621 TRACTOR-SCRAPER When Required Caterpillar

(39)Air Intake System

Never service air cleaner elements with engine running.

Service filter elements when RED indicator piston locks in the visible position.

Servicing Primary Element

1. Remove covers.

2. Remove primary elements.

3. Clean inside body.

4. Clean covers.

5. Clean and inspect elements. (See page 29.)

6. Install elements and covers.

7. Reset filter indicator.

If indicator shows RED shortly after cleaning and primary elements have been cleaned 6 to 8 times, change elements.

If a new primary element was used and the indicator shows RED, clean secondary element.

Servicing Secondary Element

1. Remove covers and primary elements.

2. Remove secondary elements.

3. Cover air inlet openings.

4. Inspect precleaner. Clean all parts when necessary.

5. Clean and inspect elements. (See page 29.) Use new gaskets when necessary.

6. Uncover air inlet openings and install secondary elements. Tighten nuts to 20 ± 3 lb. ft. (2,8 ± 0,4 mkg).

7. Install primary elements and covers.

If indicator shows RED shortly after cleaning secondary elements, change elements.

Never use elements with damaged pleats, gaskets or seals.

Have spare elements on hand to use while cleaning and drying used elements.

Cleaning Air Cleaner Elements

Pressure Air - 30 PSI (2 kg/cm²) Maximum

1. Direct air inside element along length of pleats.

2. Direct air outside along length of pleats. Direct air inside along length of pleats.

3. Check element.

Water - 40 PSI (3 kg/cm²) Maximum

1. Direct water inside element along length of pleats.

2. Direct water outside along length of pleats. Rinse element.

3. Air dry thoroughly. Check element.

Detergent

1. Wash in warm water and non-sudsing household detergent.

2. Rinse with clean water, 40 PSI (3 kg/cm²) maximum.

3. Air dry thoroughly. Check element.

Checking Element

1. Insert light inside clean and dry element. Check and discard element if pinholes or tears are found.

2. Wrap and store good elements in a clean dry place.

Do not clean elements by bumping or tapping.

Have spare elements on hand to use while cleaning used elements.

Do not use elements with damaged pleats, gaskets or seals.

(40)Fuel System

Primary Fuel Filter - Change When Fuel Pressure Gauge Registers out

1. Remove cover.

2. Remove element and wash in clean solvent.

3. Dry with pressure air and install.

Final Fuel Filter - Change Elements

1. Remove cover and filter elements.

2. Clean gasket surface.

3. Install new filters. Install cover. Prime fuel system and start engine. Check for leaks.

Priming the Fuel System

1. Open filter housing vent valve.

2. Unlock priming pump.

3. Operate plunger until ...

4. ... flow of fuel from drain line is free of air bubbles.

5. Close vent valve.

6. Lock priming pump.

(41)Cooling System

Whenever draining and refilling the cooling system, always recheck the coolant level when the engine reaches normal operating temperature.

Remove cap slowly to relieve pressure. Maintain coolant level to within 1/2 inch (1 cm) of the bottom of the fill pipe.

Use clean water that is low in scale forming minerals, not softened water.

Never add coolant to an overheated engine. Allow engine to cool first.

Check specific gravity of antifreeze solution frequently in cold weather to assure adequate protection.

Add AVSpare Coolant System Inhibitor. Follow recommendations given on container.

Show/hide table

Inhibitor contains alkali, avoid contact with skin or eyes.

Cleaning the Cooling System

1. Run engine until water temperature gauge registers NORMAL. Park the tractor-scraper on level ground and stop engine.

2. Turn filler cap slowly to relieve pressure, then remove the cap.

3. Open radiator drain valve and drain coolant.

4. Remove drain plug on air compressor and drain coolant.

5. Remove oil cooler drain plug and drain coolant.

6. Close drain valve and install drain plugs. Fill system with cleaning solution. ⁽¹⁾

7. Start and run engine for 1/2 hour.

8. Stop engine and drain cleaning solution. (See steps 3, 4 and 5.)

9. Flush system with clean water until draining water is clear.

10. Close drain valve and install drain plugs. Fill system with neutralizing solution. ⁽²⁾

11. Start engine and run for 10 minutes.

12. Stop engine and drain neutralizing solution. (See steps 3, 4 and 5.)

13. Flush system with clean water.

14. Close drain valve and install drain plugs. Add coolant to proper level.

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⁽¹⁾2 lb. Sodium Bisulphate (NaHSO₄) per 10 gal. water (25 grams per liter).

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⁽²⁾1/2 lb. Sodium Carbonate Crystals (NaCO₃, 10 H₂O) per 10 gal. water (6 grams per liter).

NOTE: Most commercial cooling system cleaners may be used.

(42)Ejector Carrier And Guide Rollers

1. Loosen clamp bolt.

2. Turn adjusting nut to desired positions.

3. Tighten clamp bolt. Rollers are adjusted when ejector operates without binding or rubbing bowl. Repeat procedure for opposite side.

(43)Cutting Edges

1. Raise and block bowl and apron. Stop engine.

2. Remove bolts.

3. Remove section and clean contact surfaces.

4. Use opposite edge if not worn. If both edges are worn change section.

5. Install bolts and tighten to 900 ± 50 lb. ft. (124,5 ± 70 mkg).

6. Start engine and remove blocks.

7. After a few hours of operation, retighten bolts.

(44)Routing Bits

1. Raise and block bowl and apron. Stop engine.

2. Remove bolts.

3. Remove routing bit and clean contact surfaces.

4. Use other end of bit if not worn. If both ends are worn, change bit.

5. Install bolts and tighten.

6. Start engine and remove blocks.

7. After a few hours of operation, retighten bolts.

(45)Hydraulic Cylinder - Shim Adjusted Rod Packing

1. Lower bowl and apron and stop engine.

2. Relieve hydraulic pressure by moving controls with engine stopped.

3. Remove bolts holding gland to cylinder head.

4. Pry or lightly tap gland to remove.

5. Cut and remove one shim.

6. Assemble and test cylinder for leaking.

7. If still leaking remove one more shim. Do not remove more than two shims.

8. Assemble and test for leaking.

9. If still leaking install new packing. See your AVSpare dealer.

(46)Transmission System

Tractor-scraper must be on level ground, parking brake applied, transmission in NEUTRAL with safety lock ON, oil warm and engine running at low idle. Maintain oil level to FULL mark on dipstick.

(47)Differential And Final Drives

Operate tractor-scraper on level ground a few minutes. Maintain oil level to FULL mark on dipstick. Do not drain oil if above FULL.

(48)Cushion Hitch Accumulator

Your AVSpare dealer is equipped to check accumulator nitrogen precharge pressure.