Caterpillar 3500 Series Generator Set

⚠ Hot engine components can cause burns.

⚠ Only qualified service personnel should perform this maintenance.

1. Ensure the engine cannot be started; do not use the starting motor to turn the flywheel.
2. Ensure the engine is stopped and allow valves to cool.
3. Refer to the Systems Operation/Testing and Adjusting Manual for the complete procedure.
4. Set inlet valve lash to 0.38 mm (0.0150 inch).
5. Set exhaust valve lash to 0.76 mm (0.030 inch).
6. Perform initial adjustment at the first scheduled oil change.

Tools: 6V-7070 Digital Multimeter, 9U-7330 Multimeter, 146-4080 Digital Multimeter (RS-232), 7X-1710 Multimeter Probe Group

1. Remove the cover from the exciter.
2. Remove the nut securing the rectifier to the heat sink.
3. Remove the diode lead and lift the rectifier from the heat sink.
4. Connect ohmmeter leads across the rectifier and note reading.
5. Reverse the ohmmeter leads and note reading.
6. Low resistance one direction and high the other indicates a good rectifier.
7. Low resistance both directions indicates shorted rectifier.
8. High resistance both directions indicates open rectifier; replace faulty rectifiers.

⚠ Batteries give off combustible gases which can explode.

⚠ Removing cables with cover in place may cause battery explosion.

1. Turn key start switch to OFF; remove key and all electrical loads.
2. Turn OFF and disconnect battery charger.
3. Disconnect NEGATIVE - cable from NEGATIVE - battery terminal.
4. Disconnect POSITIVE + cable from POSITIVE + battery terminal.
5. Remove the used battery.
6. Install the new battery.
7. Connect cable from starting motor to POSITIVE + terminal.
8. Connect cable from ground plane to NEGATIVE - terminal.

⚠ Never move the battery disconnect switch to OFF while the engine is operating.

1. With switch ON verify electrical components, hour meter and cranking function.
2. Turn the battery disconnect switch to the OFF position.
3. Verify electrical components, hour meter and cranking do not function.
4. Consult your Caterpillar dealer if any item continues to function.

⚠ Pressurized system: hot coolant can cause serious burns.

Tools: 9S-8140 Pressurizing Pump

1. Stop engine and allow to cool; loosen filler cap slowly and remove.
2. Open drain valve or remove drain plug; allow coolant to drain.
3. Flush cooling system with clean water.
4. Close drain valve; clean and install drain plugs per SENR3130 torques.
5. Fill with clean water and cleaner; run at low idle minimum 30 minutes at 82 C.
6. Drain and flush until all cleaning agent is gone.
7. Fill with coolant/antifreeze; do not install filler cap.
8. Run engine at high idle 1 minute to purge air; check level and cap.

⚠ Hot oil and hot components can cause personal injury.

Tools: 1U-8760 Chain Wrench, 175-7546 Oil Filter Cutter Gp

1. Drain crankcase with engine stopped and oil warm.
2. If no drain valve, remove oil drain plug; clean and install plugs.
3. Remove oil filter with 1U-8760 Chain Wrench.
4. Cut filter open with 175-7546 Oil Filter Cutter Gp and inspect for debris.
5. Clean sealing surface of filter mounting base.
6. Apply clean engine oil to new oil filter gasket.
7. Install oil filter; tighten by hand per filter instructions.
8. Fill crankcase; run at low idle 2 minutes and check level.

⚠ Personal injury or death can result from a fire; clean up spilled fuel.

1. Unlock priming pump; operate until resistance is felt.
2. Push in plunger and hand tighten.
3. Crank the engine.
4. If equipped, open vent valve on fuel injection pump housing.
5. Operate priming pump until fuel flow is continuous and free of air.
6. Close vent valve; push in and hand tighten plunger.
7. If no priming pump, crank engine until fuel flows freely.
8. Loosen fuel line nuts at valve cover base one at a time; prime until air-free; retighten.

⚠ Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire.

1. Stop the engine and turn start switch to OFF.
2. Shut off fuel tank supply valve.
3. If equipped, open drain valve and drain fuel from filter case.
4. Remove the fuel filter bowl and wash with clean diesel fuel.
5. Remove the fuel filter.
6. Clean gasket sealing surface of the filter base.
7. Apply clean diesel fuel to the new filter gasket.
8. Install new filter; spin until gasket contacts base and tighten 3/4 turn by hand; install bowl.

⚠ Personal injury or death can result from improper troubleshooting and repair procedures.

Tools: 225-8266 Ammeter Tool Gp, Rheostat, External Power Source

1. Make an external power source.
2. Disconnect F1+ and F2- from voltage regulator; disconnect generator load.
3. Connect rheostat at maximum resistance and external power source to F1+ and F2-.
4. Start generator set and run at IDLE speed.
5. Monitor phase current; gradually increase RPM until rated phase current or full speed.
6. Slowly turn rheostat until rated phase current is reached.
7. On an hourly basis stop and check insulation resistance.
8. Repeat until insulation resistance is acceptable.

⚠ High voltage can cause electrical shocks.

Tools: Audio/visual proximity tester

1. Stop the engine.
2. Attach DO NOT OPERATE tag to engine starting circuit; disconnect starting circuit.
3. Disconnect the generator from the distribution system.
4. Lock out the circuit breaker and attach DO NOT OPERATE tag.
5. Remove fuses for power, sensing and control transformers.
6. Attach DO NOT OPERATE tag to generator excitation controls.
7. Remove cover of generator terminal box.
8. Use audio/visual proximity tester to verify de-energized; add ground straps.

⚠ Personal injury or death can result from electrocution; the megohmmeter applies a high voltage.

Tools: 9U-6003 Megohmmeter

1. Take the generator out of service.
2. Visually inspect generator for moisture; dry the unit first if moisture exists.
3. Discharge the capacitance of the windings.
4. Disconnect T0 from ground and regulator sensing leads 20, 22 and 24.
5. Disconnect voltage transformer leads T1, T2, T3 and other sensing leads.
6. Connect megohmmeter RED lead to ground and BLACK lead to T0.
7. Set voltage to 500 V for units 600 V or less; 1000 V for more than 600 V.
8. Use 30/60 Time Resistance Method; record 60 second reading corrected for temperature.

⚠ Do not ground the welder to electrical components such as the ECM or sensors.

1. Stop the engine; turn switched power to OFF.
2. Disconnect the negative battery cable; open battery disconnect switch if provided.
3. Disconnect J1/P1 and J2/P2 connectors from the ECM.
4. Disconnect any component with a microprocessor from the engine harness.
5. Connect welding ground cable directly to the part being welded, close to the weld.
6. Protect the wiring harness from welding debris and spatter.
7. Use standard welding practices to weld the materials.