MerCruiser 305 CID (5.0L) Service Manual page 362

SERVICE MANUAL NUMBER 24
4. Heat sand and observe thermometer and ohmmeter.
5. As temperature rises, switch will close and ohmmeter will indicate continuity. Refer to
chart below for specifications.
48952 Switch
87-86080 Switch
Opens
Closes
6. Turn heat source off. Allow sand to cool. Note readings again to ensure switch or sensor
operates at specified temperature.
7. Replace switch if switch fails within the specified temperature.
Index
90-861327--1 OCTOBER 1999
a - Suitable Container
b - Thermometer
c - Heat Source
d - Switch or sensor
e - Ohmmeter Leads
Engine Coolant Temperature (ECT) Sensor
Temperature - to - Resistance Values
°F
210
160
100
70
40
20
0
-40
e
a
d
c
Coolant Temperature Switch
Opens
150-170°F (66-77°C)
175-195°F (79-91°C)
(Approximate)
°C
100
70
38
20
4
-7
-18
-40
87-88031 Switch
180-200°F (82-93°C)
220-240°F (104-116°C)
INSTRUMENTATION
b
Closes
190-200°F (88-93°C)
215-225°F (102-107°C)
OHMS
185
450
1,800
3,400
7,500
13,500
25,000
100,700
72772
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