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Cylinder Block: Assembly: Piston

G16524151Courtesy of SUBARU OF AMERICA, INC.
(1) Top ring
(2) Second ring
(3) Oil ring
(4) Piston
(5) Circlip
  1. Install a new circlip on only one side of the piston using long-nose pliers.
    CAUTION:
    • When installing the circlip using long-nose pliers, do not allow the circlip claw sections to contact with each other as shown in the figure.
      G16524128Courtesy of SUBARU OF AMERICA, INC.
      (a) Gap between the circlip claw sections: 1 mm (0.0394 in) or more
    • After operation, make sure the circlip is firmly installed on the circlip groove of the piston.
    • If the circlip needs to be reinstalled after installed to the piston, the circlip cannot be reused. Use a new circlip.
    NOTE: The circlip installation position is determined depending on the position of cylinder to be used. Be careful not to mistake the position.
    G16524153Courtesy of SUBARU OF AMERICA, INC.
    (a) Piston of #1cylinder
    (b) Piston of #3 cylinder
    (c) Piston of #2 cylinder
    (d) Piston of #4 cylinder
    (e) Front mark
    (f) Circlip installation position
  2. Install the oil rings to the piston in the order of expander, lower rail and upper rail by hand.
    NOTE: Oil ring consists of the upper rail, expander and lower rail.
    G16524154Courtesy of SUBARU OF AMERICA, INC.
    (a) Upper rail
    (b) Expander
    (c) Lower rail
    1. Set the ring gap of the expander to the position (A).
      G16524155Courtesy of SUBARU OF AMERICA, INC.
    2. Set the ring gap of the lower rail at position (B), located 60° counterclockwise from the position (A) in the figure.
      G16524156Courtesy of SUBARU OF AMERICA, INC.
    3. Set the ring gap of the upper rail at position (C), located 120° counterclockwise from the position (B) in the figure, and align the upper rail spin stopper (E) to the side hole (D) on the piston.
      • RH side
        G16524157Courtesy of SUBARU OF AMERICA, INC.
      • LH side
    G16524158Courtesy of SUBARU OF AMERICA, INC.
  3. Install the compression rings to the piston in the order of second ring and top ring, using piston ring expander.
    1. Set the ring gap of the second ring to the position (A) in the figure.
      NOTE: The ring mark (2BZ) on the second ring should face the piston crown.
      G16524159Courtesy of SUBARU OF AMERICA, INC.
    2. Set the ring gap of top ring at (B) in the figure on the 180° opposite direction of (A).
      NOTE: The ring mark (1BZ) of the top ring should face the piston crown.
    G16524160Courtesy of SUBARU OF AMERICA, INC.
  4. Check again that the piston rings are installed correctly.
    NOTE: Also check that the ring gaps is not positioned within the range of piston skirt extended line.
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