Yanmar 1GM User Manual page 202

196 C HA PTER NINE
~~lI:~:"-
Oil pres sure
::; sender
Waming
lamp
Cootant
temperature
sender
Fu~
K.y
Switch
1
: Bane ry
pressu re sender on 2GM, 2GM2 0. J GM, 3GM30, 3HM
and J HM35 engines is located below the oil filler as
shown in Figul"e 24.
To check the oil pressure sender, proceed as follows:
CAUTION
Before checking the oil pressure sender,
make sure the engine is filled with oil.
I. Discon nect the wire at the sender terminal.
2. Connect an ohmm eter betw een the sender terminal and
the hex on the base of the sender.
3. With the eng ine off the meter sho uld show co ntinuity.
4. Start the eng ine. As the oil pressure builds abo ve 9 .R
kPa (1.4 psi), the meter should swit ch from continui ty to
no continuity. If it docs not, replace the sender unit.
Coola nt Tempera ture Send er
Refer 1 0 the coo lant temperature circuit in Figure 25,
The sender is open at amb ient tem perature, which pre-
vents current from lighting the warni ng lamp and activat-
ing the alarm buzzer. Whcn coo lant rises above the
spec ificat ion. the sender closes, the warni ng lamp and the
alarm buzzer come on.
On IGM and IGM 10 engines, the coo lant temperature
sensor is loca ted on the cylinder head (f igu re 26). The
coo lant temperature senso r on two or three cyl inder en-
gines is located on the front or side ofthe thermostat hous-
ing (Figure 27,typ ical).
Two different senders may be used depending on the
type of coo ling system. Eng ines equipped with seawater
coo ling are equipped with a sender that is color -coded
white and has a closed temperature of 148-154° F (63-67°
C). Engines equipp ed with freshwater coo ling arc
equipped with a sender that is co lor-coded green and has a
closed temperature of 193-202° F (89_95°
C).
To check the coolant sender, proceed as fo llows:
I. Remo ve the sw itch fro m the engine.
2. Co nnect a digital ohmmeter to the switch.
3. Immerse the sending unit and a cooki ng thermometer
in a co ntainer of oil.
4. Heat the container ove r a flamc lcss heat source and
note the ohmmeter reading. The switch shou ld close as
follows:
a. seawater switch (white)-148-154° F (63-67 ° C).
b. freshwater switch (grecn}-- 193-202
Q
F (89-95 ° C).
5. Remove the conta iner from the heat and let it cool. The
switch should reopen as follows:
a. seawa ter switch (whi te}--136° F (58° C).
b. freshwater swi tch (green}-- I90° F (88°
C).
6. Replace the switch if'it does not function as specified
at each temperature range.