Caterpillar 3306B 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.

⚠ The VR3 regulator is protected by a fuse(s) and a solid-state overcurrent protection. If a fuse becomes open, contact a Caterpillar dealer.

1. Remove the access panel of the generator.
2. Loosen the locknut on the voltage droop potentiometer (1).
3. Remove the protective screw from the voltage level potentiometer (2) and from the voltage gain potentiometer (3).
4. Turn the voltage droop potentiometer (1) counterclockwise to zero droop. Tighten the locknut.
5. Turn the voltage gain potentiometer (3) counterclockwise to zero, then to about 1/4 of full range of clockwise travel.
6. Perform required maintenance on the engine before you start the engine.
7. Start the engine and allow the engine to warm up.
8. Increase engine speed to full governed rated speed (high idle).
9. Set the no-load voltage with the voltage level potentiometer (2) or the voltage adjust rheostat.
10. Close the load circuit breaker and apply full load gradually. Adjust governor control to nameplate frequency or rated speed.
11. If the voltmeter reading increases above no-load voltage, turn the voltage gain potentiometer counterclockwise. If it decreases, turn it clockwise.
12. Remove the load. If necessary, adjust the voltage level potentiometer (2) to obtain desired voltage.
13. Apply the load. Repeat Steps 10 through 12 until the voltage at no load equals the voltage at full load.
14. Tighten the locknuts. Install the protective screws and the access panel of the generator.

⚠ Do not operate the generator set at a speed higher than one-half of the rated speed.

Tools: 6V-7070 Digital Multimeter, 12 VDC battery, Potential Transformer

1. Stop the generator. Connect the potential transformer's high voltage winding to generator terminals T1 and T2. Connect the voltmeter to the low voltage winding.
2. Disconnect wires F1+ and F2- from the voltage regulator. Disconnect the generator from the load.
3. Connect a 12 VDC automotive battery to wires F1+ and F2-.
4. Operate the generator set at half the rated speed.
5. Measure the AC voltage across the low voltage terminals corresponding to T1-T2, T2-T3, and T3-T1. Record the voltages.
6. Monitor the voltage between any two locations, then decrease the generator set speed by 10 percent and increase it by 10 percent.
7. The measured voltages should be nearly equal and should measure a minimum of 85 VAC.
8. When speed is decreased by 10 percent the voltages should decrease by 10 percent; when increased by 10 percent the voltages should increase by 10 percent.

Tools: 6V-7070 Digital Multimeter, 146-4080 Digital Multimeter (RS-232)

1. Touch the red ohmmeter lead to the rectifier terminal marked '+'.
2. Touch the black ohmmeter lead to terminals AC1, AC2, and AC3; the meter should indicate an open circuit or high resistance.
3. Touch the black ohmmeter lead to the rectifier terminal marked '+'.
4. Touch the red ohmmeter lead to terminals AC1, AC2, and AC3; the meter should indicate a good diode or low resistance.
5. Touch the black ohmmeter lead to the rectifier terminal marked '-'.
6. Touch the red ohmmeter lead to terminals AC1, AC2, and AC3; the meter should indicate an open circuit or high resistance.
7. Touch the red ohmmeter lead to the rectifier terminal marked '-'.
8. Touch the black ohmmeter lead to terminals AC1, AC2, and AC3; the meter should indicate a good diode or low resistance.
9. If the meter does not indicate the expected result, the rectifier is bad. Replace the rectifier.

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.

Tools: Ohmmeter, Test Light

1. Using an ohmmeter, place the ohmmeter across the varistor. The resistance should be a minimum of 15000 ohms.
2. Disconnect either lead of the varistor (CR7).
3. Place the test light across the varistor.
4. Observe the results. The lamp should not light.
5. Reverse the test light.
6. Observe the results. The lamp should not light.
7. If the test light illuminates in either direction, there is a short in the varistor. Replace any faulty varistors with comparable operating characteristics.

⚠ 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.

Tools: Grease fitting, 8F-9866 Grease gun

1. Remove either the louver assembly or the rear plate from the rear of the generator housing.
2. Remove the top grease pipe plug and remove the lower grease pipe plug.
3. Install a grease fitting in the grease pipe.
4. Grease the shielded ball bearings with 2S-3230 Bearing Lubricant (53.28 mL (1.8 ounces) to 59.20 mL (2.0 ounces)).
5. Wipe off the excess grease. Remove the top grease fitting. Install the plug.
6. Operate the generator for one hour to allow the grease to expand and force excess grease from the cavity.
7. Stop the engine. Install the plug in the bottom grease pipe and wipe off the excess grease.
8. Install the louver assembly or install the rear plate.

⚠ 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.