WHEN REMOVING THE CAP, LOOSEN IT SLOWLY AND THEN PAUSE A MOMENT. THIS WILL
AVOID POSSIBLE BURNING BY HOT WATER OR STEAM. CONTINUE TO TURN THE CAP TO
THE LEFT UNTIL YOU CAN REMOVE IT.
3. Tubes. Because these are very small they can become easily clogged, or partially so, by rust and scale. The general
condition of the Cooling System Components and operating temperature are indications as to whether or not tubes
are clean. Another good test is to feel core for cold spots.
4. Fins. These thin metal sheets radiate or pass off heat picked up by tubes. They should be kept free of foreign matter,
so as to allow the free passage of air. Bent fins should be straightened.
Engine Water Jacket.
The water jacket permits coolant to be circulated around the cylinder walls, combustion chamber, and valve assemblies.
Some of these coolant passages are small and can easily become clogged if Cooling System does not receive the proper
1. Core Plugs.'rhese are some times mistakenly called freeze plugs. They do not provide protection against freezing
expansion but are only present because of engine block casting methods. Remove and replace core plugs that show
signs of leaking or rusting through. Use installing tool for core plug replacement.
2. Drain Plugs. The water jacket of each engine has one or more drain plugs. These should receive seasonal care and
kept free of rust and scale.
3. Gaskets. Must be in good condition to prevent both internal and external leaks. If there are external leaks around
gaskets, there may also be internal leaks. Proper tightening of the head bolts with a torque wrench is essential for
preventing leaks around head gaskets.
The water pump which circulates coolant through the Cooling System is likewise a most essential part. The pump should
be checked carefully for leaks and proper lubrication, and if leaking, cracked or in bad condition, it should be rebuilt or
Fan and Belts.
The fan should be checked for loose or bent blades. A loose blade might work free during operation and cause damage.
A bent blade will reduce the fans efficiency.
Fan belts must be adjusted for proper tension. A belt adjustment that is just tight enough to prevent slipping on pulleys
may be considered a proper adjustment. A tight belt adjustment is to be avoided since this will damage generator
bearings. When one belt of dual drives is damaged or worn, they must both be changed \fs20 x as a matched pair.
Thermostats used in these trucks are of the nonadjustable type and are incorporated in the Cooling System for the
purpose of retarding or restricting the