Caterpillar C27 Generator Set

1. Remove the fuel filters.
2. Cut the fuel filters open.
3. Inspect the fuel filter before the filter warms. The inspection will show that the filter is filled with particles of either ice or wax.

⚠ Personal injury or death can result from electrocution

⚠ Do not touch instrument leads before discharging them

Tools: 300-8648 Insulation Testing Gp

1. Take the generator out of service and inspect visually for moisture.
2. Discharge the capacitance of the windings.
3. Disconnect T0 from ground and disconnect regulator sensing leads.
4. Connect insulation tester RED lead to ground and BLACK lead to T0.
5. Set 500 V for units 600 V or less; set 1000 V for units more than 600 V.
6. Apply voltage and observe readings at 30 seconds and 60 seconds.
7. Record the 60 second reading, temperature and humidity; remove voltage.
8. Evaluate readings against previous readings taken under similar conditions.

Tools: Digital multimeter

1. Set the digital multimeter on the diode range and remove all rectifier leads.
2. For negative block: place red lead on negative terminal, black lead on AC1, AC2, AC3; readings should be 0.4 to 1.0.
3. For negative block: place black lead on negative terminal, red lead on AC1, AC2, AC3; meter should read OL.
4. For positive block: place red lead on positive terminal, black lead on AC1, AC2, AC3; meter should read OL.
5. For positive block: place black lead on positive terminal, red lead on AC1, AC2, AC3; readings should be 0.4 to 1.0.
6. Replace the rectifier block if any reading is out of range.

Tools: Ohmmeter, Test light

1. Place an ohmmeter across the varistor; resistance should be a minimum of 15000 ohms.
2. Alternatively, disconnect either lead of the varistor.
3. Place a test light across the varistor; the lamp should not light.
4. Reverse the test light; the lamp should still not light.
5. Replace the varistor if the lamp lights in either direction.

⚠ High voltage can cause severe injury or death

Tools: 6V-7070 Digital Multimeter, 146-4080 Digital Multimeter (RS232)

1. Place engine control switch in OFF; tag all starting controls.
2. Disconnect batteries or disable the starting system.
3. Disconnect the winding being tested from other components.
4. Measure resistance of exciter armature L2 (less than 0.1 ohm).
5. Measure main armature L4 (less than 0.1 ohm) and pilot exciter L5 (less than 0.1 ohm).
6. Measure exciter field L1 (approximately 3.0 to 6.0 ohms) and main field L3 (approximately 1.25 to 2.0 ohms).
7. Confirm no continuity to ground and no continuity between windings.

⚠ All lead-acid batteries contain sulfuric acid which can burn the skin and clothing. Always wear a face shield and protective clothing when working on or near batteries.

Tools: 245-5829 Coolant Battery Tester Refractometer

1. Remove the filler caps; maintain the electrolyte level to the FULL mark on the battery.
2. Use distilled water, or clean water low in minerals if distilled water is not available. Do not use artificially softened water.
3. Check the condition of the electrolyte with the 245-5829 Coolant Battery Tester Refractometer.
4. Keep the batteries clean; clean the battery case with a baking soda/water or ammonia/water solution and rinse with clean water.
5. Use fine grade sandpaper to clean terminals and cable clamps until surfaces are bright.
6. Coat the clamps and terminals with 5N-5561 Silicone Lubricant, petroleum jelly or MPGM.

⚠ The battery cover should be removed before any servicing is attempted.

⚠ Removing the battery cables or batteries with the cover in place may cause a battery explosion resulting in personal injury.

1. Switch the engine to the OFF position; turn the ignition switch OFF and remove the key and all electrical loads.
2. Disconnect the negative battery terminal at the battery that goes to the start switch; ensure the cable cannot contact the terminal.
3. Tape the leads in order to help prevent accidental starting.
4. Proceed with necessary system repairs; reverse the steps in order to reconnect all cables.

⚠ Replace belts that are worn or damaged. For multiple drive belts, replace belts in matched sets.

1. Remove the belt guard. Inspect the condition and adjustment of the alternator belts and accessory drive belts.
2. Check belt tension by applying 110 N (25 lb ft) of force midway between the pulleys; a correctly adjusted belt deflects 9 mm to 15 mm.
3. To adjust an alternator belt, slightly loosen mounting bolt (2), mounting bolt (3) and adjusting nut (1).
4. Move the pulley in order to adjust the belt tension.
5. Tighten the adjusting nuts and mounting bolts; refer to the Specifications, SENR3130 for proper torques.
6. Install the belt guard. If new belts are installed, check the belt tension again after 30 minutes at rated rpm.

⚠ Do not leave an empty SCA maintenance element on a system that is filled with ELC. The element housing may corrode and leak causing an engine failure.

⚠ Improper or incomplete rinsing of the cooling system can result in damage to copper and other metal components.

⚠ The cooling system cleaner must be thoroughly flushed from the cooling system. Cooling system cleaner that is left in the system will contaminate the coolant. The cleaner may also corrode the cooling system.

Tools: Caterpillar cleaner for cooling systems, 5P-3413 Pipe Sealant, Suitable containers to collect fluids

1. Drain the coolant into a suitable container.
2. Dispose of the coolant according to local regulations.
3. If equipped, remove the empty SCA maintenance element and the element base. Plug the coolant lines or bypass the coolant lines.
4. Flush the system with clean water in order to remove any debris.
5. Use Caterpillar cleaner for cooling systems in order to clean the system. Follow the instructions on the label.
6. Drain the cleaner into a suitable container. Flush the cooling system with clean water.
7. In systems with heavy deposits, disconnect the hoses. Clean deposits and debris from the hoses and fittings. Install the hoses and tighten the hose fittings.
8. Fill the cooling system with clean water and operate the engine until the engine is warmed to 49 C to 66 C (120 F to 151 F).
9. Drain the cooling system into a suitable container and flush the cooling system with clean water.
10. Repeat Steps 8 and 9 until the system is completely clean.
11. Fill the cooling system with the Cat ELC.
12. Operate the engine until the engine is warmed. While the engine is running, inspect the engine for leaks. Tighten hose clamps and connections in order to stop any leaks.
13. Attach the Special Publication, PEEP5027, "Label" to the cooling system filler for the engine in order to indicate the use of Cat ELC.

⚠ Hot coolant can cause serious burns. Loosen the pressure cap slowly to relieve pressure.

⚠ Use only cooling system cleaners approved for Caterpillar engines.

Tools: 9S-8140 Pressurizing Pump

1. Stop the engine and allow the engine to cool. Loosen the filler cap slowly to relieve pressure; remove the cap.
2. Open the cooling system drain valve or remove a drain plug; allow the coolant to drain.
3. Flush the cooling system with clean water in order to remove any debris.
4. Close the drain valve; clean and install the drain plugs.
5. Fill with a mixture of clean water and Cat Fast Acting Cooling System Cleaner; install the filler cap.
6. Start and run the engine at low idle for a minimum of 30 minutes; coolant temperature should be at least 82 °C (180 °F).
7. Stop the engine and allow to cool; drain, flush with clean water and close the drain valve.
8. Fill the cooling system with coolant/antifreeze; refer to Refill Capacities and Recommendations.

⚠ Hot coolant can cause serious burns.

⚠ Clean water only is needed when ELC is drained and replaced.

Tools: 9S-8140 Pressurizing Pump

1. Stop the engine and allow the engine to cool. Loosen the filler cap slowly to relieve pressure; remove the cap.
2. Open the drain valve or remove drain plugs; allow the coolant to drain.
3. Flush the cooling system with clean water in order to remove any debris.
4. Close the drain valve; clean and install the drain plugs.
5. Fill the cooling system with clean water; install the filler cap.
6. Start and run the engine at low idle until temperature reaches 49 to 66 °C (120 to 150 °F).
7. Stop the engine and allow to cool; drain, flush with clean water and close the drain valve.
8. Fill the cooling system with Extended Life Coolant (ELC); refer to Refill Capacities and Recommendations.

⚠ Use only Cat Extended Life Coolant (ELC) Extender with Cat ELC.

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

1. Loosen the cooling system filler cap slowly in order to relieve pressure; remove the cap.
2. Drain enough coolant from the cooling system if necessary to add the Cat ELC Extender.
3. Add Cat ELC Extender according to the requirements for your engine's cooling system capacity.
4. Clean the cooling system filler cap and inspect the gaskets.
5. Replace the filler cap if the gaskets are damaged; install the filler cap.