3512B Engine Caterpillar

Illustration 1	g01285348
Typical air shutoffs on a 3500B engine (1) Air shutoffs

Illustration 2	g01285609
Left hand side air shutoff in the OPEN position

Illustration 3	g01285610
Right hand side air shutoff in the OPEN position

Refer to the Troubleshooting Guide, "Air Shutoff System" information in your Service Manual for further information about the electrical system for the air shutoff system.

Note: Do not start the engine. Ensure that the engine control is in the "OFF" position.

1. Ensure that both air shutoff gates are latched in the OPEN position. Ensure that both air shutoff switches are connected. Turn the power for the engine control panel to the ON position. The air shutoff gates should remain in the OPEN positions. If the air shutoff gates do not remain in the OPEN positions, check the wiring for the air shutoffs. When step 1 has been successfully completed, proceed to step 2.

2. While the power for the engine control panel is in the ON position, activate the "EMERGENCY STOP" switch. Both air shutoff gates should close. If the air shutoff gates do not close, check the wiring for the air shutoffs and the wiring for the solenoids. Both air shutoff gates must close before proceeding to step 3.

3. Turn the power for the engine control panel to the OFF position. Reset the "EMERGENCY STOP" switch to the RUN position. Reset the right side air shutoff to the OPEN position. Turn the power for the engine control panel to the ON position. Select "Run/Start" on the engine control panel. The engine should fail to start. If the engine does not start, proceed to 4. If the engine starts, turn off the engine. Check the right side air shutoff. Check the wiring for the right side air shutoff. Retest the air shutoff. When the procedure in 3 is followed and the engine fails to start, proceed to 4.

4. Reset the "EMERGENCY STOP" switch to the RUN position. Set the power for the engine control panel to the ON position. Activate the"EMERGENCY STOP" switch. Both air shutoff gates should close. Set power for the engine control panel to the OFF position. Reset the "EMERGENCY STOP" switch to the RUN position. Reset the left side air shutoff to the OPEN position. Turn the power for the engine control panel to the ON position. Select "START/RUN" on the engine control panel. The engine should fail to start. If the engine does not start, proceed to 5. If the engine starts, turn off the engine. Check the left side air shutoff. Check the wiring for the left side air shutoff. Retest the left side air shutoff. When the procedure in step 4 is followed and the engine fails to start, proceed to 5.

5. Turn the power for the engine control panel to the ON position. Reset both air shutoffs. Start the engine. Disconnect only the right side air shutoff. Both air shutoff gates should close. The engine should shut down. If the engine does not shut down, use the "EMERGENCY STOP" switch to stop the engine. Check the wiring for both air shutoffs. Use the above procedure in order to retest the right side air shutoff. When the procedure in step 5 is followed and results of the test are successful, reconnect the right side air shutoff. Reset both air shutoffs.

6. Turn the power for the engine control panel to the ON position. Reset both air shutoffs. Start the engine. Disconnect only the left side air shutoff. Both air shutoff gates should close. The engine should shut down. If the engine does not shut down, use the "EMERGENCY STOP" switch to stop the engine. Check the wiring for both air shutoffs. Use the above procedure in order to retest the left side air shutoff. When the procedure in 6 is followed and the results of the test are successful, reconnect the right side air shutoff. Reset both air shutoffs.

7. Testing is complete only when the engine successfully passes steps 1 through 6.

8. Reset both air shutoffs. Ensure that the "EMERGENCY STOP" switch has been reset. Operate the engine normally.