This is the factory Caterpillar repair library for the 320C, 320C L, 320C LN and 320C S hydraulic excavators - 5855 pages covering the engine, hydraulic system, power train, undercarriage, electrical system and operator station, split the way Cat dealers use it: Systems Operation, Testing and Adjusting, Troubleshooting, and Specifications with Disassembly and Assembly. One note on coverage, stated plainly because the book itself does it two ways: the machine sections print serial prefixes BBL1-UP, BCN1-UP, BDE1-UP and BEA1-UP on p.14, while p.40 lists a wider set of 16 prefixes for the embedded documents. Real numbers are here - main relief at 34300 ± 490 kPa (4950 ± 72 psi), pilot relief at 4100 ± 200 kPa (595 ± 29 psi), pump case drain limits, cylinder drift limits - plus full schematics and torque specifications.
What's Inside This Caterpillar 320C, 320C L, 320C LN, 320C S Repair Manual
| System | Pages | Key Topics |
|---|---|---|
| Air Inlet and Exhaust System | 1-78 | Air Inlet and Exhaust System - Inspect, Turbocharger - Inspect, Inlet Manifold Pressure - Test, Exhaust Temperature - Test, Air Cleaner, Exhaust Manifold |
| Basic Engine | 79-402 | Finding Top Center Position for No. 1 Piston, Fuel Injection Nozzle - Test, Gear Group (Front) - Time, Engine Crankcase Pressure (Blowby) - Test, Compression - Test, Engine Valve Lash - Inspect/Adjust |
| Cooling System | 403-490 | Cooling System - Check - Overheating, Cooling System - Inspect, Cooling System - Test, Engine Oil Cooler - Inspect, Water Temperature Regulator - Test, Engine Oil Cooler |
| Electrical and Starting System - Systems Operation | 491-1151 | Electrical System, General Information (Electrical System), Power Circuit, Start and Stop Circuit, Starting Aid Circuit, Charging Circuit |
| Electrical and Starting System - Testing and Adjusting | 1152-1557 | Alternator - Test, Battery - Test, Charging System - Test, Electric Starting System - Test, Pinion Clearance - Adjust, General Information (3) |
| Electrical and Starting System - Troubleshooting | 1558-1737 | Service Tools (2), Electrical Component and Connector Locations, Harness and Wire Identification (2), Using Caterpillar Electronic Technician (2), Using Caterpillar Electronic Technician to Determine Diagnostic Codes, Mid 06A - Cid 0145 - Fmi 06 |
| Electrical and Starting System - Specifications / Disassembly and Assembly | 1738-1814 | Alternator and Regulator, Alternator and Regulator (2), Alternator and Regulator (3), Alternator, Alternator - Remove and Install (2), Air Inlet Heater |
| Engine Arrangement | 1815-1900 | General Information, Engine Speed - Check, Engine Performance - Test - Engine Speed, Engine Design, Engine Design (2), System Pressure - Release |
| Frame and Body | 1901-1994 | Swing Hydraulic System, Swing Bearing Movement - Measure, Counterweight, Swing Drive, Upper Frame, Undercarriage Frame |
| Fuel System | 1995-2225 | Governor Actuator Control, Fuel System - Inspect, Air in Fuel - Test, Fuel Injection Nozzle - Test, Fuel Injection Timing - Check, Fuel Quality - Test |
| Hydraulic System - Systems Operation | 2226-2519 | General Information, Main Hydraulic System, Pilot Hydraulic System, Gear Pump (Pilot), Hydraulic Filter (Pilot), Relief Valve (Pilot) |
| Hydraulic System - Testing and Adjusting | 2520-2857 | Check of Proportional Reducing Valve - Troubleshoot - CID 581, Proportional Reducing Valve Sweep - Test - Power Shift, Proportional Reducing Valve - Calibrate - Power Shift, General Testing and Adjusting Information, Visual Inspection, Hydraulic System Pressure - Release |
| Hydraulic System - Troubleshooting | 2858-3001 | General Information (3), Using Service Mode, Visual Inspection (2), Initial Troubleshooting Procedure, Diagnostic Code List, Mid 06A - Cid 1522 - Fmi 03 |
| Hydraulic System - Specifications / Disassembly and Assembly | 3002-4336 | System Pressure - Release, Hydraulic System Pressure - Release (2), Accumulator (Pilot) (2), Accumulator (Pilot) (3), Accumulator (Hydraulic Pilot), Gear Pump (Auxiliary) |
| Implements | 4337-4440 | SmartBoom Hydraulic System, Boom, Boom Bearings and Seals, Bucket Linkage - C-Family, Bucket Linkage - B-Family, Bucket Linkage |
| Lubrication System | 4441-4514 | Engine Crankcase Pressure (Blowby) - Test, Engine Oil Pressure - Test, Engine Oil Pump - Inspect, Excessive Engine Oil Consumption - Inspect, Increased Engine Oil Temperature - Inspect, Crankcase Breather |
| Machine Arrangement | 4515-4527 | Service Intervals, Heating and Air Conditioning Service Publications |
| Operator Station | 4528-5506 | Monitoring System, Operator Monitor, General Information, Air Conditioning System, Refrigerant Compressor, Refrigerant Condenser |
| Power Train | 5507-5591 | Final Drive, Travel on Level Ground - Test - Optional Test, Travel on Level Ground - Test, Duo-Cone Conventional Seals, Final Drive (2), Duo-Cone Conventional Seals - Install (2) |
| Service Equipment and Supplies | 5592-5648 | Cab Pressurization and Filtration System, Required Tools, Manifold Gauge Set (Refrigerant), Manifold Gauge Set (Refrigerant) - Install (2), Manifold Gauge Set (Refrigerant) - Remove (2), Heating and Air Conditioning Service Publications |
| Undercarriage | 5649-5714 | Front Idler, Recoil Spring and Hydraulic Track Adjuster, Hydraulic Track Adjusters, Recoil Spring, Recoil Spring and Hydraulic Track Adjuster - Remove (2), Recoil Spring and Hydraulic Track Adjuster - Install (2) |
| Work Tools | 5715-5730 | Bucket Adjuster, Bucket Adjuster (2), Bucket |
| Torque Specifications | 5731-5779 | General Information, Metric (ISO) Fasteners, English (SAE) Fasteners, Ground Engaging Tool (G.E.T.) Fasteners, Installation of Fittings, Straight Thread O-Ring Fittings |
| Schematics | 5780-5855 | 320C Excavator Hydraulic System - Attachment - Fine Filtration (Interactive) 188-6617-00, Features, Cover Page, Component Location, Tap Location, Fluid Power Symbols |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Main relief valve pressure | 34300 ± 490 kPa (4950 ± 72 psi) | p. 2590 |
| Pilot relief valve pressure | 4100 ± 200 kPa (595 ± 29 psi) | p. 2577 |
| Main pump case drain flow limit (one pump, 35000 kPa) | 17.3 L/min (4.57 US gpm) | p. 2587 |
| Main pump case drain flow limit (two pumps, 35000 kPa) | 26.0 L/min (6.87 US gpm) | p. 2587 |
| Maximum no-load engine speed (test setting) | 1860 ± 50 rpm | p. 2586 |
| Overswing, right swing - new | 1100 mm (43.3 inch) or less | p. 2562 |
| Overswing, right swing - service limit | 1400 mm (55.1 inch) or less | p. 2562 |
| Boom cylinder drift - new | 6.0 mm (0.24 inch) or less | p. 2569 |
| Boom cylinder drift - service limit | 24.0 mm (0.94 inch) or less | p. 2569 |
| Pilot relief valve locknut torque | 49 ± 4.9 N·m (36 ± 4 lb ft) | p. 2577 |
| Pilot accumulator charge pressure at -25 °C | 1490 kPa (216 psi) | p. 2579 |
Caterpillar 320C, 320C L, 320C LN, 320C S Common Problems This Manual Covers
Low hydraulic power and sluggish response, sometimes with the engine bogging or stalling under load
Follow Hydraulic System Troubleshooting in order: filters and restrictions first, then the case drain flow test in Testing and Adjusting - one pump must stay at or under 17.3 L/min (4.57 US gpm) at 35000 kPa (5076 psi) discharge, and no-load engine speed should test at 1860 ± 50 rpm before you blame the pumps.
Manual Section: Hydraulic System - Testing and Adjusting p. 2631Boom drifts down with a loaded bucket parked
Run the boom cylinder drift measurement in Hydraulic System Testing and Adjusting (p.2569): 6.0 mm (0.24 inch) or less is new spec, 12.0 mm (0.47 inch) passes a rebuild, 24.0 mm (0.94 inch) is the service limit. Past that, the manual takes you into cylinder seal replacement in Disassembly and Assembly.
Manual Section: Hydraulic System - Testing and Adjusting p. 2569Hard starting, dead clicks, or intermittent warnings on the monitor
The Electrical And Starting System group is split into Systems Operation, Testing and Adjusting, and Troubleshooting so you can trace batteries, grounds, the charging circuit and sensor wiring step by step instead of swapping parts. Corroded grounds and weak batteries cause most of the phantom warnings on these machines, and the test procedures catch them fast.
Manual Section: Electrical And Starting System - Troubleshooting p. 1558Swing coasts too far past the stop point, or travel feels slow on one side
Measure against the printed limits in Hydraulic System Testing and Adjusting: overswing is 1100 mm (43.3 inch) or less new and 1400 mm (55.1 inch) at service limit (p.2562), and three track revolutions at HIGH speed forward should take 17.0 seconds or less new, 19.0 at service limit (p.2552). Out of spec sends you to the swing or travel motor procedures.
Manual Section: Hydraulic System - Testing and Adjusting p. 2562Frequently Asked Questions
How do I read and clear the diagnostic codes on a Cat 320C?
The 320C is an electronic machine with an ECM, and it reports faults as CID/MID/FMI codes through the monitor. The manual walks you into Service Mode from the monitor panel (p.2228) so you can view active and logged codes, then the Electrical And Starting System Troubleshooting section takes each code to a cause. Clear a code without fixing the wiring or sensor behind it and it comes right back, which is why the troubleshooting procedures matter more than the reset itself. p. 2228
My boom and stick are slow and weak. Where do I start?
Start where the manual starts: cheap restrictions before pump work. Then run the pump case drain flow test from Hydraulic System Testing and Adjusting - at 35000 kPa (5076 psi) discharge pressure, one pump may pass no more than 17.3 L/min (4.57 US gpm) of case drain, 26.0 L/min (6.87 US gpm) for two pumps. Over that, the pump is eating itself. Also verify main relief at 34300 ± 490 kPa (4950 ± 72 psi) before condemning anything. p. 2631
Does this manual cover my serial number?
Check your prefix against the book. The machine sections print BBL1-UP, BCN1-UP, BDE1-UP and BEA1-UP on p.14, and p.40 carries a wider list of 16 prefixes for the embedded documents. The manual covers the 320C, 320C L, 320C LN and 320C S variants, so if your plate shows one of those prefixes you are in the right book. p. 40
Are the actual pressure settings and test specs in here, or just procedures?
Both, with tolerances. Main relief valve setting is 34300 ± 490 kPa (4950 ± 72 psi), pilot relief is 4100 ± 200 kPa (595 ± 29 psi) with a 49 ± 4.9 N·m (36 ± 4 lb ft) locknut torque, max no-load engine speed for testing is 1860 ± 50 rpm, and accumulator charge pressures are tabled by temperature. Every hydraulic performance test has new, rebuild and service limit columns so you know whether a machine passes or needs work. p. 2590
Can I reset the service light or fuel gauge from the cab?
Monitor functions on the 320C, including gauge and display behavior, run through the Service Mode entered from the monitor itself, and the Electrical And Starting System sections cover the monitor system operation and adjustment. The manual does not treat a warning as something to blank out - it treats it as a symptom, gives you the troubleshooting path, and the display clears once the underlying fault is gone. p. 2228
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