Pistons And Connecting Rod Overview

Fig 1: Identifying Piston And Connecting Rod, Component Overview

Courtesy of AUDI OF AMERICA, LLC

1. Bolt
   • 30 Nm + 90° (¹ /₄ ) turn.
   • Replace
   • Lubricate the thread and contact surface.
   • use old bolt to measure radial play.
2. Connecting Rod Bearing Cap
   • Mark which cylinder to which it belongs -B-.
   • Installation position: The -A- markings face toward the lower side of the piston crown (to the center of teh cylinder block).
3. Bearing Shells
   • Mark used bearing shells.
   • Bearing shell retaining tabs must be firmly seated in the notches.
   • Installation position: The retaining tabs of both bearing shells lie on the same side of the connecting rod.
   • Axial Play, Measuring, refer to CONNECTING ROD, MEASURING AXIAL CLEARANCE .
   • Radial Play, Measuring, refer to CONNECTING ROD, MEASURING RADIAL CLEARANCE .
   • Replacement parts are color coded "yellow" for lower and "red" for upper.
4. Connecting Rod
   • With oil hole for piston pin lubrication.
   • Always replace as a set.
   • Mark which cylinder to which it belongs -B-.
   • Installation position: The -A- markings face toward the lower side of the piston crown (to the center of teh cylinder block).
5. Locking Ring
6. Piston Pin
   • if tight, heat piston to 60°C.
   • Remove and install with the Pilot DriftVW222A.
7. Piston
   • Checking, refer to Fig 4.
   • Mark installed location to connecting rod and the cylinder to which it belongs.
   • shallow side of piston head faces cylinder block center.
   • Piston and Cylinder Dimensions, refer to PISTON AND CYLINDER DIMENSIONS .
   • Install with the Injector/Combustion Chamber Seal Tool SetT10133, refer to PISTON, INSTALLATION .
8. Piston Rings
   • Compression rings
   • Offset gaps by 120°
   • Use piston ring pliers for Removing and Installing.
   • Mark "TOP" must face toward piston head.
   • Checking the ring gap, refer to Fig 2.
   • Checking the piston ring groove clearance, refer to Fig 3.
9. Piston Ring
   • Oil scraping ring
   • 3-part
   • Install upper steel ring so gap is offset by 120° to neighboring compression ring.
   • Offset all oil scraping ring component gaps to each other.

Fig 2: Checking Piston Ring Gap

Courtesy of AUDI OF AMERICA, LLC

-- Slide piston ring from above into lower cylinder opening as follows, using piston without piston ring.

• Right angle to cylinder wall.
• Until approximately 15 mm from bottom edge of cylinder.

-- Measure with feeler gauge.

Fig 3: Checking Piston Ring Groove Clearance

Courtesy of AUDI OF AMERICA, LLC

-- Clean piston ring groove.

-- Measure with feeler gauge.

Fig 4: Checking Piston Deviation

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-- Measure with external micrometer 75 to 100 mm as follows:

• Approximately 6 mm from bottom edge.
• Offset 90° to piston pin axle.

Deviation from nominal dimension:

• Maximum 0.04 mm.

Nominal dimension, refer to PISTON AND CYLINDER DIMENSIONS .

Fig 5: Checking Cylinder Bore

Courtesy of AUDI OF AMERICA, LLC

-- Measure with internal dial gauge 50 to 100 mm as follows:

• Tighten in a diagonal sequence in 3 places in direction -A- and direction -B-.

Deviation from nominal dimension:

• Maximum 0.08 mm.

Nominal dimension, refer to PISTON AND CYLINDER DIMENSIONS .