Audi Workshop Service and Repair Manuals

Note:

Oil spray jet and pressure relief valve

=> Fig.13-116

• Piston rings
• ◆ Offset gaps by 120°
• ◆ Remove and install with piston ring pliers.
• ◆ Marking "TOP" or inscription must face piston crown.
• ◆ Checking ring gap
  => Fig.13-113
• ◆ Checking ring to groove play
  => Fig.13-113

• Piston
• ◆ Mark installation position and cylinder number.
• ◆ Installation position and arrangement of piston/cylinder
  => Fig.13-114
• ◆ If cracking is visible on piston skirt, replace piston
• ◆ Arrow on piston crown points to pulley end.
• ◆ Install using piston ring clamp.
• ◆ Checking piston projection at TDC =>Page 13-117
• ◆ Piston and cylinder dimensions
  =>Page 13-119
• ◆ Checking => Fig.13-115

• Piston pin
• ◆ If difficult to remove, heat piston to approx. 60°C.
• ◆ Remove and install with VW 222a
• Circlip
• Conrod
• ◆ Only renew as a set
• ◆ Mark cylinder number B
• ◆ Installation position:
  Markings A face towards pulley side

• Bearing shell
• ◆ Installation position
  => Fig.13-116
• ◆ Do not interchange used bearing shells (mark).
• ◆ Note versions:
  upper bearing shell (facing piston) made of more wear-resistant material
  Characteristic with new bearing shells:
  black line on running surface near cutting point
• ◆ Install bearing shells centrally
• ◆ Ensure tight fit
• ◆ Axial play:
  Wear limit: 0.37 mm
• ◆ Check radial play with Plastigage:
  Wear limit: 0.08 mm
  Do not rotate crankshaft when checking radial play

• Cylinder block
• ◆ Checking cylinder bore
  => Fig.13-115
• ◆ Piston and cylinder dimensions
  =>Page 13-119
• Conrod bearing cap
• ◆ Mark cylinder number B
• ◆ Installation position:
  Markings A face towards pulley side
• Conrod bolt - 30 Nm + 90° (1/4 turn) further
• ◆ Replacing
• ◆ Oil threads and contact surface
• ◆ To measure radial play tighten to 30 Nm but not further

→ Fig. 1    Checking piston ring gap

• ‒ Push ring into cylinder seated squarely on cylinder wall from top down up to approx. 15 mm before bottom edge of cylinder. Use a piston without rings.

→ Fig. 2    Checking ring to groove play

• ‒ Clean groove before checking play.

→ Fig.3    Piston installation position and arrangement of piston/cylinder

• ‒ Mark installation position and allocation on inside of piston (not on piston crown) with electric pen or felt-tip pen.

Pistons in cylinder 1 and 2:

Large valve pocket for inlet valve towards flywheel side -arrows-

Pistons in cylinder 3 and 4:

Large valve pocket for inlet valve towards pulley side -arrows-

Note:

On new pistons the cylinder numbers are marked in colour on the piston crowns.

• ◆ Pistons for cylinder 1 and 2:
  are marked 1/2
• ◆ Pistons for cylinder 3 and 4:
  are marked 3/4

→ Fig. 4    Checking piston

• ‒ Measure approx. 10 mm from the lower edge, offset by 90° to the piston pin axis.
• ‒ Permissible deviation from nominal dimension:
  no more than 0.04 mm.

→ Fig. 5    Checking cylinder bores

Special tools and workshop equipment required

• ◆ Use internal dial gauge 50...100 mm.

• ‒ Take measurements at 3 positions in both lateral direction -A- and longitudinal direction -B-.
• ‒ Permissible deviation from nominal dimension:
  no more than 0.10 mm.

→ Fig.6    Installation position of bearing shell

• ‒ Install bearing shells centrally into conrod or into conrod bearing cap.
• ‒ Dimension a = 2.5 mm

→ Fig.7    Oil spray jet and pressure relief valve

•     1 -    Oil spray jet (for cooling of piston)
•     2 -    Bolt with pressure relief valve - 27 Nm
• ‒ Opening pressure 1.3 ... 1.6 bar