Valve & Valve Guide

Valve head edge thickness H: 

Intake (A)

Standard 

0.8-1.2 mm (0.031-0.047 in)

Exhaust (B)

Standard 

1.0-1.4 mm (0.039-0.055 in)

Fig 1: Checking Valve Head Edge Thickness H

Courtesy of SUBARU OF AMERICA, INC.

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)

   Fig 2: Measuring Outer Diameter Of Valve Stem

   Courtesy 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)

   Fig 3: Measuring Inner Diameter Of Valve Guide

   Courtesy 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)

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.

   ST 499765700 VALVE GUIDE REMOVER AND INSTALLER 

   Fig 4: Tapping Valve Guide Using Plastic Hammer

   Courtesy 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) for insert on the valve guide using a marker as shown in the figure.
   NOTE:

   • Use a new valve guide.
   • 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)

   Fig 5: Checking Valve Guide Inserting Reference Line Position

   Courtesy 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.

   ST 499765700 VALVE GUIDE REMOVER AND INSTALLER 

   Fig 6: Tapping Valve Guide Using Plastic Hammer

   Courtesy of SUBARU OF AMERICA, INC.
6. Measure the valve guide protrusion amount "L" as shown in the figure using a caliper gauge. Insert the ST into the valve guide, 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.

   ST 499765700 VALVE GUIDE REMOVER AND INSTALLER 

   Valve guide protrusion amount L:

   Standard 

   11.4-11.8 mm (0.449-0.465 in)

   Fig 7: Checking Valve Guide Protrusion Amount L

   Courtesy of SUBARU OF AMERICA, INC.
   Fig 8: Tapping Valve Guide

   Courtesy 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.

   ST 499765900 VALVE GUIDE REAMER 

   Fig 9: Reaming Valve Guide Using ST

   Courtesy 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 .