ENGINE
6-40
TNV Tier 4 Service Manual
Measuring and Adjusting Valve Clearance
MEASURING AND ADJUSTING
VALVE CLEARANCE
Measure and adjust while the engine is cold.
Note:
• The No. 1 piston position is on the flywheel end of
the engine, opposite the radiator. The firing order
is 1-3-2 for 3-cylinder engines and 1-3-4-2 for 4-
cylinder engines.
• 3-cylinder engines fire every 240° of crankshaft
rotation.
• 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.
• 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.
Example: On a 3-cylinder engine, with the No. 1
piston at TDC on the compression stroke (both
valves closed), the valves indicated on the top line
of the chart can be adjusted without rotating the
crankshaft. To adjust the remaining two valves,
rotate the crankshaft until the No. 1 piston is at
TDC on the exhaust stroke (exhaust valve only
open).
■ 3-cylinder engines
■ 4-cylinder engines
Cylinder No. 1 2 3
Valve Intake Exhaust Intake Exhaust Intake Exhaust
No. 1 cylinder at TDC compression ●●● ●
No. 1 cylinder at TDC exhaust ●●
Cylinder No. 1 2 3 4
Valve Intake Exhaust Intake Exhaust Intake Exhaust Intake Exhaust
No. 1 cylinder at TDC compression ●●● ●
No. 4 cylinder at TDC compression ●● ●●
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