Connecting Rod: Service and Repair
Pistons and Connecting Rod Overview
1 Bolts
• Replace
• 50 Nm plus an additional 90° turn
• Lubricate the threads and contact surface
2 Connecting Rod Bearing Cap
• Mark for installation later
• Mark affiliation to cylinder with paint.
3 Bearing Shells
• Check that retaining tabs are secured
• Replace any worn bearing shells
• Over-sized bearings are available for reworked crankshaft connecting rod journals, refer to the electronic parts catalog ETKA
4 Connecting Rod
• Only replace as set
• Mark affiliation to cylinder with paint, refer to => [ Mark Connecting Rod ]
• Axial play for each new connecting rod pair: 0.16 to 0.40 mm
• Radial clearance, measuring, refer to => [ Connecting Rod, Measuring Radial Clearance ] Testing and Inspection
5 Circlip
• 2 pieces
• Replace
6 Piston Pin
• Heat piston to 60 °C (140 °F) if it is difficult to move.
• Removing and installing using a pilot drift (VW 222 A)
7 Piston
• Installed location, refer to => [ Piston Installed Position ]
• Replace the piston if there are cracks on the piston head or piston shaft
• Checking, refer to => [ Pistons, Checking ]
• Piston and cylinder dimensions, refer to => [ Piston and Cylinder Dimensions ] [1][2]Piston, Engine
• Measuring cylinder bore, refer to => [ Measuring Cylinder Bore ]
• Install with piston ring compressor
8 Piston Rings
• Offset gaps by 120°
• Use piston ring pliers for removal and installation
• The "TOP" marking or side with writing faces the piston crown.
• Gap, measuring, refer to => [ Measuring the Piston Ring Gap ]
• Measuring side clearance, refer to => [ Measuring the Ring to Groove Clearance ]
Measuring the Piston Ring Gap
- Push the piston ring squarely from above down to approximately 15 mm from the bottom end of the cylinder.
- Use a piston without a piston ring for sliding in.
Measuring the Ring to Groove Clearance
- Clean the piston ring groove before checking.
Pistons, 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: 0.03 mm.
Nominal dimension, refer to => [ Piston and Cylinder Dimensions ] [1][2]Piston, Engine.
Measuring Cylinder Bore
- Measure in a diagonal sequence at 3 positions transversely - A - and longitudinally - B - using a cylinder gauge (VAS 6078) or inside micrometer set 18-100 mm (US1033/S).
• Maximum deviation from nominal dimension: 0.08 mm.
Nominal dimension, refer to => [ Piston and Cylinder Dimensions ] [1][2]Piston, Engine.
Piston Installed Position
The coating on the piston crown could be destroyed.
• Mark the allocation to the cylinder on the piston crown with paint to install used pistons. Do not mark the piston crown with a punch, notch or similar object.
Installation position:
• The arrows on the piston heads point to the belt pulley side.
• Large valve recesses - 1 - point toward center of engine.
Mark Connecting Rod
• Only replace the connecting rods as a set.
- Mark the connecting rod and connector rod bearing caps to each other and to the cylinder - arrow - with paint for installation.
Connecting Rod Installation Position
• The molded tabs - arrows - on the beveled surfaces of connecting rod pairs "1 and 2", "3 and 4", "5 and 6" and "7 and 8" must face each other.
Oil Spray Jet for Piston Cooling
1. Oil spray jet
2. Insert bolts with locking compound and tighten to 9 Nm; Locking compound, refer to the electronic parts catalog ETKA.
• Do not bend piston spray nozzles.
• Bend piston spray nozzles must be replaced.