Caterpillar C27 Engine

⚠ 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.

⚠ Replace drive belts for multiple groove pulleys in matched sets

1. Remove the belt guard.
2. Loosen the pulley mounting bolt and adjusting nut.
3. Move the pulley to adjust fan drive belt tension.
4. Tighten the adjusting nut, then the mounting bolt.
5. Reinstall the belt guard.
6. For alternator belt: loosen mounting bolts (2),(3),(4) and adjusting nuts (1).
7. Turn adjusting nuts (1) to increase or decrease tension.
8. Tighten adjusting nuts and mounting bolts; reinstall the guard.
9. Check new belt tension again after 30 minutes at rated rpm.

⚠ Hot oil and hot components can cause personal injury

⚠ Do not fill oil filters with oil before installing them

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

1. Run engine to normal temperature, then stop it.
2. Drain crankcase oil using drain valve or drain plugs; clean and install drain plugs.
3. Remove the oil filter with a 1U-8760 Chain Wrench.
4. Cut the filter open with a 175-7546 Oil Filter Cutter Gp and inspect for metal debris.
5. Clean the filter mounting base sealing surface.
6. Apply clean engine oil to the new filter gasket.
7. Install the oil filter and tighten by hand per the instructions on the filter.
8. Fill the crankcase with recommended oil to between ADD and FULL marks.
9. Start engine and run at LOW IDLE for two minutes; inspect for leaks.
10. Stop engine, wait ten minutes, and recheck oil level.

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

1. Turn the priming pump plunger counterclockwise to unlock it.
2. Manually pump the plunger to fill fuel lines and fuel filters.
3. Continue pumping until a strong resistance is felt.
4. Push in the plunger and lock by turning clockwise.
5. Start the engine at low idle.
6. If the engine runs rough, run at low idle until it runs smoothly.

⚠ Fuel leaked onto hot surfaces can cause a fire

1. Stop engine and turn start switch to OFF.
2. Shut off the fuel tank supply valve.
3. Open drain valve to drain fuel; close drain valve.
4. Remove the fuel filter bowl and wash with clean diesel fuel.
5. Remove the fuel filter; clean the base sealing surface.
6. Apply clean diesel fuel to the new filter gasket.
7. Install the new filter; tighten an additional 3/4 turn by hand.
8. Install the clean fuel filter bowl.
9. Open the fuel tank supply valve.
10. Start engine, run one minute, stop, and check for leaks.

1. Monitor bowl daily for signs of water.
2. Open the self-ventilated drain and catch the draining water in a suitable container.
3. Dispose of the water properly.
4. Close the drain securely to prevent air entering the fuel system.

⚠ Do not fill the secondary fuel filter with fuel before installing

⚠ Do not loosen fuel lines at the fuel manifold or ECM

1. Relieve residual fuel pressure by loosening one fuel supply connection.
2. Remove the used fuel filter.
3. Clean the filter base sealing surface; remove all old gasket.
4. Apply clean diesel fuel to the new filter gasket.
5. Spin the new filter onto the base until the gasket contacts.
6. Tighten an additional 3/4 turn by hand; do not overtighten.

⚠ Do not allow winding temperature to exceed 85 °C

⚠ Use a forced air oven, not radiant

1. Do not operate the generator if windings are wet.
2. For self-circulating air method: run the engine with generator load disconnected and operate the space heaters.
3. For oven method: place the generator in a forced air drying oven for four hours at 65 °C (149 °F).
4. Do not allow winding temperature to exceed 85 °C (185 °F).
5. Recheck insulation resistance after drying.

⚠ Do not mix greases

Tools: Grease gun

1. If already equipped with a visible grease point, go to the greasing step.
2. Remove the louver assembly or rear plate from the generator housing.
3. Remove the top grease pipe plug and the lower grease pipe plug.
4. Install a grease fitting in the grease pipe.
5. Grease the bearings with 2S-3230 Bearing Lubricant; do not mix greases.
6. Wipe off excess grease; remove the fitting and install the plug.
7. Operate the generator for one hour to purge excess grease.
8. Stop the engine; install the plug in the bottom grease pipe.
9. Install the louver assembly or rear plate.