Yanmar 4LHA-HTP User Manual

Chapter 2 Basic Engine
4. Cylinder Head
i4LHA Series
4-2 Valve seat correction procedure
The most common method for correcting unevenness of
the seat surface with a seat grinder is as foflows :
(1) Use a seat grinder to make the surface even.
First use a TO" (for STE/DTE/STP/DTP exhaust and
HTE/HTP intake), 80'(for STE/STP/DTE/DTP intake
and HTE/HTP exhaust) grinder, then grind the seat to the
standard dimension (45*for exhaust), (30°for intake)
using the seat grinder with 15'chanfer.
NOTE : Clean the valve and cylinder head with diesel fuel
oil after valve seat finishing is completed, and make
sure that there are no grindings remaining.
at grinder
Lapping tool
Seat grinder
(standard angle)
Intake valve
Exhaust valve
30'
45"
NOTE : When seat adjustment is necessary, be sure to
check the valve and valve guide. If the clearance
exceeds the tolerance, replace the valve or the valve
guide, and then grind the seat.
NOTE: 1. Insert adjusting shims between the valve spring
and cylinder head when seats have been re-
finished with a seat grinder.
2. Measure valve distortion after valve seat re-
finishing has been completed, and replace the
valve and valve seat if it exceeds the tolerance.
4-3 Intake/exchaust valves, valve guides
4-3.1 Wearing and corrosion of valve stem
Replace the valve if the valve stem is excessively worn or
corroded.
Seat width
K L
r
40 mm
(1.57)
60 mm
(2.36)
ffl-
Seat width
Exhaust valve seat
Intake valve seat
(2) Knead oil into the valve compound and finish the
valve seat using a lapping tool.
(3) Final finishing should
be done with oil only.
Lapping tool
Use a rubber cap type lapping
tool for valves without
a lapping tool groove slit.
mm (in.)
Valve stem
outside dia.
Standard
Wear limit
Intake
8.96 - 8.975
(0.3528 - 0.3533)
8.9 (0.3504)
Exhaust
8.94 - 8.955
(0 352 - 0.3526)
8.9 (0.3504)
2-16

Yanmar 4LHA-HTP Specifications

General

Brand	Yanmar
Model	4LHA-HTP
Category	Engine
Language	English