Procedures

Valve seats, refacing
Special tools and equipment
^ Depth gauge
^ Valve Seat Refacing Tool

Notes:
^ When servicing engines with leaking valves, refacing or replacing valve seats and valves is not sufficient. It is particularly important to check valve guides for wear on engines with longer running times, Refer to Testing and Inspection.
^ Only reface valve seats enough unto a perfect contact pattern is obtained. Before refacing, determine maximum refacing dimension. If refaced dimension is exceeded, hydraulic valve lifter function is no longer guaranteed and cylinder head must be replaced.

Maximum permitted refacing dimension is calculated as follows:
^ Insert valve and press tightly against valve seat.

Note: If valve is replaced during repair, use new valve for measurement.





^ Measure gap -a- vertically between tip of valve stem end and upper edge of cylinder head -1-.
^ Determine maximum allowable refacing dimension using distance measured and minimum dimension.
Minimum dimensions: Outer intake valves 31.0 mm, center intake valve 32.3 mm, exhaust valve 31.9 mm
Measured distance -a- minus minimum dimension = maximum permissible refaced dimension.

Example:





*) Maximum allowable refacing dimension is represented in illustrations for refacing valve seats as dimension "b".





Refacing intake valve seat
a = 26.2 mm
b = Maximum allowable refacing dimension*
c = 1.5 to 1.8 mm
Z = Lower edge of cylinder head
a = 45° Valve seat angle
p = 30° Upper correction angle
y = 60° Lower correction angle

Refacing exhaust valve seat
a = 29.0 mm
b = Maximum allowable refacing dimension*
c = approximately 1.8 mm
z = Lower edge of cylinder head
a = 45° Valve seat angle
p = 30° Upper correction angle
Y = 60° Lower correction angle
*) How to calculate maximum permissible refacing dimension.