Removal and Replacement
Pistons and Connecting Rod Overview
1 Piston Rings
• Offset the gaps by 120°.
• Use piston ring pliers for removal and installation.
• "TOP" faces toward the piston crown.
• Checking the ring gap, refer to => [ Piston Ring Gap, Checking ].
• Checking the piston ring groove clearance, refer to => [ Piston Ring Groove Clearance, Checking ].
• Upper and center rings: compression rings,
• Lower ring: oil scraping ring,
2 Piston
• With the combustion chamber.
• Mark with the installed position and the cylinder allocation.
• Installed position and allocation, refer to => [ Piston Installed Position and Piston/Cylinder Allocation ].
• The arrow on the piston face points toward the belt pulley side.
• Install with a piston ring compressor.
• Replace if the piston skirt is cracked.
• Check the piston projection in Top Dead Center (TDC). Refer to => [ Piston Projection in TDC, Checking ] Testing and Inspection.
3 Piston Pin
• If difficult to move, heat the piston to 60 °C (140 °F).
• Remove and install using a pilot drift (VW 222).
4 Lock Ring
5 Connecting Rod
• Mark the allocation to the cylinder using a colored mark - A -
• Installed position: Marks - B - point to the belt pulley side.
• With a cracked bearing cap.
• Separating the new connecting rod. Refer to => [ New Connecting Rod, Separating ] Procedures.
6 Bearing Shell
• Note the installed position. Refer to => [ Connecting Rod Bearing Shell Installed Position ].
• Note the version: The upper bearing shell (to the piston) is made of wear resistant material, identification: Black line on the contact surface in the area of the separating point.
• Do not interchange used bearing shells (mark them).
• Insert bearing shells in the center,
• Make sure it is secure.
• Axial play:
Wear limit: 0.37 mm
• Measure radial clearance using Plastigage(R):
Wear limit: 0.08 mm
• Do not rotate the crankshaft when checking radial clearance.
7 Cylinder Block
• Checking the cylinder bore, refer to => [ Cylinder Bore, Checking ].
• For the correct piston and cylinder dimensions, refer to => [ Piston and Cylinder Dimensions ] [1][2]Specifications.
8 Connecting Rod Bearing Cap
• Pay attention to the installed position.
• Due to the separation procedure (cracking) of the connecting rod, the cap only fits in one position and only to the corresponding connecting rod.
9 Oil Spray Jet
• For piston cooling.
10 Bolt
• 25 Nm
• Install without sealant.
11 Bolt
• 30 Nm + an additional 90° (1/4) turn.
• Always replace.
• Lubricate the threads and contact surface.
• Use an old bolt to measure radial play.
Piston Ring Gap, Checking
Special tools, testers and auxiliary items required
• Feeler Gauge
- Insert the piston ring into the lower cylinder bore at a right angle from above, approximately 15 mm from the cylinder edge.
Piston Ring Groove Clearance, Checking
Special tools, testers and auxiliary items required
• Feeler Gauge
- Clean the ring groove before checking.
Cylinder Bore, Checking
Special tools, testers and auxiliary items required
• Internal Dial Gauge, 50-100 mm
- Measure diagonally at 3 positions transversely - A - and longitudinally - B -.
• Deviation from nominal size: Max. 0.10 mm.
• The cylinder bore must not be measured when the cylinder block is mounted on the engine and transmission holder (VAS 6095) because the measurements may be incorrect.
Piston, Checking
- Measure approximately 15 mm from the lower edge at a 90° angle to the piston pin axis using a 75 to 100 mm external micrometer.
• Maximum deviation from nominal dimension: 0.04 mm.
Nominal dimension, refer to => [ Piston and Cylinder Dimensions ] [1][2]Specifications.
• Replace the piston if there are cracks on the piston shaft.
Piston Installed Position and Piston/Cylinder Allocation
The arrow - arrows - on the piston crown faces cylinder 1.
Connecting Rod Bearing Shell Installed Position
Bearing shell - 1 - with connecting rod oil bore - arrow -.
Bearing shell - 2 - without oil bore for connecting rod cover.
- Place the bearing shells centrally into the connecting rod and connecting rod bearing cap.
Dimension - a - must be the same at left and right.