Checking The Valve Seats

VALVES AND VALVE SPRINGS

3. Eliminate:                                              EAS24300

                                                           CHECKING THE VALVE SEATS
 • Carbon deposits
                                                           The following procedure applies to all of the
   (from the valve face and valve seat)
                                                           valves and valve seats.
4. Check:
                                                           1. Eliminate:
 • Valve face
                                                            • Carbon deposits
   Pitting/wear → Grind the valve face.
                                                              (from the valve face and valve seat)
 • Valve stem end
                                                           2. Check:
   Mushroom shape or diameter larger than the
                                                            • Valve seat
   body of the valve stem → Replace the valve.
                                                              Pitting/wear → Replace the cylinder head.
5. Measure:
                                                           3. Measure:
 • Valve margin thickness D “a”
                                                            • Valve seat width C “a”
   Out of specification → Replace the valve.
                                                              Out of specification → Replace the cylinder
           Valve margin thickness D (intake)                  head.
            0.80–1.20 mm (0.0315–0.0472 in)
           Valve margin thickness D (ex-                              Valve seat width C (intake)
           haust)                                                      0.90–1.10 mm (0.0354–0.0433 in)
            0.50–0.90 mm (0.0197–0.0354 in)                           Valve seat width C (exhaust)
                                                                       0.90–1.10 mm (0.0354–0.0433 in)

6. Measure:
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 • Valve stem runout                                       a. Apply Mechanic’s blueing dye (Dykem) “b”
   Out of specification → Replace the valve.                  onto the valve face.
NOTE:
• When installing a new valve, always replace
  the valve guide.
• If the valve is removed or replaced, always re-
  place the valve stem seal.

           Valve stem runout
            0.010 mm (0.0004 in)

                                                           b. Install the valve into the cylinder head.
                                                           c. Press the valve through the valve guide and
                                                              onto the valve seat to make a clear impres-
                                                              sion.
                                                           d. Measure the valve seat width.
                                                       NOTE:
                                                           Where the valve seat and valve face contacted
                                                           one another, the blueing will have been re-
                                                           moved.
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