ Maximum deviation from nominal dimension: 0.04 mm.

Nominal dimension go to, Piston and cylinder dimensions.





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.

Nominal dimension go to, Piston and cylinder dimensions.





Piston installation position
- Mark allocation to cylinder on piston head using chalk or water-proof felt pen.

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.
^ 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 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 injector jet (opening pressure 2 to 2.4 bar positive pressure)
2. Bolts - 9 Nm. Insert using locking compound; locking compound