Measuring And Adjusting Valve Clearance - Yanmar 4TNV98 Service Manual

Measuring and Adjusting Valve
Clearance
Measure and adjust while the engine is cold.
• The No. 1 piston position is on the flywheel end
of the engine, opposite the radiator. The firing
order is 1-3-4-2 for 4-cylinder engines.
• 4-cylinder engines fire every 180° of crankshaft
rotation.
• Valve clearance of both the intake and exhaust
valves can be checked with the piston for that
cylinder at top dead center (TDC) of the
compression stroke. When a piston is at TDC of
the compression stroke, both rocker arms will be
loose and the cylinder TDC mark on the flywheel
will be visible in the timing port of the flywheel
housing.
4-Cylinder Engines
Cylinder No.
Valve
No. 1 Cylinder at
TDC Compression
No. 4 Cylinder at
TDC Compression
4TNV98 & 4TNE98 Diesel Engine
NOTES
1
Intake Exhaust
• •
• If there is no valve clearance, and the cylinder is
at TDC of the compression stroke, extreme wear,
or damage to the cylinder head or valves may be
possible.
• If adjusting each cylinder individually, the
cylinder to be adjusted first does not have to be
the No. 1 cylinder. Select and adjust the cylinder
where the piston is nearest to the top dead
center after turning. Make adjustment for the
remaining cylinders in the order of firing by
turning the crankshaft each time.
• To decrease the number of rotations required to
check all cylinders, other cylinders can also be
checked as indicated in the chart below.
2
Intake Exhaust Intake
•
•
104
3
Exhaust Intake
•
• •
Section 3. Engine
4
Exhaust
•