Caterpillar 3126B Generator Set

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

1. Check belt tension initially between the first 20 to 40 hours of engine operation, with the engine stopped.
2. Apply 110 N (25 lb ft) of force midway between the pulleys; a correctly adjusted belt will deflect 9 mm (0.35 inch) to 15 mm (0.59 inch).
3. For alternator belt: slightly loosen mounting bolts and adjusting bolt, move pulley to adjust tension, then tighten.
4. For water pump belt: slightly loosen mounting bolt and adjusting bolt, adjust tension with a square drive in square hole, then tighten.
5. Install the belt guard.
6. If new belts are installed, check tension again after 30 minutes of operation at rated rpm.

⚠ Only qualified service personnel should perform this maintenance.

⚠ Ensure the engine cannot be started while this maintenance is being performed.

⚠ Hot engine components can cause burns.

1. Ensure the engine cannot be started while this maintenance is performed.
2. Ensure the engine is stopped and allow the valves to cool before measuring.
3. Perform the initial valve lash adjustment at the first scheduled oil change.
4. Refer to the Service Manual for the complete valve lash adjustment procedure.

1. Turn cruise control switch to OFF position.
2. Move SET/RESUME switch to either position and hold.
3. Record two-digit flash codes: short pause between digits, long pause between codes.
4. Refer to Engine Diagnostics table in the O & M manual and consult your local Caterpillar dealer.

⚠ Do not use a high concentration of caustic cleaner.

Tools: Steam cleaner, Compressed air

1. Remove the core.
2. Turn the core upside-down to remove debris.
3. Back flush the core with cleaner (Hydrosolv).
4. Steam clean the core and flush the fins.
5. Wash with hot soapy water and rinse.
6. Dry with compressed air in reverse direction of normal flow.
7. Inspect and pressure test the core.
8. Install the core.

⚠ Batteries give off combustible gases which can explode.

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

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

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

Tools: 1U-7298 or 1U-7297 Coolant/Battery Tester

1. Remove the filler caps and maintain electrolyte to the FULL mark.
2. Use distilled water if water must be added.
3. Check electrolyte condition with 1U-7298 or 1U-7297 tester.
4. Keep the batteries clean.
5. Clean battery case with baking soda/water or ammonia/water solution.
6. Rinse with clean water.
7. Clean terminals and clamps with fine sandpaper.
8. Coat clamps and terminals with 5N-5561 Silicone Lubricant, petroleum jelly or MPGM grease.

⚠ Connection or disconnection of battery cables may cause an explosion.

1. Turn the start switch and ignition switch to OFF and remove the key.
2. Disconnect the negative battery terminal at the battery that goes to the start switch.
3. With four 12 volt batteries, disconnect the negative side of two batteries.
4. Tape the leads to prevent accidental starting.
5. Proceed with repairs; reverse steps to reconnect.

⚠ Use of standard belts on this engine may cause an explosion. Only non-static belts should be used.

1. Remove the belt guard.
2. Inspect the condition and adjustment of the alternator and accessory drive belts.
3. Apply 110 N (25 lb ft) of force midway between the pulleys.
4. The correct deflection is 9 mm (0.35 inch) to 15 mm (0.59 inch).
5. To adjust, slightly loosen the mounting bolt and adjusting nut.
6. Move the pulley to adjust belt tension.
7. Tighten the adjusting nuts and the mounting bolts.
8. Install the belt guard.

⚠ Use of standard belts on this engine may cause an explosion. Only non-static belts should be used.

1. Remove the belt.
2. Inspect the belt tensioner for unusual noise, excessive looseness and/or shaking of the bearings.
3. Inspect the other pulleys and idlers for unusual noise, excessive looseness and/or shaking of the bearings.

⚠ Do not leave an empty SCA filter on an ELC system.

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

1. Drain the coolant into a suitable container.
2. Dispose of the coolant according to local regulations.
3. Remove the empty SCA filter and remove the filter 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 to clean the system. Follow the instruction on the label.
6. Drain the cleaner into a suitable container. Flush the cooling system with clean water.
7. Fill the cooling system with clean water and operate the engine until warmed to 49° to 66°C (120° to 150°F).
8. Drain the cooling system and flush with clean water.
9. Repeat the fill/flush steps until the system is completely clean.
10. Fill the cooling system with the Caterpillar premixed ELC.
11. Attach the Label (PEEP5027) to the cooling system filler to indicate use of Caterpillar ELC.

⚠ Do not tap or strike the filter element.

⚠ Do not wash the filter element.

Tools: 60 watt blue light

1. Visually inspect the primary element before cleaning; discard damaged elements.
2. Pressurized air: use filtered, dry air with a maximum pressure of 207 kPa (30 psi); begin with the clean side (inside).
3. Aim the hose so air flows inside the element along the length of the filter.
4. Vacuum cleaning: recommended prior to vacuum cleaning; will not remove carbon and oil deposits.
5. Inspect the clean, dry element with a 60 watt blue light in a dark room for tears or holes.
6. Discard any element that has tears, holes, or damaged pleats, gaskets or seals.
7. Store unused elements wrapped in Volatile Corrosion Inhibited (VCI) paper in a dry location.

⚠ Hot coolant can cause serious burns.

⚠ Dispose of used engine coolant properly or recycle.

⚠ Fill the cooling system no faster than 19 L (5 US gal) per minute to avoid air locks.

Tools: 9S-8140 Pressurizing Pump

1. Drain: stop the engine, allow to cool, loosen and remove the filler cap.
2. Open the drain valve (or remove a drain plug) and allow the coolant to drain.
3. Flush the cooling system with clean water to remove debris.
4. Close the drain valve and install clean drain plugs.
5. Fill with clean water and Caterpillar Fast Acting Cooling System Cleaner (0.5 L per 15 L capacity).
6. Start and run the engine at low idle for a minimum of 30 minutes; coolant temperature at least 82 C (180 F).
7. Stop, cool, drain water and flush with clean water.
8. Fill the cooling system with coolant/antifreeze.
9. Run the engine at low idle then 1500 rpm for one minute to purge air.
10. Check coolant level within 13 mm (0.5 inch) below the filler pipe.
11. Clean and inspect the filler cap gasket; pressure test with 9S-8140 Pressurizing Pump.