Piston And Connecting Rod Overview

Fig 1: Identifying Assembly Overview: Pistons And Connecting Rod

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

1. Bolt 
   • 45 Nm + 90° (1/4) additional turn.
   • Always replace.
   • Use the old bolts to measure the radial play.
   • Do not turn the additional 90° (1/4) turn when measuring the radial play.
   • Lubricate the threads and contact surface.
2. Connecting Rod Bearing Cap 
   • Pay attention to the installed position.
   • Mark the affiliation to the cylinder -A-.
   • Installed position: The marks -B- point to the belt pulley side.
   • Due to the way the separated connecting rod breaks (cracks), the cap fits only in one position and only onto the respective connecting rod.
   • Separating a new connecting rod. Refer to NEW CONNECTING ROD SEPARATING .
3. Bearing Shells 
   • Note the installed position, refer to Fig 6.
   • Do not interchange used bearing shells (mark them).
   • Axial play:

     New: 0.10 to 0.35 mm

     Wear limit: 0.4 mm

   • Measure radial clearance using Plastigage.

     New: 0.020 to 0.060 mm

     Wear limit: 0.090 mm

     Do not rotate the crankshaft when measuring the radial play.

4. Pressure Relief Valve 

   27 Nm

   • Opening pressure 1.6 to 1.9 bar.
5. Oil Spray Jet 
   • For piston cooling.
   • See notes in OIL PAN AND OIL PUMP .
6. Circlip 
7. Piston Pin 
   • If difficult to move, heat the piston to approximately 60 °C (140 °F).
   • Remove and install using the pilot drift VW 222 A.
8. Piston 
   • Mark the installed position and cylinder allocation.
   • The arrow on the piston face points toward the belt pulley side.
   • Install using a piston ring compressor.
   • Checking, refer to Fig 4.
   • Checking the cylinder bore, refer to Fig 5.
   • For the correct piston and cylinder dimensions, refer to PISTON AND CYLINDER DIMENSIONS .
9. Compression Ring 
   • Offset gaps by 120°
   • Use piston ring pliers for removal and installation.
   • The "TOP" mark must face up toward the piston crown.
   • Checking the ring gap, refer to Fig 2.
   • Checking the piston ring groove clearance, refer to Fig 3.
10. Oil Scraping Ring 
    • 2 pieces.
    • Install the upper steel ring so the gap is offset by 120° to the neighboring compression ring.
    • Offset all oil scraping ring component gaps to each other.
    • Checking the ring gap, refer to Fig 2.
    • The side clearance cannot be measured.
11. Connecting Rod 
    • Only replace as a set.
    • Mark the affiliation to the cylinder -A-.
    • Installed position: The marks -B- point to the belt pulley side.
    • Separating a new connecting rod, refer to NEW CONNECTING ROD SEPARATING .

Fig 2: Identifying Check Of Piston Ring Gap

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required 

• Feeler Gauge

Test Sequence: 

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

Fig 3: Identifying Check Of Piston Ring Gap

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Special tools and workshop equipment required 

• Feeler Gauge

Test Sequence: 

-- Clean the ring groove in the piston before checking.

Fig 4: Identifying Check Of Piston

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Special tools and workshop equipment required 

• Micrometer 75-100 mm VAS 6071

Test Sequence: 

-- Measure the piston approximately 10 mm from the bottom edge and at points offset 90° to the piston pin axis.

• Deviation from nominal dimension: Max. 0.04 mm.

Fig 5: Identifying Check Of Cylinder Bores

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Special tools and workshop equipment required 

• Cylinder Gauge VAS 6078

Test Sequence: 

-- Measure diagonally at 3 positions transversely -A- and longitudinally -B-.

• Deviations from nominal dimension: Max. 0.08 mm

Fig 6: Identifying Installed Position Of Bearing Shell

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Place the bearing shells centrally into the connecting rod and connecting rod cap.

• Dimension -a- must be the same on the left and right sides.