POWERHEAD
4-11
3-/ 4-Cylinder
OVERHEAT SENSOR
Overheat sensor
(1)
is a heat sensitive switch installed in the
cylinder head to monitor engine temperature The sensor is
connected in series with the warning horn. If the sensor detects
temperature in excess of a predetermined limit, contacts close and
cause the warning horn to emit a continuous tone when the key
switch is ON and the remote control lever is in the FORWARD or
REVERSE position. Depending on model, the engine RPM
limitation function will also activate.
NOTE
The overheat sensor is not standard equipment on
model 40 prior to 1994 but is available as an option.
Function Test
1. Disconnect the overheat sensor bullet connector at the electrical
box and the ground wire.
2. Remove the overheat sensor from the cylinder head.
3. Using a continuity light or calibrated ohmmeter, connect one
tester lead to each sensor lead.
4. Place sensor and thermometer in a heat-resistant container
filled with automotive crankcase oil. Slowly heat the oil using
an external heat source.
WARNING
Avoid fire or explosion:
• Use a heat-resistant container such as Pyrex
®
glassware.
• Use oil with a flashpoint above 300˚F [150˚C].
• DO NOT use open flame as a heat source.
5. Verify the sensor switch reacts to the changing temperature as
follows:
NOTE
Apply light coat of dielectric lubricant to sensor before
installation.
Model
Switch Closed
(Continuity Present)
˚F [˚C]
Switch Open
(No Continuity)
˚F [˚C]
40 / 50 212 [100] 185 [85]
60 / 70 257 [125] 230 [110]
80 / 90 176 [80] 156 [69]
115 / 120 / 140 212 [100] 185 [85]
1
2
3
T1164
T1165
T1248
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