Valve Guide

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 three locations as shown in the figure, and read the value of most worn location.
   • If the valve is replaced, put a small amount of grinding compound on the valve seat surface of cylinder head, and lap the valve and valve seat surfaces.

   Valve stem outer diameters: 

   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 1: Measuring Valve Stem Outer Diameter Using Micrometer

   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 2).
   NOTE: Measurement should be performed at a temperature of 20°C (68°F).

   Valve guide inner diameter: 

   Standard 

   5.500 - 5.512 mm (0.2165 - 0.2170 in) 

   Fig 2: Measuring Valve Guide Inner Diameter

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

Clearance between the valve guide and valve stem: 

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.

   ST 499765700 VALVE GUIDE REMOVER AND INSTALLER

   Fig 3: Removing 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 holes in 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 4: Identifying Length Of Valve Guide From Reference Line

   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.

   ST 499765700 VALVE GUIDE REMOVER AND INSTALLER

   Fig 5: Tapping Valve Guide To Reference Line 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 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.
   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 6: Measuring Valve Guide Protrusion Length

   Courtesy of SUBARU OF AMERICA, INC.
   Fig 7: Pressing To Fitting Valve Guide To Position

   Courtesy of SUBARU OF AMERICA, INC.
7. Ream the inside of valve guide with the combustion chamber upward using 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 when reaming.
   • 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 8: Reaming Inside Of Valve Guide With Combustion Chamber Using Valve Guide Reamer

   Courtesy of SUBARU OF AMERICA, INC.
8. After reaming, clean the valve guide to remove chips.
9. Recheck the contact condition between valve and valve seat after replacing the valve guide.