Yanmar 1GM User Manual page 22

GENERAL INFORMATI ON
IS
Compression Gauge
An engine with low compression cannot be properly
tuned and
will
not develop full power. A compression
gauge (Figur e 37) and adapter specifically designed for
diesel applications is required to measure the high cylin-
der compression pressure (390-470psi [2700-3300kPa]).
lf these specialized tools are not available, refer compres-
sion testing to a quali fied technician. Sec Chapter Three.
Multimeter or YOM
This instrument (Figure 38) is required for electrical
system troub leshooting.
Hattery Hydrometer
A hydrome ter (Figure 39) is the used to check a bat-
tery's state of charge. A hydromete r measures the weight
or de nsity ofthe sulfuric acid in the battery's electrolyte in
specific gravity.
Screw Pitch Gauge
A screw pitch gauge (F igure 40) determines the thread
pitch of bolts, screws, studs, etc. The gauge is made up of
a number of thin plates . Each plate has a thread shape cut
on one edge to match one thread pitch. When using a
screw pitch gauge to determine a thread pitch size, fit dif-
ferent blade sizes onto the bolt thread until both threads
match.
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