Nissan Micra K11 silhouetteK11

CYLINDER HEAD — Inspection (Cont'd) — Valve Guide & Valve Seats (Supplement-V)

EM-5022prose procedure
Continued from EM-5021

Inspection (Cont'd)

Valve guide clearance

  1. 1
    Measure valve stem diameter and valve guide inner diameter as illustrated.
    Standard clearance: 0.025 - 0.052 mm (0.0010 - 0.0020 in)
    Top: micrometer measuring a valve stem (callout 'Micrometer') and bore gauge measuring the valve-guide inner diameter. Bottom: small key showing measurement positions on the guide (Top / Center / Bottom) on an X/Y axis cross-section.
    SEM244D

Valve guide replacement

  1. 1
    Heat cylinder head in oil to 150 to 160°C (302 to 320°F).
  2. 2
    Drive out valve guide using a press or hammer and a suitable tool.
    Cylinder head in oil bath at 150–160°C with hand using a press/hammer driver to drive out a valve guide downwards — illustrates valve-guide replacement step 2.
    SEM871
  3. 3
    Ream cylinder head valve guide bore.
    Reaming bore (service part): 13.495 - 13.527 mm (0.5313 - 0.5326 in)
    Cylinder head on bench with hand using a T-handle reamer to ream the valve-guide bore in the head — illustrates valve-guide replacement step 3.
    SEM245D
  4. 4
    Heat cylinder head to 150 to 160°C (302 to 320°F) and press service valve guide onto cylinder head.
    Installed guide projection — INTAKE: 39 mm; EXHAUST: 35 mm (per figure NEM276)
    Cross-section detail of an installed valve guide protruding into the port; dimension callouts read 'INTAKE 39 mm' and 'EXHAUST 35 mm' from the upper datum to the bottom of the installed guide.
    NEM276

VALVE SEATS

Valve seats inspection

  1. 1
    Check valve and valve seat for contact. Coat the valve face with prussian red lead. If contact is wrong, correct valve seat. If the valve red lead appears 360° around face, the valve stem and face are concentric. If not, repair or replace valve.
    Three valve-seat contact patterns: leftmost 'OK' showing a centered annular contact band, middle 'NG' showing contact band high on the seat, right 'NG' showing contact band low on the seat.
    SEM722BA
  2. 2
    Check valve seats for pitting at contact surface. Resurface or replace if excessively worn. Correct valve seat surface.
    When repairing valve seat, check valve and valve guide for wear beforehand. If worn, replace them. Then correct valve seat.
Valve stem to valve guide standard clearanceTop / Center / Bottom measurement positions
0.025 - 0.052 (0.0010 - 0.0020)mm (in)
Reaming bore (service part)After driving out old guide
13.495 - 13.527 (0.5313 - 0.5326)mm (in)
Cylinder-head heating range for guide R&ROil bath
150 - 160 (302 - 320)°C (°F)
Installed valve guide projection — IntakePer figure NEM276
39mm
Installed valve guide projection — ExhaustPer figure NEM276
35mm
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