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Home >> Subaru >> 2021 >> Forester Base >> Repair and Diagnosis >> Engine Mechanical >> Mechanical >> Engine Mechanical System >> Cylinder Head >> Inspection >> Valve And Valve Guide

Valve And Valve Guide

WARNING: Metallic sodium is encapsulated in the exhaust valve. Metallic sodium is a strong alkaline material and thus prone to serious chemical reaction. When handling or disposing of the valve, be sure to confirm "DISPOSAL". Ref. to MECHANICAL (H4DO)>Cylinder Head>DISPOSAL .
  1. Check the valve flange and stem for damage, wear or deformation.
  2. Measure the thickness "T" of valve head edge as shown in the figure using a caliper gauge. If it is not within the standard, replace the valve.
    NOTE:
    • It is possible to differentiate between the intake valve and the exhaust valve by their overall length.

      Valve overall length:

      Intake

      104.95 mm (4.1319 in)

      Exhaust

      96.53 mm (3.8004 in)

    • When the valve is replaced, lap the valve. Refer to "VALVE SEAT" for lapping. Ref. to MECHANICAL (H4DO)>Cylinder Head>INSPECTION>VALVE SEAT .

      Valve head edge thickness T:

      Intake (A)

      Standard

      0.8 - 1.2 mm (0.0315 - 0.0472 in)

      Exhaust (B)

      Standard

      1.0 - 1.4 mm (0.0394 - 0.0551 in)

    G13224522Courtesy of SUBARU OF AMERICA, INC.
  3. Check the clearance between valve and valve guide. Check the clearance between valve and valve guide by measuring the outer diameter of valve stem and the inner diameter of valve guide respectively.
    1. Measure the outer diameter of valve stem with a micrometer. If it is not within the standard, replace the valve.
      NOTE:
      • Measurement should be performed at a temperature of 20°C (68°F).
      • Measure the outer diameter of the valve stem at the six locations as shown in the figure, and read the value of most worn location.
      • When the valve is replaced, lap the valve. Refer to "VALVE SEAT" for lapping. Ref. to MECHANICAL (H4DO)>Cylinder Head>INSPECTION>VALVE SEAT .

      Valve stem outer diameter: 

      Intake 

      Standard 

      5.455 - 5.470 mm (0.2148 - 0.2154 in)

      Exhaust 

      Standard 

      5.445 - 5.460 mm (0.2144 - 0.2150 in)

      G08317115Courtesy of SUBARU OF AMERICA, INC.
    2. Using a caliper gauge, measure the inner diameter of valve guide. If it is not within the standard, replace the valve guide. For replacement procedure, refer to step 4.
      NOTE:
      • Measurement should be performed at a temperature of 20°C (68°F).
      • Measure the inner diameter of the valve guide at the six locations as shown in the figure, and read the value of most worn location.

      Valve guide inner diameter: 

      Standard 

      5.500 - 5.512 mm (0.2165 - 0.2170 in)

      G13224524Courtesy of SUBARU OF AMERICA, INC.
    3. Calculate the clearance between valve and valve guide.

      Clearance between valve and valve guide: 

      Intake 

      Standard 

      0.030 - 0.057 mm (0.0012 - 0.0022 in)

      Exhaust 

      Standard 

      0.040 - 0.067 mm (0.0016 - 0.0026 in)

  4. If the clearance between valve and valve guide exceeds the standard, replace the valve or valve guide, whichever shows the greater amount of wear or damage. For replacement procedure of valve guide, refer to the following.
    NOTE: When the valve is replaced, lap the valve. Refer to "VALVE SEAT" for lapping. Ref. to MECHANICAL (H4DO)>Cylinder Head>INSPECTION>VALVE SEAT .
    1. Insert ST into the valve guide with the combustion chamber upward and remove the valve guide using plastic hammer.
      CAUTION:
      • Place a wood board wrapped with a waste cloth to stabilize the cylinder head before work.
      • Use special care not to damage the cylinder head during work.
      • Always strike the ST vertically with a plastic hammer. Otherwise, the ST can be damaged.

      Preparation tool: 

      ST: VALVE GUIDE REMOVER AND INSTALLER (499765700)

      G13224525Courtesy of SUBARU OF AMERICA, INC.
    2. Before installing the valve guide, make sure that neither scratches nor damages exist on the inner surface of valve guide installation holes of cylinder head.
    3. Draw a reference line (A) used for insertion on the valve guide using a marker as shown in the figure.
      NOTE: A reference line for insert is used as a guide when tapping-in the valve guide.

      Valve guide inserting reference line position L: 

      15 mm (0.5906 in)

      G10262758Courtesy of SUBARU OF AMERICA, INC.
    4. Apply a enough coat of engine oil to the valve guide, and set the valve guide on the cylinder head with the combustion chamber downward.
    5. Insert the ST into the valve guide, and tap-in the valve guide to the reference line (A) for insert using plastic hammer.
      CAUTION:
      • During work, place a waste cloth, etc. to avoid scratching the mating surface of the cylinder head.
      • Use special care not to damage the cylinder head during work.
      • Always strike the ST vertically with a plastic hammer. Otherwise, the ST can be damaged.

      Preparation tool: 

      ST: VALVE GUIDE REMOVER AND INSTALLER (499765700)

      G13224527Courtesy of SUBARU OF AMERICA, INC.
    6. Measure the valve guide protrusion amount "Q" as shown in the figure using a caliper gauge. Insert the ST into the valve guide again, and tap-in the valve guide so that it is positioned within standard by referring to the measured value using plastic hammer.
      CAUTION:
      • During work, place a waste cloth, etc. to avoid scratching the mating surface of the cylinder head.
      • Use special care not to damage the cylinder head during work.
      • Always strike the ST vertically with a plastic hammer. Otherwise, the ST can be damaged.
      NOTE: Be careful not to tap-in excessively by repeating the steps of Tapping-in → Measurement → Tapping-in → Measurement... when installing the valve guide.

      Preparation tool: 

      ST: VALVE GUIDE REMOVER AND INSTALLER (499765700)

      Valve guide protrusion amount Q: 

      Standard 

      11.4 - 11.8 mm (0.4488 - 0.4646 in)

      G13224528Courtesy of SUBARU OF AMERICA, INC.
      G13224529Courtesy of SUBARU OF AMERICA, INC.
    7. Ream the inside of valve guide with the combustion chamber upward using the ST. Put the ST in valve guide, and rotate the ST slowly clockwise while pushing it lightly. Bring the ST back while rotating it clockwise.
      CAUTION:
      • Place a wood board wrapped with a waste cloth to stabilize the cylinder head before work.
      • Use special care not to damage the cylinder head during work.
      NOTE:
      • Apply engine oil to the ST.
      • If the inner surface of valve guide is damaged, the edge of ST should be slightly ground with oil stone.
      • If the inner surface of valve guide becomes lustrous and the ST does not chip, use a new ST or remedy the ST.

      Preparation tool: 

      ST: VALVE GUIDE REAMER (499765900)

      G13224530Courtesy of SUBARU OF AMERICA, INC.
    8. After reaming, clean the valve guide to remove chips.
    9. Check the seating width between valve and valve seat. Ref. to MECHANICAL (H4DO)>Cylinder Head>INSPECTION>VALVE SEAT .
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