Piston and Connecting Rod, Assembly Overview
Assembly overview
Gradual introduction of industrially cracked connecting rods
Piston with conventional connecting rod
Piston with industrially cracked connecting rod
Gradual introduction of industrially cracked connecting rods
Identification:
A - conventional connecting rods with polished parting surfaces
B - industrially cracked connecting rods with rough parting surfaces
Piston with conventional connecting rod
Piston with industrially cracked connecting rod
Piston with conventional connecting rod
Note:
^ When working on the engine, it should be secured with the Holding fixture VW540 and the Spacers VW 540/1 B to the support clamp.
1 - Piston rings
^ Gaps offset by 120°
^ Remove and install using piston ring pliers
^ "TOP" faces piston crown
2 - Piston
^ Mark installation position and cylinder number
^ Arrow on piston crown points to belt pulley end Install using piston ring clamp
3 - Connecting rod
^ Replace as set only
^ Mark cylinder number - B -
^ Installation position: Marking - A - faces belt pulley end
4 - Connecting rod bearing cap
^ Mark cylinder number - B -
^ Installation position: Marking - A - faces belt pulley end
5 - 30 Nm plus 1/4 turn (90°)
^ Replace
^ Oil threads and contact surfaces
^ To measure radial clearance, tighten to 30 Nm, but do not turn further
6 - Pressure relieve valve, 27 Nm
7 - Oil spray jet
^ For piston cooling
8 - Bearing shell
^ Note installed position
^ Do not interchange used bearing shells
^ Ensure retaining lugs fit tightly in recesses
^ Upper bearing shell with oil drilling for piston pin lubrication
^ Axial clearance
- New: 0.05 to 0.31 mm
- Wear limit: 0.37 mm
^ Check radial clearance with Plastigage:
- New: 0.01 to 0.06 mm
- Wear limit: 0.12 mm
^ Do not rotate crankshaft when checking radial clearance
9 - Cylinder block
10 - Connecting rod bolt
11 - Circlip
12 - Piston pin
^ If difficult to remove, heat piston to 60°C
^ Remove and install with VW 222 A
Checking piston ring gap
Special tools, testers and auxiliary items required
^ Feeler gauges
Work sequence
- Push ring squarely from above down to approx. 15 mm from bottom end of cylinder.
Checking piston ring gap
Special tools, testers and auxiliary items required
^ Feeler gauges
Work sequence
- Clean groove before check.
Checking piston
Special tools, testers and auxiliary items required
^ External micrometer 75 to 100 mm
Work sequence
- Measure pistons approx. 10 mm from the lower edge of skirt, at 90° to the piston pin axis.
- Difference between actual and nominal diameter: not more than 0.04 mm
Checking cylinder bores
Special tools, testers and auxiliary items required
Internal dial gauge 50100 mm
- Take measurements at 3 positions in both lateral - A - and longitudinal - B - planes, as illustrated.
- Difference between actual and nominal diameter: not more than 0.08 mm
Note:
^ Measuring the cylinder bores must not be done when the cylinder block is mounted on a repair stand with holding fixture VW540 and spacers VW 540/1 B, as incorrect measurements would then be possible.
Piston with industrially cracked connecting rod
Note:
^ When working on the engine, it should be secured with the Holding fixture VW540 and the Spacers VW 540/1 B to the support clamp.
1 - Piston rings
^ Gaps offset by 120°
^ Remove and install using piston ring pliers
^ "TOP" faces piston crown
2 - Piston
^ Mark with installation position and cylinder number
^ Arrow on piston crown points to belt pulley end
^ Install using piston ring clamp
3 - Piston pin
^ If difficult to remove, heat piston to 60°C
^ Remove and install with VW 222 A.
4 - Circlip
5 - Connecting rod
^ With industrially cracked bearing caps
^ Replace as set only
^ Mark with cylinder number - B -
^ Installation position: Marking - A - faces belt pulley end
6 - Bearing shell
^ Note installed position.
^ Insert bearing shells centrally
^ Do not interchange used bearing shells
^ Check for secure seating
^ Axial clearance
- New: 0.10 to 0.35 mm
- Wear limit: 0.4 mm
^ Check radial clearance with Plastigage:
- New: 0.01 to 0.05 mm
- Wear limit: 0.09 mm
^ Do not rotate crankshaft when checking radial clearance
7 - Cylinder block
8 - Connecting rod bearing cap
^ Note installed position
^ Caps only fit in one position and only on appropriate connecting rod due to breaking procedure (cracking) separating cap from connecting rod
9 - Oil spray jet
^ For piston cooling
10 - Pressure relieve valve, 27 Nm
11 - 30 Nm plus 1/4 turn (90°)
^ Replace
^ Oil threads and contact surfaces
^ To measure radial clearance, tighten to 30 Nm, but do not turn further
Checking piston ring gap
Special tools, testers and auxiliary items required
^ Feeler gauges
Work sequence
- Push ring squarely from above down to approx. 15 mm from bottom end of cylinder.
Checking piston ring gap
Special tools, testers and auxiliary items required
^ Feeler gauges
Work sequence
- Clean groove before check.
Checking piston
Special tools, testers and auxiliary items required
^ External micrometer 75 to 100 mm
Work sequence
- Measure pistons approx. 10 mm from lower edge of skirt, at 90° to piston pin axis.
- Difference between actual and nominal diameter: not more than 0.04 mm
Installation position of bearing shells
Bearing shell - 1 - with oil drilling - arrow - for connecting rod.
Bearing shell - 2 - with no oil drilling for connecting rod bearing cap.
- Insert bearing shells centralized in connecting rod and connecting rod bearing cap.
- Dimension - a - must be same on left and right sides.
Checking cylinder bores
Special tools, testers and auxiliary items required
^ Internal dial gauge 50 to 100 mm
- Take measurements at 3 positions in both lateral - A - and longitudinal - B - planes, as illustrated.
- Difference between actual and nominal diameter: not more than 0.08 mm
Note:
^ Measuring the cylinder bores must not be done when the cylinder block is mounted on a repair stand with holding fixture VW540 and spacers VW 540/1 B, as incorrect measurements would then be possible.