Cooling System - Yamaha DT501988 Owner's Manual

6. After replacement of transmission oil,
be sure to check for oil leaks.
H-509K
Cooling system
The coolant is circulated by an impeller type
pump mounted on the right-hand crankcase
and driven by a gear. The coolant is drawn
by the pump from the bottom tank of the
radiator, through the pipe, and discharged
into the cylinder-head and cylinder head.
The coolant passes from the cylinder through
coolantpassages. After circulating around the
combustion chamber jacket,it enters the ra-
diator upper tank via the pipe. The heated
coolant from the engine then passes down
through the finned tubes to the bottom tank
of the radiator. These finned tubes present a
large surface area to the air and dissipate the
heat.
7-8
1 . If your motorcycle overheats
U-705K
&WARNING:
Do not remove the radiator cap when
the engine and radiator are hot.
Scalding hot fluid and steam may be
blown out under pressure, which could
cause serious injury. When the engine
has cooled, open the radiator cap by
the following procedure: Remove the
radiator cover by removing the screw.
Place a thick rag, like a towel, over the
radiator cap, slowly rotate the cap
counterclockwise to the detent. This
procedure allows any residual pressure
to escape. When the hissing sound has
stopped, press down on the cap while
turning counterclockwise and remove
it.