Caterpillar C4.4 Generator Set

⚠ Only qualified service personnel should perform this maintenance

⚠ Hot engine components can cause burns

1. Initial valve lash adjustment recommended at the first scheduled oil change.
2. Ensure the engine cannot be started while this maintenance is performed.
3. Do not use the starting motor to turn the flywheel.
4. Allow valves to cool before measuring valve lash.
5. Refer to the Service Manual for the complete valve lash adjustment procedure.

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

⚠ Wear eye protection at all times during testing

⚠ Test fluid can pierce the skin and cause serious injury

Tools: 8S-2245 Injector Cleaning Tool Group

1. Isolate each fuel injection nozzle one at a time to determine the malfunctioning nozzle.
2. Start the engine.
3. Loosen each fuel line nut one at a time at the fuel injection pump.
4. Use a cloth to prevent fuel spraying on hot exhaust components. Tighten each nut before loosening the next.
5. A faulty nozzle is indicated when exhaust smoke is partially or completely eliminated and performance is unaffected.
6. Remove suspected nozzle and install a new nozzle to determine if removed nozzle is faulty.
7. Clean, inspect and test nozzles. Do not use a wire brush. Use 8S-2245 Injector Cleaning Tool Group.

⚠ Personal injury or death can result from high voltage

⚠ Make sure the unit is off-line, locked out or tagged DO NOT OPERATE

⚠ Make sure all capacitors are discharged

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.
2. Connect the voltmeter to the low voltage winding. Connect a second transformer to T1 and T3 if available.
3. Connect the secondary terminals corresponding to T2 of both transformers together.
4. Disconnect wires "E+" and "E-" from the voltage regulator. Disconnect the generator from the load.
5. Connect a 12 VDC automotive battery to wires "E+" and "E-".
6. Measure AC voltage across low voltage terminals for T1-T2, T2-T3 and T3-T1. Record the voltages.

⚠ Personal injury or death can result from electrocution

⚠ Do not touch the instrument leads without first discharging them

⚠ When finished testing also discharge the generator windings

Tools: 142-5055 Insulation Tester Megohmmeter

1. Isolate the generator. Ensure windings are free of moisture and at room temperature.
2. Main Armature (Stator L4): open the line circuit breaker or load connections T1, T2, T3, T0.
3. Prevent wires from contacting each other or ground. Isolate main armature from the voltage regulator.
4. Connect one test lead to the generator enclosure (ground) and the other to generator lead T0.
5. Insulation resistance must be one megohm or more.
6. Exciter Field (Stator L1): disconnect wires 5+ and 6-.
7. Connect megohmmeter between generator enclosure (ground) and exciter field lead (5+ or 6-).
8. Exciter field insulation resistance must be a minimum of 0.25 megohm (250000 ohms).
9. Exciter Armature (Rotor L2): disconnect the three wires of the exciter armature from the rectifier blocks.
10. Connect one test lead to the rotor shaft and the other to any one exciter field lead.
11. Insulation resistance must be a minimum of 0.25 megohm (250000 ohms).

⚠ A shorted diode can cause damage to the exciter rotor

⚠ Check the exciter rotor if a diode is shorted

Tools: Digital multimeter with diode range

1. Set the digital multimeter on the diode range. Remove all leads from the rectifier block.
2. Negative block: place red lead on negative "-" terminal (1), black lead on AC terminals (2), (3), (4). Readings should be 0.4 to 1.0.
3. Negative block: place black lead on negative "-" terminal (1), red lead on AC terminals (2), (3), (4). Meter should read "OL" (overload).
4. Positive block: place red lead on positive "+" terminal (1), black lead on AC terminals (2), (3), (4). Meter should read "OL".
5. Positive block: place black lead on positive "+" terminal (1), red lead on AC terminals (2), (3), (4). Readings should be 0.4 to 1.0.
6. If any meter reading does not fall within the given ranges, replace the rectifier block.

⚠ A battery with a low charge will freeze more easily than a battery with a full charge

1. Inspect the alternator for loose connections and proper battery charging.
2. Inspect the ammeter (if equipped) during engine operation.
3. Check the alternator and the battery charger for proper operation.
4. Make repairs as required. Refer to the Service Manual.

⚠ Replace belts in matched sets for multiple drive belts

Tools: 144-0235 Belt Tension Gauge

1. Inspect the belts for wear and for cracking. Replace belts that are worn or damaged.
2. Install gauge (1) at center of belt between alternator and crankshaft pulley.
3. Check tension: new belt 400 N (90 lb) to 489 N (110 lb).
4. Used belt (30 minutes or more at rated speed): 267 N (60 lb) to 356 N (80 lb).
5. If twin belts are installed, check and adjust tension on both belts.
6. Loosen mounting bolts (2) and adjusting bolt (1).
7. Move alternator to increase or decrease belt tension.
8. Tighten adjusting bolt (1). Tighten mounting bolts (2) to specified torque.

⚠ Batteries give off combustible gases which can explode

⚠ Remove the battery cover before any servicing is attempted

⚠ Always recycle a battery. Never discard a battery

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

⚠ All lead-acid batteries contain sulfuric acid which can burn skin and clothing

⚠ Always wear a face shield and protective clothing

Tools: 245-5829 Coolant Battery Tester Refractometer

1. Remove the filler caps. Maintain the electrolyte level to the "FULL" mark.
2. Use distilled water if water must be added.
3. Check condition of electrolyte with 245-5829 Coolant Battery Tester Refractometer.
4. Clean battery case with baking soda and water or ammonia and water mixture.
5. Rinse battery case thoroughly with clean water.
6. Clean terminals and cable clamps with fine grade sandpaper.
7. Coat clamps and terminals with 5N-5561 Silicone Lubricant, petroleum jelly or MPGM.

⚠ Removing battery cables with the battery cover in place may cause a battery explosion

1. Turn start switch to OFF. Turn ignition switch OFF and remove key.
2. Disconnect negative battery terminal at the battery that goes to the start switch.
3. When four 12 volt batteries are involved, disconnect negative side of two batteries.
4. Tape the leads to prevent accidental starting.
5. Reverse the steps to reconnect all of the cables.

⚠ Pressurized System: Hot coolant can cause serious burns

⚠ Dispose of used engine coolant properly or recycle

Tools: 9S-8140 Pressurizing Pump

1. Stop engine and allow to cool. Loosen filler cap slowly, relieve pressure, remove cap.
2. Open drain cock or remove drain plug (1) on engine and on radiator. Allow coolant to drain.
3. Flush cooling system with clean water to remove any debris.
4. Close drain valve, clean drain plugs and install drain plugs.
5. Fill with clean water and install cooling system filler cap.
6. Run engine at low idle until temperature reaches 49 to 66 C (120 to 150 F).
7. Stop engine. Drain water and flush again. Close valve and install drain plugs.
8. Fill with Extended Life Coolant (ELC). Do not install filler cap.
9. Run engine at low idle, then high idle for one minute to purge air. Stop engine.
10. Maintain coolant within 13 mm (0.5 inch) of bottom of filler pipe or sight glass level.
11. Clean filler cap and inspect gasket. Pressure test with 9S-8140 if gasket not damaged.
12. Start engine. Inspect cooling system for leaks and proper operating temperature.

⚠ Use only Cat ELC Extender with Cat ELC

⚠ Do NOT use conventional supplemental coolant additive (SCA) with Cat ELC

⚠ Check the cooling system only when the engine is stopped and cool

1. Loosen cooling system filler cap slowly to relieve pressure. Remove cap.
2. It may be necessary to drain enough coolant to add the Cat ELC Extender.
3. Add Cat ELC Extender according to requirements for your cooling system capacity.
4. Clean filler cap. Inspect gaskets. Replace cap if gaskets are damaged. Install cap.