Engine Maintenance (Rev. 04/03)
51
Individual Cylinder Timing and Firing Order
ADJUST ENGINE VALVE CLEARANCE
1. Remove the valve cover. Torque 18 mm diameter head
bolts prior to adjusting the valves: 26.8 ft-lb (36.3
N•m). Valve clearance should be checked after every
2000 operating hours, maximum. It is very important
that valves be adjusted to the correct specifications for
satisfactory engine operation. Insufficient valve clear-
ance will result in compression loss and misfiring of
cylinders resulting in burned valves and seats. Exces-
sive 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.
2. The intake valve and exhaust valve are adjusted to .0079
in. (0.20 mm) with the temperature at 70 F (21 C).
Turn the engine by using the belt on the crankshaft pul-
ley. Rotate the engine in the direction of rotation
(clockwise as viewed next to the flywheel) from the
water pump end.
CAUTION: Make sure the fuel rack is off to prevent
the engine from starting.
a. Turn the engine so number 1 cylinder is on com-
pression with piston to TDC. Both push rods
should turn freely. Adjust both valves on number 1
cylinder.
b. Revolve the crankshaft 240° to TDC mark on num-
ber 3 cylinder, and adjust both valves.
c. Turn the crankshaft 240° to align TDC mark of
number 2 cylinder, and adjust both valves.
d. BE SURE to tighten locking nut while holding the
ball head screw in position.
3. Install the valve cover making sure that the gasket in
position.
FUEL LIMIT SCREW
The fuel limit screw is not adjustable. It is equipped with an
anti-tamper cap to fulfill requirements for CARB (Califor-
nia Air Resources Board) emission regulations. Service
technicians must be CARB certified to perform service on
fuel limit screw for equipment operating in California. All
other equipment can be serviced per recent service bulletins
with special tools and procedures. California service techni-
cians should see your local Thermo King dealer for recent
bulletins.
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