Pistons And Connecting Rod Overview

Fig 1: Identifying Piston And Connecting Rod, Assembly Overview

Courtesy of AUDI OF AMERICA, LLC

1. Connecting Rod Bolt
   • Replace
   • 30 Nm plus an additional 90° (¹ /₄ turn)
   • Lubricate threads and contact surface
   • Use old bolt to measure radial play
   • Tighten to 30 Nm to measure radial play, do not turn further
2. Pressure Relief Valve

   27 Nm

   • Opening pressure 1.6 to 1.9 bar
3. Oil Spray Jet
   • For piston cooling
4. 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.
   • Affiliation to the cylinder mark -B-
   • Installation position: Markings -A- point to belt pulley side
5. Bearing Shells
   • Upper bearing shell with oil hole for piston pin lubrication
   • Installed location, refer to Fig 6
   • Do not interchange used bearing shells (mark)
   • Axial play new: 0.10 to 0.35 mm Wear limit: 0.40 mm
   • Measure radial clearance with Plastigage: New: 0.02 to 0.06 mm; Wear limit: 0.09 mm. Do not turn crankshaft when checking radial clearance
6. Connecting Rod
   • Only replace as set
   • Affiliation to the cylinder mark -B-
   • Installation position: Markings -A- point to belt pulley side
   • With oil hole for piston pin lubrication
7. Circlip
8. Piston Pin
   • If difficult to move, heat piston to approximately 60 °C (140 °F)
   • Use pilot drift VW 222 A for removal and installation
9. Piston
   • Checking, refer to Fig 4
   • Mark installed position and cylinder allocation
   • Arrow on piston face points toward belt pulley side
   • Install with piston ring compressor
   • For the correct piston and cylinder dimensions, refer to PISTON AND CYLINDER DIMENSIONS 
   • Cylinder bore, checking, refer to Fig 5
10. Piston Rings
    • Offset gaps by 120°
    • Use piston ring pliers for removing and installing
    • "TOP" mark must face up toward piston crown
    • Checking ring gap, refer to Fig 2
    • Check piston ring groove clearance, refer to Fig 3

Fig 2: Checking Piston Ring Gap

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

Fig 3: Checking Piston Ring Gap

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-- Clean the ring groove of piston before checking.

Fig 4: Checking Piston

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

• Deviation from nominal size: max. 0.04 mm.

Fig 5: Checking Cylinder Bores

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Special tools and workshop equipment required 

• Internal dial gauge 50 to 100 mm.
• Inside Micrometer Set 18-100 mm US1033/S

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

• Deviation from nominal size: max. 0.08 mm.

Fig 6: Bearing Shells - Installed Positions

Courtesy of AUDI OF AMERICA, LLC

Bearing shell -1- with connecting rod oil bore -arrow-.

Bearing shell -2- without connected rod cover oil bore.

-- Place bearing shells centrally into connecting rod and connecting rod cover.

Dimension -a- must be the same at left and right.