Thermal Switch

EXC. MODELS W/ENGINE COOLING FAN IGNITION ADVANCE SYSTEM

1. Connect a suitable ohmmeter onto thermal switch terminals.
2. Place thermal switch into a container filled with oil. Submerge thermal switch in oil up to its flange. Do not completely submerge thermal switch. When an oil bath solution is used to heat the thermal switch, ensure thermal switch does not come in contact with container bottom or its side or thermal switch damage will result.
3. Place a suitable thermometer into the oil bath as close to the thermal switch as possible.
4. Heat the oil bath solution and observe both thermometer and ohmmeter readings.
5. The thermal switch should activate (as indicated by a small deflection by the ohmmeter needle) with oil bath solution heated to approximately 207-216 degrees F.
6. Allow thermal switch to cool from approximately 207 degrees F to 198 degrees F. At approximately 198 degrees F, the thermal switch should deactivate (as indicated by a large deflection on ohmmeter needle).
7. If the thermal switch does not operate as specified in steps 5 and 6, replace thermal switch assembly.

MODELS W/ENGINE COOLING FAN IGNITION ADVANCE SYSTEM

1. With timing light correctly installed and engine idling, connect a jumper wire between thermal switch connector terminals.
2. The engine cooling fan should start to operate and ignition timing advance 5-10 degrees on B-28 or 13 degrees on B-23 and B-230 engines as indicated by the timing.
3. If not, replace thermal switch.