Thermo King UT-1200, Manual

Page: 109 / 169

Engine Maintenance
109
Adjust Engine Valve Clearance
The valve clearance should be checked after every
2000 operating hours, maximum. It is important
that valves be adjusted to the correct
specifications for satisfactory engine operation.
Insufficient valve clearance will result in
compression loss and misfiring of cylinders
resulting in burned valves and seats. Excessive
valve clearance will result in noisy valve
operation and abnormal wear of the valves and
rocker arms. The intake and exhaust valves are
adjusted with the valve in the closed position.
NOTE: The cylinders on these engines are
numbered from the flywheel end to the water
pump end. The number 1 cylinder is next to the
flywheel. The number 2 cylinder is in the middle
and the number 3 cylinder is next to the water
pump. The timing marks on the flywheel are also
numbered this way.
The timing marks on the flywheel of the three
cylinder engines are stamped 120 degrees apart.
The top dead center marks have the cylinder
number stamped next to them. The injection
timing marks have no identification marks (see
Figure 183).
The index timing mark is stamped on the side of
the starter mounting plate that faces the
flywheel. This index timing mark is on the intake
side of the engine.
On the three cylinder engines the order for the
flywheel timing marks is 1, 2, 3, but the firing
order is 1, 3, 2. The reason for this is that the
engine fires every 240 degrees of crankshaft
rotation. Therefore, when adjusting the valves,
check the number 1 cylinder first. Then rotate
the engine past the number 2 cylinder timing
marks to the number 3 cylinder timing marks
and check the number 3 cylinder. Finally, rotate
the engine past the number 1 cylinder timing
marks to the number 2 cylinder timing marks
and check the number 2 cylinder.
Figure 182: Valve Adjustment and Firing Order
1. Remove the cylinder head cover.
2. Place the engine at top dead center of the
compression stroke for the number 1 cylinder.
a. Rotate the engine in the normal direction
of rotation (counterclockwise viewed from
the flywheel end) until the top dead center
timing mark for the number 1 cylinder on
the flywheel lines up with the index timing
mark on the starter mounting plate.
b. Check the rocker arms on the number 1
cylinder to see if they are loose.
CAUTION: Loosen all of the injection
lines at the injection nozzles to prevent the
possibility of the engine firing while it is
being rotated.
1. Top Dead Center Timing Mark for Number 1
Cylinder
2. Index Timing Mark on Starter Mounting Plate
Figure 183: Timing Marks
1
2