Caterpillar 3408C Generator Set

⚠ Replace belts for multiple groove pulleys in matched sets.

Tools: Belt tension gauge (110 N / 25 lb force)

1. Remove the belt guard.
2. Loosen mounting bolt (2) and adjusting nuts (1).
3. Turn adjusting nuts to increase or decrease belt tension.
4. Check deflection is 13 to 19 mm with 110 N applied midway.
5. Tighten the adjusting nuts; tighten the mounting bolt.
6. Reinstall the belt guard.
7. Check adjustment again after 30 minutes at rated rpm if new belts.

⚠ Do not use a high concentration of caustic cleaner to clean the core.

⚠ Maximum air pressure at the nozzle must be less than 205 kPa (30 psi).

Tools: Pressure air supply (maximum 205 kPa / 30 psi at nozzle)

1. Remove the core. Refer to the Service Manual for the procedure.
2. Turn the aftercooler core upside-down in order to remove debris.
3. Back flush the core with cleaner (1U-5490 or 174-6854 Hydrosolv).
4. Steam clean the core to remove residue; flush the fins.
5. Wash the core with hot, soapy water; rinse thoroughly with clean water.
6. Dry the core with compressed air in the reverse direction of normal flow.
7. Inspect the core for cleanliness; pressure test; repair if necessary.
8. Install the core. Refer to the Service Manual for the procedure.

⚠ All lead-acid batteries contain sulfuric acid; wear face shield and protective clothing.

Tools: 245-5829 Coolant Battery Tester Refractometer

1. Remove the filler caps; maintain the electrolyte to the FULL mark.
2. Add distilled water if necessary; avoid artificially softened water.
3. Check electrolyte condition with the 245-5829 Coolant Battery Tester Refractometer.
4. Clean battery case with baking soda/water or ammonia/water solution; rinse.
5. Clean terminals and cable clamps with fine grade sandpaper.
6. Coat clamps and terminals with 5N-5561 Silicone Lubricant, petroleum jelly or MPGM.
7. Clean the battery case; keep the batteries clean.

⚠ Pressurized System: Hot coolant can cause serious burns.

⚠ Stop the engine and wait until cooling system components are cool.

Tools: 9S-8140 Pressurized Pump Group (filler cap pressure test)

1. Observe coolant level in recovery tank; maintain to COLD FULL mark.
2. Loosen filler cap slowly to relieve pressure; remove the filler cap.
3. Pour proper coolant mixture into tank; do not fill above COLD FULL.
4. Clean filler cap and receptacle; reinstall; inspect system for leaks.
5. Without a recovery tank, maintain level within 13 mm of filler pipe bottom.
6. Clean and inspect filler cap gaskets; replace damaged cap.

⚠ Perform this maintenance with the engine stopped.

⚠ A plugged crankcase breather will cause excessive crankcase pressure.

1. Loosen hose clamp (1) and remove the hose from breather assembly (2).
2. Loosen retaining clamp (3); remove the breather assembly and seal (4).
3. Wash the breather element in clean, nonflammable solvent.
4. Allow the breather element to dry before installation.
5. Install a clean, dry element, the seal, the breather assembly, and the clamp.
6. Install the hose and the hose clamp; refer to SENR3130 for torques.

⚠ Hot oil and hot components can cause personal injury.

⚠ Do not fill the oil filters with oil before installing them.

⚠ Do not crank the engine for more than 30 seconds.

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

1. Run the engine at normal operating temperature, then stop the engine.
2. Drain the crankcase through the drain valve or the oil 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; inspect for debris.
5. Clean the filter mounting base sealing surface; remove all old gasket.
6. Apply clean engine oil to new filter gasket; install filter hand tight.
7. Fill crankcase between the ADD mark and the FULL mark on the gauge.
8. Run engine at low idle two minutes; inspect filter for leaks; check level.

⚠ Wear protective glasses or face shield and protective clothing to prevent burns.

⚠ An improperly operating valve rotator will accelerate valve face and valve seat wear.

1. Perform after the engine valve lash is set, before valve covers are installed.
2. Start the engine according to Engine Starting procedure.
3. Operate the engine at low idle.
4. Observe the top surface of each valve rotator.
5. The valve rotators should turn slightly when the valves close.
6. If a valve fails to rotate, consult your Caterpillar dealer.

⚠ Do not crank the engine for more than 30 seconds.

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

⚠ Do not let the tops of fuel nozzles turn when the fuel line nuts are loosened or tightened.

1. Unlock the priming pump; operate until resistance is felt.
2. Push in the plunger, and hand tighten the plunger.
3. Crank the engine; if it runs rough, run at low idle until smooth.
4. Open the vent valve on the fuel injection pump housing, if equipped.
5. Operate priming pump until fuel flow is continuous and free of bubbles.
6. Close the vent valve; push in the plunger; hand tighten.
7. Loosen fuel line nuts at valve cover base one at a time; prime until bubble free.
8. Tighten fuel line nuts to 40 ± 7 N·m (30 ± 5 lb ft).

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

⚠ Do not fill the fuel filters with fuel before installing them.

1. Stop the engine; turn the start switch OFF; disconnect the battery.
2. Shut off the fuel tank supply valve to the engine.
3. Open the drain valve to drain fuel from the filter case; close the valve.
4. Loosen the bolt on the filter housing; remove the filter case.
5. Remove the element and wash it in clean, nonflammable solvent.
6. Install the element and the filter case.
7. Tighten the bolt to 24 ± 4 N·m (18 ± 3 lb ft).

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

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

⚠ Do not overtighten the fuel filter.

1. Stop the engine and turn the start switch off or disconnect the battery.
2. Shut off the fuel tank supply valve to the engine.
3. Unlock the fuel priming pump to relieve residual pressure.
4. Remove the used fuel filter and catch excess fuel.
5. Clean the gasket sealing surface; ensure all old gasket is removed.
6. Apply clean diesel fuel to the new fuel filter gasket.
7. Install new filter; tighten until gasket contacts base; hand tighten.
8. Lock the priming pump; open the fuel tank supply valve.

⚠ Turbocharger bearing failures can cause large quantities of oil to enter the air inlet and exhaust systems.

⚠ Do not continue engine operation with a turbocharger bearing failure and significant performance loss.

Tools: Dial indicator

1. Remove exhaust outlet piping and air inlet piping; visually inspect piping for oil.
2. Clean the interior of the pipes to prevent dirt entering during reassembly.
3. Turn compressor and turbine wheels by hand; assembly should turn freely.
4. Inspect wheels for contact with the turbocharger housing.
5. Check compressor wheel cleanliness; oil on the back side may indicate failed oil seal.
6. Use a dial indicator to check shaft end clearance against Service Manual specifications.
7. Inspect the bore of the turbine housing for corrosion.
8. Clean housing with standard shop solvents and a soft bristle brush; fasten piping.

⚠ Rapid deterioration of zinc rods may indicate uncontrolled electrical currents from improperly installed or grounded electrical attachments.

1. Remove the zinc rod.
2. Tap the zinc rod lightly with a hammer.
3. Install a new zinc rod if the rod has deteriorated or flakes.
4. Unscrew or drill the old zinc rod from the plug; clean the plug.
5. Apply 9S-3263 Compound only to the shoulder of the new zinc rod.
6. Coat the external threads of the plug with 5P-3413 Pipe Sealant.
7. Install the zinc rod; refer to the Operation and Maintenance Manual for torque specifications.