Caterpillar 312B L
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar 312B L is a long-reach hydraulic excavator in the mid-size class, produced from the late 1990s through the mid-2000s. It succeeds the 312B and precedes the 312C L. The machine utilizes a Cat 3064T turbocharged diesel engine delivering 63 kW (84 hp) net power. Operating weight ranges from 12,705 kg (28,010 lb) to 14,111 kg (31,110 lb) depending on configuration. Configurations include various boom and stick options, such as a 4300 mm (14'169 ") boom with 2500 mm (8'98 ") or 3000 mm (9'118 ") sticks, and a 2100mm hex stick option.
Across the 312B L generation, the primary focus was on improved serviceability and operator comfort compared to the 312B. Key changes included an ergonomic cab with sliding seat and consoles, a high-contrast LCD instrument panel, and an optional autolubricator. The 312B L matters in the used market because its robust 3064T engine and simple hydrostatic drive system offer lower complexity and repair costs than later electro-hydraulic models. Its availability in long-reach configurations makes it a specialized asset for trenching and utility work.
Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.
Caterpillar 312B L specifications
Engine
| Model | Cat 3064T Diesel Engine |
| Gross Power | 68 kW (91 hp) |
| Net Power | 63 kW (84 hp) |
| Displacement | 259 cu in (4,244 cu cm) |
| Cylinders | 4 |
| Emissions Tier | Not documented for this exact serial range — verify with your dealer |
Weights
| Operating Weight | 12,705 kg (28,010 lb) to 14,111 kg (31,110 lb) varies by configuration/series |
| Ground Pressure | 5.6 psi to 5.51 psi varies by configuration/series |
Dimensions
| Transport Length | 7.6 m (24.92 ft) to 7.61 m (24.97 ft) varies by boom/stick option |
| Transport Width | 8.17 ft (2.49 m) |
| Transport Height | 9.06 ft (2.76 m) |
| Tail Swing Radius | 6.99 ft (2.13 m) |
| Track Shoe Width | 19.69 in (50 cm) |
| Ground Clearance | 1.45 ft (0.44 m) |
| Undercarriage Length | 9.98 ft (3.04 m) |
Performance
| Max Dig Depth | 14.54 ft (4.43 m) to 19.85 ft (6.05 m) varies by boom/stick option |
| Max Reach at Ground | 25.56 ft (7.79 m) to 28.3 ft (8.63 m) varies by boom/stick option |
| Max Dump Height | 19.23 ft (5.86 m) to 20.77 ft (6.33 m) varies by boom/stick option |
| Max Cutting Height | 27.01 ft (8.23 m) to 28.53 ft (8.69 m) varies by boom/stick option |
| Swing Speed | 12 rpm |
| Travel Speed | 5.5 kph (3.42 mph) |
| Drawbar Pull | 22,930 lb (10,401 kg) |
Service capacities (summary)
| Fuel Tank | 66.1 gal (250 L) |
| Hydraulic System/Tank | 42.8 gal (162 L) total; 25.9 gal (98 L) tank |
| Engine Oil | 3.5 gal (13 L) |
| Cooling System | 4.1 gal (16 L) |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
312B L fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with filter) | 13 l (3.4 gal) | Cat DEO or TDTO; SAE 15W-40 for most climates |
| Cooling system | 15.5 l (4.1 gal) | Cat ELC or extended-life coolant |
| Fuel tank | 250 l (66 gal) | Ultra-low sulfur diesel |
| Hydraulic system total AND hydraulic tank | 162 l (42.8 gal) total; 98 l (25.9 gal) tank | Cat HYDO or equivalent ISO 46 hydraulic oil |
| Final drive (each) | 2.5 l (0.66 gal) | Cat TDF or API GL-5 80W-90 gear oil |
| Swing drive | 2.8 l (0.74 gal) | Cat TDF or API GL-5 80W-90 gear oil |
| Pilot/other circuits | Not documented for this exact serial range — verify with your dealer | Not documented for this exact serial range — verify with your dealer |
| Grease (spec only) | N/A | Cat EPM or equivalent lithium-complex grease |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar 312B L maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
Servicing the 312B L beyond the schedule
Predictive Maintenance & Fluid Analysis
Implement the S.O.S program at 1,000-hour intervals to monitor engine oil, hydraulic fluid, and coolant for wear metals and contamination. Check the hydraulic oil sample for particle count and viscosity. Inspect the air filter restriction indicator daily; replace the primary element at 1,000 hours or sooner in dusty conditions. Test coolant SCA concentration at 500 hours to prevent liner pitting. Monitor the pre-start monitoring system for accurate fluid level alerts.
Corrective & Common Repairs
Address hydraulic leaks by inspecting hoses and fittings during the 500-hour service. Replace the cartridge-type hydraulic oil filter, which allows access without submerging hands in oil. Check the engine oil filter mounted upside-down on the cab side for easier replacement. Inspect the swing bearing and bucket linkage pins for wear; the autolubricator excludes these points. Verify track tension to prevent premature undercarriage wear.
Overhaul & Rebuild Points
Plan major overhauls at 2,000 hours with a comprehensive structural inspection of the boom and stick welds. Flush the cooling system and replace the coolant to protect the 3064T engine. Inspect the turbocharger and replace worn belts and hoses. Evaluate the final drive and swing drive oil for metal content; change oil at 1,000 hours. Measure undercarriage components to determine if sprockets, rollers, or tracks require replacement.
Seasonal & Environment Servicing
In cold weather, utilize the factory air-intake grid heater for reliable starts. Check the battery load test regularly. In dusty environments, clean the radiator and oil cooler fins daily and shorten air filter replacement intervals. Inspect the wiper blade storage on the right-hand pillar for proper function. Ensure the cab ventilation system switches between fresh and recirculated air effectively. Verify the hydraulic activation control lever prevents startup when the operator exits.
312B L fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CID 0110 FMI 03 | Engine Coolant Temperature Sensor — Voltage Above Normal | Open circuit in sensor wiring or failed sensor element | Inspect harness for damage; replace sensor if confirmed faulty |
| CID 0110 FMI 01 | Engine Coolant Temperature — Below Normal | Low coolant level or failed thermostat | Check coolant level; test thermostat function |
| CID 0190 FMI 08 | Engine Speed Sensor — Abnormal Frequency | Speed sensor air gap, sensor failure, or tone ring damage | Check sensor gap; test speed sensor and tone ring |
| CID 0041 FMI 03 | 8-Volt DC Supply — Voltage Above Normal | Short to power on 8V reference circuit | Inspect sensors sharing the 8V supply and isolate fault |
| CID 0041 FMI 04 | 8-Volt DC Supply — Voltage Below Normal | Short to ground on 8V reference circuit | Disconnect sensors one at a time to locate short |
| CID 0262 FMI 05 | 5-Volt Supply — Current Below Normal (Open Circuit) | Open circuit in 5V reference circuit | Check wiring continuity and connector integrity |
| CID 0248 FMI 09 | CAT Data Link — Abnormal Update Rate | CAN bus wiring damage or termination fault | Check CAN wiring and measure termination resistance |
| CID 0091 FMI 02 | Throttle Position Sensor — Erratic/Intermittent | Faulty sensor or intermittent wiring connection | Test sensor output; check connector pins for corrosion |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
312B L attachments & work tools
Buckets
Reference capacity ranges from 0.6 yd³ (0.5 m³) to 1.1 yd³ (0.8 m³) depending on application. Typical widths for this class span 18 in (450 mm) to 60 in (1500 mm) for ditching variants. Pin-on mounting is standard; quick coupler compatibility varies by configuration and series.
Hydraulic hammers
Matches the 12-ton class breaker weight range. The machine provides 64 gpm (240 lpm) main implement flow to support medium-duty breakers. Verify specific breaker weight limits against the 312B L operating weight of 31110 lb (14110 kg).
Quick couplers
S-type coupling elements are documented for the 312B L. Compatibility extends to the broader 311-314 excavator range. Verify pin diameter and cylinder bore dimensions for the specific boom/stick option installed.
Thumbs/grapples
Aftermarket thumbs and grapples are available for the 312B L. Attachment mounting points align with the standard bucket cylinder bore of 4 in (100 mm) and stick cylinder bore of 4.8 in (120 mm). Verify hydraulic flow requirements for powered grapples.
Rippers
Rippers are not documented for the 312B L in the provided factory specifications. The machine is configured for general earthmoving and trenching rather than rock ripping. Consult a dealer for specialized rock tooling if required.
Hydraulic-kit notes
The 312B L uses a standard high-pressure hydraulic system with a maximum implement pressure of 4340 psi (29900 kPa). Main implement flow is 64 gpm (240 lpm). Verify auxiliary circuit flow availability for high-demand tools.
All 312B L assemblies by section
Every catalogued assembly group for the Caterpillar 312B L. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Electrical And Starting System
An Attachment
| 5Q***55 | Bracket As | 1 |
1507002 Harness As.
| 15***02 | Harness As | 1 |
1507003 Harness As.
| 15***03 | Harness As | 1 |
1506987 Harness As.
| 15***87 | Harness As. | 1 |
1506988 Switch As.
| 15***88 | Switch As | 1 |
1507004 Wiring Gp-Coupler
| 15***04 | Wiring Group; (Quick Coupler) | 1 |
Hydraulic System
1461473 Control Ar-Coupler
| 14***89 | Lines Group; (Coupler) | 1 |
| 14***73 | Control Ar; (Coupler) | 1 |
| 15***04 | Wiring Group; (Quick Coupler) | 1 |
1354080 Coupler Ar-Quick
| 13***80 | Coupler Ar | 1 |
| 14***48 | Lines Group; (Coupler) | 1 |
| 14***73 | Control Ar; (Coupler) | 1 |
1354082 Coupler Ar-Quick
| 13***82 | Coupler Ar | 1 |
| 14***48 | Lines Group; (Coupler) | 1 |
| 14***73 | Control Ar; (Coupler) | 1 |
1354081 Coupler Ar-Quick
| 13***81 | Coupler Ar | 1 |
| 14***48 | Lines Group; (Coupler) | 1 |
| 14***73 | Control Ar; (Coupler) | 1 |
1354083 Coupler Ar-Quick
| 13***83 | Coupler Ar | 1 |
| 14***48 | Lines Group; (Coupler) | 1 |
| 14***99 | Lines Group; (Coupler) | 1 |
1195414 Bucket Cylinder Gp-Lines &
| 11***14 | Cylinder & Lines Group-Bucket | 1 |
| 12***66 | Lines Group-Bucket Cylinder | 1 |
| 14***15 | Cylinder & Seal Group-Bucket | 1 |
1438015 Bucket Cylinder Gp-Seal &
| 14***15 | Cylinder & Seal Group-Bucket | 1 |
1438158 Cylinder Gp-Bucket
| 14***58 | Cylinder Group-Bucket | 1 |
1461489 Lines Ar-Coupler
| 12***07 | Stick Group | 1 |
| 14***98 | Lines Group; (Coupler) | 1 |
| 14***89 | Lines Ar; (Coupler) | 1 |
1461477 Lines Ar-Coupler
| 12***03 | Stick Group | 1 |
| 14***77 | Lines Ar; (Coupler) | 1 |
| 14***78 | Lines Group; (Coupler) | 1 |
1461478 Lines Gp-Coupler
| 14***78 | Lines Group; (Coupler) | 1 |
1461299 Lines Gp-Coupler
| 14***99 | Lines Group; (Coupler) | 1 |
1461298 Lines Gp-Coupler
| 14***98 | Lines Group; (Coupler) | 1 |
1461488 Lines Gp-Coupler
| 14***88 | Lines Group; (Coupler) | 1 |
1461248 Lines Gp-Coupler
| 14***48 | Lines Group; (Coupler) | 1 |
1461289 Lines Gp-Coupler
| 14***89 | Lines Group; (Coupler) | 1 |
1287566 Lines Gp-Bucket Cylinder
| 12***66 | Lines Group-Bucket Cylinder | 1 |
1211491 Valve Gp-Solenoid
| 12***91 | Valve Group-Solenoid; -Hydraulic Activation Control | 1 |
| 13***45 | Valve Group-Solenoid; (Solenoid) | 1 |
| 13***60 | Valve Group-Solenoid; (Solenoid) | 1 |
1315745 Valve Gp-Solenoid
| 13***45 | Valve Group-Solenoid; (Solenoid) | 1 |
1315760 Valve Gp-Solenoid
| 13***60 | Valve Group-Solenoid; (Solenoid) | 1 |
1315759 Valve Gp-Solenoid
| 13***59 | Valve Group-Solenoid; (Solenoid) | 1 |
1211490 Valve Gp-Solenoid
| 12***90 | Valve Group-Solenoid; -Travel | 1 |
| 13***44 | Valve Group-Solenoid; (Solenoid) | 1 |
| 13***59 | Valve Group-Solenoid; (Solenoid) | 1 |
1315744 Valve Gp-Solenoid
| 13***44 | Valve Group-Solenoid; (Solenoid) | 1 |
1461287 Valve Gp-Solenoid
| 14***87 | Valve Group-Solenoid | 1 |
Implements
1461475 Coupler Gp-Quick
| 14***75 | Coupler Group-Quick; (Coupler) | 1 |
1461474 Linkage Ar-Coupler
| 11***14 | Cylinder & Lines Group-Bucket | 1 |
| 14***74 | Linkage Ar-Coupler; (Coupler) | 1 |
| 14***76 | Linkage Group-Bucket; (Bucket) | 1 |
1461476 Linkage Gp-Bucket
| 14***76 | Linkage Group-Bucket; (Bucket) | 1 |
1276707 Stick Gp
| 12***07 | Stick Group | 1 |
1276703 Stick Gp
| 12***03 | Stick Group | 1 |
Service Equipment And Supplies
1461358 Film Gp
| 14***58 | Film Group | 1 |
312B L serial number reference
The Product Identification Number (PIN) plate is located on the machine's outer frame, typically near the right-hand pillar or engine compartment access point. The prefix is the first three alphanumeric characters of the PIN; the remaining digits constitute the serial sequence.
| Prefix | Identifies | Notes |
|---|---|---|
| 2NS | 312B L | Standard configuration. Production range begins at 2NS00001. Verified by HW Part Store seal kit listings and aftermarket parts catalogs which group 312B & 312B L under this prefix for the 3064 engine application. |
| 3FS | 312B L | Standard configuration. Production range begins at 3FS00001. Verified by HW Part Store seal kit listings and aftermarket parts catalogs which group 312B & 312B L under this prefix for the 3064 engine application. |
| 8JR | 312B L | Standard configuration. Production range begins at 8JR00001. Verified by HW Part Store seal kit listings and aftermarket parts catalogs which group 312B & 312B L under this prefix for the 3064 engine application. |
| 9GR | 312B L | Standard configuration. Production range begins at 9GR00001. Verified by HW Part Store seal kit listings and aftermarket parts catalogs which group 312B & 312B L under this prefix for the 3064 engine application. |
| 9NW | 312B L | Standard configuration. Production range begins at 9NW00001. Verified by HW Part Store blade seal kit listing which explicitly includes 9NW1-UP for the 312B L model. |
Frequently asked questions
What engine does the 312B L use?
The 312B L uses a Cat 3064T turbocharged diesel engine with 4 cylinders, producing 84 hp (63 kW) net power at 1,900 rpm.
What is the operating weight?
Operating weight varies by configuration, ranging from 12,705 kg (28,010 lb) to 14,111 kg (31,110 lb).
What model replaced the 312B L?
The 312C L replaced the 312B L, introducing the C4.2 engine and electro-hydraulic controls.
What 312B L owners discuss
What engine powers the Caterpillar 312B L, and what are its power ratings?
What are the typical hydraulic system pressures and flow rates for the 312B L?
What are the known undercarriage wear patterns and specifications for this machine?
What are the common electrical or sensor issues reported by owners?
What are the common engine quirks or hydraulic behaviors for the 312B L?
What are the fluid capacities and service intervals for the 312B L?
What should be checked when buying a used 312B L?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific 312B L part?
Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.