Volkswagen Workshop Service and Repair Manuals

• Piston ring
• ◆ Offset gaps by 120 °
• ◆ Remove and install with piston ring pliers
• ◆ "TOP" faces towards piston crown
• ◆ Checking ring gap=> Fig. 1
• ◆ Checking ring to groove clearance
  => Fig. 2

• Piston
• ◆ Engine codes 1Z, AHU, AEY, AFN, AVG, ALE with combustion chamber
• ◆ Mark installation position and cylinder number
• ◆ Mark installation position and allocation piston/cylinder for engine codes 1Z, AHU, AEY, AFN, AVG, ALE => Fig. 4
• ◆ Arrow on piston crown points to pulley end
• ◆ Install using piston ring clamp
• ◆ Cracks on piston skirt, renew piston
• ◆ Checking piston projection at TDC
  =>Page 13-53

• Piston pin
• ◆ If difficult to remove, heat piston to 60 °C
• ◆ Remove and install with VW 222a
• ◆ ø = 26 mm for engine codes 1Z, AHU, AAZ, AEY, AFN, AVG, ALE
  ø = 24 mm for engine code 1Y
• Circlip
• Conrod
• ◆ Only renew as a set
• ◆ Mark cylinder number -A-
• ◆ Installation position:
  Marking -B- faces towards pulley end
• ◆ Length:
  Engine codes
  1Z, AHU, AAZ, AEY, AFN, AVG, ALE
  = 144 mm
  1Y = 150 mm

• Bearing shell
• ◆ Note version:
  for engine code AFN, AVG upper bearing shell (faces towards piston) of more durable material
  Identification:
  Black line on running surface in area of joint
• ◆ Note installation position
• ◆ Do not interchange used bearing shells
• ◆ Ensure retaining lugs fit tightly in recesses
• ◆ Axial clearance
  Wear limit: 0.37 mm
• ◆ Check radial clearance with Plastigage:
  Wear limit: 0.08 mm
  Do not rotate crankshaft when checking radial clearance
• ◆ Width:
  Engine codes
  1Z, AHU, AAZ, AEY, AFN, AVG,
  ALE = 20 mm
  1Y = 19 mm

• Cylinder block
• ◆ Checking cylinder bores
  =>Fig. 3
• ◆ Piston and cylinder dimensions
  =>Page 13-55
• Conrod bearing cap
• ◆ Note installation position
• Fitted pin
• ◆ The fitted pin must seat securely in the conrod, not in the bearing cap
• Oil spray jet
• ◆ For piston cooling
• 10 Nm
• ◆ Install with AMV 188 100 02
• Conrod bolt, 30 Nm + 1/4 turn (90 °) further
• ◆ Renew
• ◆ Oil threads and contact surface
• ◆ To measure radial clearance use old bolts

→ Fig. 1     Checking piston ring gap

• ‒ Push ring squarely from above down to approx. 15 mm from bottom end of cylinder.

→ Fig. 2     Checking ring to groove clearance

Clean groove before check.

→ Fig. 3     Checking cylinder bores

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Internal dial gauge 50...100 mm

• ‒ Take measurements at 3 positions in both lateral -A- and longitudinal -B- directions, as illustrated. Deviation from nominal dimension
       max. 0.10 mm

Note:

Measuring the cylinder bores must not be done when the cylinder block is mounted on a repair stand with adapter bracket VW 540, as incorrect measurements would then be possible.

→ Fig.4     Piston installation position and piston/cylinder allocation

Piston in cylinders 1 and 2:

Larger inlet valve chamber towards flywheel -arrows-

Piston in cylinders 3 and 4:

Larger inlet valve chamber towards belt pulley side -arrows-.

Note:

New piston allocation to cylinders is shown by a coloured marking on piston crown.

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