Caterpillartrack-type loadertrack loader
Caterpillar 951B
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar 951B is a crawler-type loader introduced in 1967. This machine class features a four-cylinder Caterpillar D330 engine delivering 85 hp (63 kW) flywheel horsepower. Depending on the serial number prefix, configurations vary: USA-built units (79H, 86J) and Japan-built units (15H, 32F, 72J, 78J) may feature direct drive or powershift transmissions with pedal steer. The machine operates with a standard operating weight of approximately 22,100 lb (10,000 kg), featuring a bucket capacity of roughly 1.15 m³ (0.15 yd³).
Evolution across the 951B series included the addition of hydraulic track adjusters and automatic bucket positioners on specific 32F and 8/6J units. Later production iterations introduced sealed and lubricated tracks (SALT) to improve undercarriage longevity. Today, the 951B remains a significant machine in the used parts market due to its high production volume—estimated at over 17,200 units—and the widespread availability of aftermarket components for its engine, final drives, and undercarriage assemblies.
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 951B specifications
Engine
| Engine Model | Caterpillar D330 |
| Net Power | 85 hp (63 kW) FWHP; varies by configuration/series (70 hp reported for early 951 units) |
| Engine Configuration | Four-cylinder |
| Standard Features | Electric start; hydraulic track adjuster (on specific serial ranges); sealed loader linkage (on specific serial ranges) |
Weights
| Operating Weight | 22,000 lb to 22,100 lb (varies by configuration/series) |
Dimensions
| Operating Length | 15 ft 185 in (4.7 m) |
| Operating Width | 6 ft 5 in to 6 ft 6 in (varies by configuration/series) |
| Operating Height | 9 ft 108 in (2.75 m) |
| Track Gauge | 60 in (152 cm) available on 69H, 32F, and 86J prefix units |
| Track Width | 355 mm |
| Track Pitch | 6.75 in (standard); 6.91 in (951C) |
Performance
| Travel Speed | 9.7 km/h |
| Transmission Types | Direct drive (on 72J and 78J prefix units); Powershift (on other prefixes) |
| Steering Type | Pedal steer (on 15H, 32F, 69H, 79H, and 86J prefixes) |
Blades
| Bucket Capacity | 1.15 m³ (1.5 yd³) |
| Standard Features | Automatic bucket positioner standard on specific serial ranges |
Service Capacities
| Engine Oil | 5.0 gal (for 951 series) |
| Transmission Oil | 10.0 gal (TO-4 30 weight) |
| Hydraulic Oil | 24.5 gal (TO-4 10W weight) |
| Coolant | 11.0 gal |
| Bevel Gear & Steering Clutches | 18.0 gal (Heavy Duty Diesel Engine Oil 10W-30) |
| Final Drives | 2.5 gal (Heavy Duty Diesel Engine Oil 20W-50) |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
951B fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine Crankcase (w/ filter) | 5.0 gal (18.93 L) | Heavy Duty Diesel Engine Oil 15W-40 (or 10W-30 for specific configurations/series) |
| Cooling System | 11.0 gal (41.64 L) | Not specified |
| Transmission/Powertrain (Powershift Transmission) | 10.0 gal (37.85 L) | Transmission Oil TO-4 30 |
| Bevel Gear/Steering Compartments | 18.0 gal (68.14 L) | Heavy Duty Diesel Engine Oil 10W-30 |
| Final Drives (each) | 2.5 gal (9.46 L) | Heavy Duty Diesel Engine Oil 20W-50 |
| Hydraulic System/Tank | 24.5 gal (92.74 L) | Transmission Oil TO-4 10W |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar 951B maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
Servicing the 951B beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize Caterpillar S.O.S fluid analysis to monitor the D330 engine oil and hydraulic systems. Regularly sample hydraulic oil to detect particle counts or oxidation levels that signal pump failure. Monitor coolant for pH changes or sodium presence, which indicates internal leaks. Analyzing transmission and final drive oil for wear metals like iron or copper allows for identifying gear or bushing degradation before catastrophic component failure occurs.
Corrective & Common Repairs
Address frequent hydraulic issues by inspecting hoses for abrasion and cylinders for seal leaks. The 951B may require replacement of bucket tooth pins or bushing kits due to high-impact loading. If the engine exhibits abnormal smoke, inspect the turbocharger and fuel system. For units with direct drive transmissions, monitor clutch engagement; powershift models require specific attention to steering clutch and brake component wear.
Overhaul & Rebuild Points
Plan major rebuilds around the 2,000-hour interval, focusing on a full hydraulic oil change and transmission service. Evaluate the engine for cylinder head or liner pitting if coolant analysis shows degradation. During structural overhauls, inspect boom welds and loader linkage for fatigue. Rebuilding final drives should include checking all bearings and gear surfaces for heavy pitting or excessive play in the drive assembly.
Seasonal & Environment Servicing
In dusty or quarry environments, check air filter restrictions daily and clean radiator fins to prevent overheating. For machines operating in cold climates, utilize appropriate engine oil weights and inspect battery condition for extreme temperature resilience. In high-moisture areas, prioritize the inspection of the sealed and lubricated track (SALT) components and ensure all pins and bushings are adequately greased to prevent corrosion.
951B common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 2P-7714 | Fuel Filter | Fuel system service | Check fitment → |
| 5S-9665 | Fuel Filter | Fuel system service | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
951B fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| 110-0 | Engine Coolant Temperature — Above Normal | Low coolant level, thermostat failure | Inspect cooling system, refill coolant, test thermostat |
| 110-3 | Engine Coolant Temp Sensor — Voltage High | Open circuit or sensor failure | Check wiring; replace sensor if confirmed faulty |
| 174-3 | Engine Fuel Temperature — Voltage Above Normal | Open circuit in sensor wiring | Inspect harness and replace sensor if necessary |
| 190-8 | Engine Speed — Abnormal Frequency | Speed sensor air gap, sensor failure, or tone ring damage | Check sensor gap; test speed sensor and tone ring |
| 41-3 | 8-Volt DC Supply — Voltage Above Normal | Short to power on 8V reference circuit | Inspect sensors sharing the 8V supply and isolate fault |
| 41-4 | 8-Volt DC Supply — Voltage Below Normal | Short to ground on 8V reference circuit | Disconnect sensors one at a time to locate short |
| 2348-9 | SAE J1939 Data Link #2 — Abnormal Update Rate | CAN bus wiring damage or termination fault | Check CAN wiring and measure termination resistance |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
951B attachments & work tools
Blades
Available blade types include S, SU, and A configurations. Specific widths or capacities for these blade types are not documented for the 951B.
Rippers
Ripper attachments are available for this model. Specific single-shank vs multi-shank options and weights are not specified in provided documentation.
Winches
Winch attachment availability is listed under general attachments, but specific class or towing capacity details for the 951B are not documented.
Cab/ROPS Guarding
The 951B features ROPS adaptability. Specific forestry or waste guarding options are not documented.
Hydraulic Arrangement
Angle cylinders and hydraulic kits for attachments are available. Recommended fluids include Cat HYDO Advanced, Cat DEO, and TDTO (TO-4).
All 951B assemblies by section
Every catalogued assembly group for the Caterpillar 951B. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Central Structure
5s6425 Balancer Group
| 5S***25 | Balancer Group; Balancer Group | 1 |
2p6201 Camshaft Group
| 2P***01 | Camshaft Group-Single; Single Camshaft Group | 1 |
5s6429 Connecting Rod And Piston Group
| 5S***29 | Connecting Rod And Piston; Connecting Rod And Piston Group | 1 |
Cylinder Block Cover (6a6610 N/S)
| 6A***10 | Cover Group-Cylinder Block; Cylinder Block Cover Group | 1 |
6a6610 Cylinder Block Cover Group
| 6A***10 | Cover Group-Cylinder Block; Cylinder Block Cover Group | 1 |
2p1686 Crankshaft Assembly--Field Installation
| 2P***86 | Crankshaft Assembly | 1 |
Crankshaft Bearing Replacement Groups
Crankshaft (2p6216 N/S)
| 2P***16 | Crankshaft Group | 1 |
6a6669 Cylinder Block Assembly
| 6A***69 | Cylinder Block As | 1 |
Cylinder Block Cover (6a6609 N/S)
| 6A***09 | Cylinder Block Cover | 1 |
6a6609 Cylinder Block Cover Group
| 6A***09 | Cylinder Block Cover | 1 |
6a3834 Cylinder Block Group
| 6A***34 | Cylinder Block Group; Cylinder Block Group | 1 |
4n4028 Connecting Rod And Piston Group
| 4N***28 | Piston & Rod Group; Connecting Rod And Piston Group | 1 |
9s8912 Connecting Rod And Piston Group
| 9S***12 | Piston & Rod Group; Connecting Rod And Piston Group | 1 |
2p6225 Crankshaft Seal Group
| 2P***25 | Seal Group-Crankshaft; Crankshaft Seal Group | 1 |
2p6223 Crankshaft Seal Group
| 2P***23 | Seal Group-Crankshaft; Crankshaft Seal Group | 1 |
Cooling System
2p6215 Engine Oil Cooler Group
| 2P***15 | Cooler Group-Engine Oil; Oil Cooler Group Engine | 1 |
2p6508 Transmission Oil Cooler Group
| 2P***08 | Cooler Group-Transmission Oil; Transmission Oil Cooler Group | 1 |
2p8165 Housing And Regulator Group
| 2P***65 | Housing & Regulator Group; Housing And Regulator Group | 1 |
3n3271 Housing And Regulator Group
| 3N***71 | Housing & Regulator Group; Housing And Regulator Group | 1 |
2p8164 Housing And Regulator Group
| 2P***64 | Housing & Regulator Group; Regulator And Housing Group | 1 |
2p8163 Housing And Regulator Group
| 2P***63 | Housing & Regulator Group; Housing And Regulator Group | 1 |
2p8169 Housing And Regulator Group
| 2P***69 | Housing & Regulator Group; Housing And Regulator Group | 1 |
2p8167 Housing And Regulator Group
| 2P***67 | Housing & Regulator Group; Regulator And Housing Group | 1 |
2p6188 Water Lines
| 2P***88 | Lines Group-Water; Water Lines Group | 1 |
2p7741 Water Pipe Lines Group
| 2P***41 | Lines Group-Water; Water Lines Group-- Pipe | 1 |
2p7740 Water Elbow Lines Group
| 2P***40 | Lines Group-Water; Water Lines Group--Elbow | 1 |
2p661 Water Pump
| 2P***61 | Pump Group-Water; Water Pump Group | 1 |
2p662 Water Pump
| 2P***62 | Pump Group-Water; Water Pump Group | 1 |
Engine Arrangement
5c785 Basic Engine Arrangement
| 2P***49 | Pipe Group-Exhaust; Exhaust Pipe Group | 0 |
| 2P***05 | Pulley Group; Pulley Group | 0 |
| 4N***79 | Exhaust Pipe Group | 0 |
5c790 Basic Engine Arrangement
| 2P***49 | Pipe Group-Exhaust; Exhaust Pipe Group | 0 |
| 2P***05 | Pulley Group; Pulley Group | 0 |
| 4N***79 | Exhaust Pipe Group | 1 |
Engine Arrangements
Front Structure
4n6508 Front Housing Cover Group
| 4N***08 | Cover Group-Front Housing; Front Housing Cover Group | 1 |
2p6529 Front Housing Cover Group
| 2P***29 | Cover Group-Front Housing; Front Housing Cover Group | 1 |
2p6528 Front Housing Cover Group
| 2P***28 | Cover Group-Front Housing; Front Housing Cover Group | 1 |
2p7831 Fan Drive Group
| 2P***31 | Drive Group-Fan; Fan Drive Group | 1 |
Fan Drive (4n8537 N/S)
| 4N***37 | Drive Group-Fan; Fan Drive Group | 1 |
6a7389 Fan Drive Group
| 6A***89 | Fan Drive Group | 1 |
Fan Drive (6a7389 N/S)
| 6A***89 | Fan Drive Group | 1 |
2p6498 Front Housing Fastener Group
| 2P***98 | Fastener Group-Front Housing; Front Housing Fastener Group | 1 |
2p6498 Front Housing Fasteners Group
| 2P***98 | Fastener Group-Front Housing; Front Housing Fastener Group | 1 |
2p6211 Front Gear Group--Timing
| 2P***11 | Front Gear Group; Front Gear Group-Timing | 1 |
2p6153 Front Housing Group
| 2P***53 | Front Housing; Front Housing Group | 1 |
2p9642 Front Gear Group--Timing
| 2P***42 | Gear Group-Front Timing | 1 |
2p9642 Front Timing Gear Group
| 2P***42 | Gear Group-Front Timing | 1 |
2p9641 Front Housing Group
| 2P***41 | Housing Group-Front; Front Housing Group | 1 |
2p8598 Crankshaft Hub Group
| 2P***98 | Hub Group-Crankshaft; Crankshaft Hub Group | 1 |
6a6620 Pulley Group
| 6A***20 | Pulley Group | 1 |
6a4274 Pulley Group
| 6A***74 | Pulley Group | 1 |
Pulley (2p8605 N/S)
| 2P***05 | Pulley Group; Pulley Group | 1 |
6a6621 Pulley Group
| 6A***21 | Pulley Group | 1 |
4n8281 Pulley Group--Type 1
| 4N***81 | Pulley Group; Pulley Group | 1 |
5c1987 Pulley Group
| 5C***87 | Pulley Group | 1 |
Pulley (6a5562 N/S)
| 6A***62 | Pulley Group | 1 |
Pulley (2p8610 N/S)
| 2P***10 | Pulley Group | 1 |
4n8281 Pulley Group--Type 2
| 4N***81 | Pulley Group; Pulley Group | 1 |
Pulley (4n3562 N/S)
| 4N***62 | Pulley Group-Crankshaft; Crankshaft Pulley Group | 1 |
5c2678 Support Group
| 5C***78 | Support Group | 1 |
2p7757 Support Group
| 2P***57 | Support Group | 1 |
4n5239 Support Group
| 4N***39 | Support Group-Engine; Engine Support Group | 1 |
2p7753 Support Group
| 2P***53 | Support Group-Engine; Front Engine Support Group | 1 |
2p7755 Support Group
| 2P***55 | Support Group-Engine | 1 |
2p6246 Trunnion Group
| 2P***46 | Trunnion Group-Engine | 1 |
Fuel System And Governor
9n867 Fuel Ratio Control Group
| 9N***67 | Control Group-Fuel Ratio | 1 |
6n2505 Torque Control Group
| 6N***05 | Control Group-Torque | 1 |
4n4510 Governor Cover Group
| 4N***10 | Cover Group-Governor; Governor Cover Group | 1 |
6n4413 Tachometer Drive Group
| 6N***13 | Drive Group-Tachometer; Tachometer Drive Group | 1 |
4n3303 Fuel Filter Group
| 4N***03 | Filter Group-Fuel; Fuel Filter Group | 1 |
2p975 Fuel Filter Group
| 2P***75 | Filter Group-Fuel; Fuel Filter Group | 1 |
Primary Fuel Filter (1p6835 N/S)
| 1P***35 | Filter Group-Primary Fuel; Primary Fuel Filter Group | 1 |
Fuel Filter (2p7714 N/S)
| 2P***14 | Fuel Filter | 1 |
5s9665 Fuel Filter Group
| 5S***65 | Fuel Filter | 1 |
Fuel Filter (5s9666 N/S)
| 5S***66 | Fuel Filter Group | 1 |
6n5916 Fuel Filter Group
| 6N***16 | Fuel Filter Group | 1 |
Fuel Injection Lines (2p7460 N/S)
| 2P***60 | Fuel Injection Lines | 1 |
Fuel Injection Lines (2p7461 N/S)
| 2P***61 | Fuel Injection Lines; Fuel Injection Lines Group | 1 |
6n728 Fuel Injection Lines Group
| 6N***28 | Fuel Injection Lines Group | 1 |
4n3374 Fuel Injection Lines Group
| 4N***74 | Fuel Injection Lines Group | 1 |
Fuel Injection Lines (6n727 N/S)
| 6N***27 | Fuel Injection Lines Group | 1 |
3n3387 Fuel Injection Pump Group
| 3N***87 | Fuel Injection Pump Group | 1 |
4n4882 Fuel Injection Lines Group--Part 1 Of 2
| 4N***82 | Fuel Injection Valves And Lines Group | 1 |
4n4882 Fuel Injection Lines Group--Part 2
| 4N***82 | Fuel Injection Valves And Lines Group | 1 |
4n4882 Fuel Injection Lines Group--Part 2 Of 2
| 4N***82 | Fuel Injection Valves And Lines Group | 1 |
5s2100 Fuel Priming Pump Group
| 5S***00 | Fuel Priming Pump | 1 |
Fuel Priming Pump (7s1251 N/S)
| 7S***51 | Fuel Priming Pump Group | 1 |
Fuel Priming Pump (2p7716 N/S)
| 2P***16 | Fuel Priming Pump Group | 1 |
Governor And Fuel Injection Pump (8s720 N/S)
| 8S***20 | Fuel Pump Housing And Governor; Governor And Fuel Injection Pump | 1 |
Governor And Fuel Injection Pump (7s5859 N/S)
| 7S***59 | Fuel Pump Housing And Governor | 1 |
Governor And Fuel Injection Pump (7s9334 N/S)
| 7S***34 | Fuel Pump Housing And Governor | 1 |
Governor And Fuel Injection Pump (8s727 N/S)
| 8S***27 | Fuel Pump Housing And Governor | 1 |
Governor And Fuel Injection Pump (8s728 N/S)
| 8S***28 | Fuel Pump Housing And Governor | 1 |
7s8831 Fuel Pump Housing Group
| 7S***31 | Fuel Pump Housing Group | 1 |
4n4900 Fuel Ratio Control Group
| 4N***00 | Fuel Ratio Control Group | 1 |
7s4430 Fuel Transfer Pump Group
| 7S***30 | Fuel Transfer Pump Group | 1 |
4n4873 Fuel Transfer Pump Group (7s5108 N/S)
| 4N***73 | Fuel Transfer Pump Group | 1 |
7s5445 Fuel Transfer Pump Group (7s5108 N/S)
| 7S***45 | Fuel Transfer Pump Group | 1 |
Glow Plug (5s8500 N/S)
| 5S***00 | Glow Plug Group; Glow Plug Group | 1 |
6n5356 Governor And Fuel Injection Pump Group--Part 3 Of 4
| 6N***56 | Gov & Fuel Inj Pump Group | 1 |
6n277 Governor And Fuel Injection Pump Group
| 6N***77 | Gov & Fuel Inj Pump Group; Governor And Fuel Injection Pump Group | 1 |
4n1834 Governor And Fuel Injection Pump Group--Part 2 Of 4
| 4N***34 | Gov & Fuel Inj Pump Group | 1 |
4n6115 Governor And Fuel Injection Pump Group
| 4N***15 | Gov & Fuel Inj Pump Group; Governor And Fuel Injection Pump Group | 1 |
6n284 Governor And Fuel Injection Pump Group--Replaced By 6n2476 Shown
| 6N***84 | Gov & Fuel Inj Pump Group | 1 |
4n1834 Governor And Fuel Injection Pump Group--Part 4 Of 4
| 4N***34 | Gov & Fuel Inj Pump Group | 1 |
6n281 Governor And Fuel Injection Pump Group
| 6N***81 | Gov & Fuel Inj Pump Group; Governor And Fuel Injection Pump Group | 1 |
6n243 Governor And Fuel Injection Pump Group
| 6N***43 | Gov & Fuel Inj Pump Group | 1 |
4n6116 Governor And Fuel Injection Pump Group--Field Installation
| 1P***36 | Gasket; (Fuel Priming Pump)(Fuel Priming Pump) | 1 |
| 1P***53 | Stop Bar .250" (6.35 mm) Thick | 1 |
| 2H***34 | Seal Transfer Pump To Plate | 1 |
6n247 Governor And Fuel Injection Pump Group--Type 1
| 6N***47 | Gov & Fuel Inj Pump Group | 1 |
4n1834 Governor And Fuel Injection Pump Group--Part 3 Of 4
| 4N***34 | Gov & Fuel Inj Pump Group | 1 |
6n5356 Governor And Fuel Injection Pump Group--Part 2 Of 4
| 6N***56 | Gov & Fuel Inj Pump Group | 1 |
6n5356 Governor And Fuel Injection Pump Group--Part 4 Of 4
| 6N***56 | Gov & Fuel Inj Pump Group | 1 |
4n1834 Governor And Fuel Injection Pump Group--Part 1 Of 4
| 4N***34 | Gov & Fuel Inj Pump Group | 1 |
6n5356 Governor And Fuel Injection Pump Group--Part 1 Of 4
| 6N***56 | Gov & Fuel Inj Pump Group | 1 |
6n279 Governor And Fuel Injection Pump Group
| 6N***79 | Gov & Fuel Inj Pump Group | 1 |
6n247 Governor And Fuel Injection Pump Group--Type 2
| 6N***47 | Gov & Fuel Inj Pump Group | 1 |
6n244 Governor And Fuel Injection Pump Group--Type 2
| 6N***44 | Governor And Fuel Injection Pump Group | 1 |
6n244 Governor And Fuel Injection Pump Group--Type 1
| 6N***44 | Governor And Fuel Injection Pump Group | 1 |
6n282 Governor And Fuel Injection Pump Group--Replaced By 6n2476 Shown
| 6N***82 | Governor And Fuel Injection Pump Group | 1 |
6n2477 Governor And Fuel Injection Pump Group
| 6N***77 | Governor And Fuel Injection Pump Group | 1 |
6n283 Governor And Fuel Injection Pump Group
| 6N***83 | Governor And Fuel Injection Pump Group | 1 |
6n282 Governor And Fuel Injection Pump Group
| 6N***82 | Governor And Fuel Injection Pump Group | 1 |
6n286 Governor And Fuel Injection Pump Group
| 6N***86 | Governor And Fuel Injection Pump Group | 1 |
Governor And Fuel Injection Pump Group (6n249 N/S)
| 6N***49 | Governor And Fuel Injection Pump Group | 1 |
6n2476 Governor And Fuel Injection Pump Group--Replaced By 4n6116
| 1P***36 | Gasket; (Fuel Priming Pump)(Fuel Priming Pump) | 1 |
| 1P***53 | Stop Bar .250" (6.35 mm) Thick | 1 |
| 2H***34 | Seal Transfer Pump To Plate | 1 |
6n275 Governor And Fuel Injection Pump Group--Replaced By 6n2476 Listed
| 6N***75 | Governor And Fuel Injection Pump Group | 1 |
6n274 Governor And Fuel Injection Pump Group--Replaced By 6n2476 Shown
| 6N***74 | Governor And Fuel Injection Pump Group | 1 |
7s9332 Governor Group--Part 1 Of 2--Type 1
| 7S***32 | Governor Group | 1 |
7s9333 Governor Group--Type 2
| 7S***33 | Governor Group | 1 |
7s9332 Governor Group--Part 2 Of 2--Type 1
| 7S***32 | Governor Group | 1 |
7s9333 Governor Group--Part 1 Of 2--Type 3
| 7S***33 | Governor Group | 1 |
7s9332 Governor Group--Part 1 Of 2--Type 2
| 7S***32 | Governor Group | 1 |
7s9332 Governor Group--Part 2 Of 2--Type 2
| 7S***32 | Governor Group | 1 |
7s9333 Governor Group--Part 2 Of 2--Type 3
| 7S***33 | Governor Group | 1 |
7s9333 Governor Group--Type 1
| 7S***33 | Governor Group | 1 |
Torque Control (8s6099 N/S)
| 8S***99 | Governor Torque Spring | 1 |
Torque Control (8s5549 N/S)
| 8S***49 | Governor Torque Spring | 1 |
Governor And Fuel Injection Pump (7s5858 N/S)
| 7S***58 | Injection Pump & Gov Group; Governor And Fuel Injection Pump Group | 1 |
9h2256 Fuel Priming Pump Assembly
| 9H***56 | Pump Assembly | 1 |
Fuel Priming Pump (4n4314 N/S)
| 4N***14 | Pump Group-Fuel Priming; Fuel Priming Pump Group | 1 |
4n3287 Fuel Priming Pump Group
| 4N***87 | Pump Group-Fuel Priming; Pump Group-Fuel Priming | 1 |
4n4864 Fuel Transfer Pump Group--Type 2
| 4N***64 | Pump Group-Fuel Transfer | 1 |
7s4429 Fuel Transfer Pump Group
| 7S***29 | Pump Group-Fuel Transfer; Fuel Transfer Pump Group | 1 |
4n4864 Fuel Transfer Pump Group--Type 1
| 4N***64 | Pump Group-Fuel Transfer | 1 |
Torque Control (9s3312 N/S)
| 9S***12 | Rack Stop Group | 1 |
Service Meter (9s8923 N/S)
| 9S***23 | Service Meter | 1 |
Service Meter (9s5141 N/S)
| 9S***41 | Service Meter | 1 |
Service Meter (9s7993 N/S)
| 9S***93 | Service Meter | 1 |
Service Meter Drive (2p6158 N/S)
| 2P***58 | Service Meter Drive | 1 |
Service Meter (2p6478 N/S)
| 2P***78 | Service Meter Group | 1 |
6n581 Torque Control Group
| 6N***81 | Torque Control Group | 1 |
Torque Control (6n509 N/S)
| 6N***09 | Torque Control Group | 1 |
Torque Control (9s3423 N/S)
| 9S***23 | Torque Spring Group | 1 |
Gasket Kits
Gasket Kits
| 5P***68 | Kit-Gasket; (Single Cylinder Liner)(Single Cylinder Liner) | 0 |
| 5P***71 | Water Pump- Serial No. 78p34523 To 78p40899 Inclusive | 0 |
| 5P***02 | 8n***60, 8n***61, 8n***15, 8n***16; 1w***78, 1w***79, 1w***86, 1w***87 | 0 |
Intake And Exhaust System
Accessory Drive (2p7712 N/S)
| 2P***12 | Accessory Drive | 1 |
Accessory Drive (2p7705 N/S)
| 2P***05 | Accessory Drive | 1 |
2p7794 Air Compressor Group
| 2P***94 | Air Compressor Group | 1 |
2p8711 Air Compressor Group
| 2P***11 | Air Compressor Group | 1 |
Air Compressor (2p8710 N/S)
| 2P***10 | Air Compressor Group; Air Compressor Group | 1 |
2p8709 Air Compressor Group
| 2P***09 | Air Compressor Group | 1 |
Air Compressor (2p8712 N/S)
| 2P***12 | Air Compressor Group; Air Compressor Group | 1 |
Air Compressor (2p7795 N/S)
| 2P***95 | Air Compressor Group; Air Compressor Group | 1 |
2p6837 Air Lines Group
| 2P***37 | Air Lines Group | 1 |
4n8279 Exhaust Pipe Group
| 4N***79 | Exhaust Pipe Group | 1 |
2p6533 Exhaust Manifold Fastener Group
| 2P***33 | Fastener Group-Exhaust Manifold; Exhaust Manifold Fastener Group | 1 |
4n9585 Exhaust Manifold Fastener Group
| 4N***85 | Fastener Group-Exhaust Manifold; Exhaust Manifold Fastener Group | 1 |
4n9584 Exhaust Manifold Fastener Group
| 4N***84 | Fastener Group-Exhaust Manifold; Exhaust Manifold Fastener Group | 1 |
Air Lines (2p6843 N/S)
| 2P***43 | Lines Group-Air; Air Lines Group | 1 |
Air Lines (6a7457 N/S)
| 6A***57 | Lines Group-Air; Air Lines Group | 1 |
4n4794 Air Lines Group
| 4N***94 | Lines Group-Air; Air Lines Group | 1 |
2p6840 Air Lines Group
| 2P***40 | Lines Group-Air; Air Lines Group | 1 |
6a7457 Air Lines Group
| 6A***57 | Lines Group-Air; Air Lines Group | 1 |
Air Lines (2p6839 N/S)
| 2P***39 | Lines Group-Air; Air Lines Group | 1 |
2p7796 Air Compressor Lines Group
| 2P***96 | Lines Group-Air Compressor; Air Compressor Lines Group | 1 |
4n3923 Turbocharger Oil Lines Group
| 4N***23 | Lines Group-Turbocharger Oil; Turbocharger Oil Lines Group | 1 |
4n3924 Turbocharger Oil Lines Group
| 4N***24 | Lines Group-Turbocharger Oil; Turbocharger Oil Lines Group | 1 |
Exhaust Manifold (2p6571 N/S)
| 2P***71 | Manifold Group-Exhaust; Exhaust Manifold Group | 1 |
Exhaust Manifold (2p6570 N/S)
| 2P***70 | Manifold Group-Exhaust; Exhaust Manifold Group | 1 |
4n8737 Exhaust Pipe Group
| 4N***37 | Pipe Group-Exhaust; Exhaust Pipe Group | 1 |
3p138 Exhaust Pipe Group
| 3P***38 | Pipe Group-Exhaust; Exhaust Pipe Group | 1 |
2p7349 Exhaust Pipe Group
| 2P***49 | Pipe Group-Exhaust; Exhaust Pipe Group | 1 |
1p9136 Turbocharger Group (1p9137 N/S)
| 1P***36 | Turbocharger Group | 1 |
4n6858 Turbocharger Group
| 4N***58 | Turbocharger Group | 1 |
4n6856 Turbocharger Group
| 4N***56 | Turbocharger Group; Turbocharger Group | 1 |
4n6859 Turbocharger Group
| 4N***59 | Turbocharger Group | 1 |
1p34 Turbocharger Group (1p8533 N/S)
| 1P***34 | Turbocharger Group | 1 |
4n6857 Turbocharger Group
| 4N***57 | Turbocharger Group; Turbocharger Group | 1 |
Turbocharger Oil Lines (2p7430 N/S)
| 2P***30 | Turbocharger Oil Lines Group | 1 |
Turbocharger Oil Lines (2p7353 N/S)
| 2P***53 | Turbocharger Oil Lines Group | 1 |
Lower Structure
2p6189 Oil Pan Fastener Group
| 2P***89 | Fastener Group-Oil Pan; Oil Pan Fastener Group | 1 |
2p6186 Oil Pan Fastener Group
| 2P***86 | Fastener Group-Oil Pan; Oil Pan Fastener Group | 1 |
2p990 Oil Level Gauge Group
| 2P***90 | Gauge Group-Oil Level (Dipstick) | 1 |
2p6494 Oil Level Gauge Group
| 2P***94 | Gauge Group-Oil Level (Dipstick); Oil Lever Gauge Group | 1 |
2p6491 Oil Level Gauge Group
| 2P***91 | Gauge Group-Oil Level (Dipstick) | 1 |
2p6175 Oil Pan Group
| 2P***75 | Pan Group-Oil; Pan Gp-Engine Oil | 1 |
Oil Pan (2p6155 N/S)
| 2P***55 | Pan Group-Oil; Oil Pan Group | 1 |
Lubrication System
Breather (1p4244 N/S)
| 1P***44 | Breather Group | 1 |
4n4817 Oil Filler Group
| 4N***17 | Filler Group-Oil; Oil Filler Group | 1 |
4n9821 Oil Filler Group
| 4N***21 | Filler Group-Oil; Oil Filler Group | 1 |
2p6855 Oil Filler Group
| 2P***55 | Filler Group-Oil | 1 |
2p6475 Oil Filter Group
| 2P***75 | Filter Group-Engine Oil; Oil Filter Group (10z1 ~ 10z7023) | 1 |
2p6525 Oil Filter Group
| 2P***25 | Filter Group-Oil | 1 |
Fumes Disposal (2p7446 N/S)
| 2P***46 | Fumes Disposal | 1 |
4n3325 Fumes Disposal Group
| 4N***25 | Fumes Disposal Group; Fumes Disposal Group | 1 |
3n3392 Fumes Disposal Group
| 3N***92 | Fumes Disposal Group; Fumes Disposal Group | 1 |
2p7447 Fumes Disposal Group
| 2P***47 | Fumes Disposal Group | 1 |
2p6512 Oil Lines Group
| 2P***12 | Lines Group-Engine Oil; Engine Oil Lines Group | 1 |
2p6513 Oil Lines Group
| 2P***13 | Lines Group-Engine Oil; Engine Oil Lines Group | 1 |
2p6857 Oil Filler Group
| 2P***57 | Oil Filler Group | 1 |
Oil Filler (2p6857 N/S)
| 2P***57 | Oil Filler Group | 1 |
2p1785 Oil Pump Group
| 2P***85 | Pump Group-Engine Oil | 1 |
2p1784 Oil Pump Group
| 2P***84 | Pump Group-Engine Oil; Engine Oil Pump Group | 1 |
Rear Structure
7s7753 Flywheel Group
| 7S***53 | Flywheel Group; Flywheel Group | 1 |
Flywheel (2p976 N/S)
| 2P***76 | Flywheel Group; Flywheel Group | 1 |
Flywheel (7s7877 N/S)
| 7S***77 | Flywheel Group; Flywheel Group | 1 |
Flywheel (7s7878 N/S)
| 7S***78 | Flywheel Group; Flywheel Group | 1 |
Flywheel Housing (5c3176 N/S)
| 5C***76 | Flywheel Housing | 1 |
5c3176 Flywheel Housing Group
| 5C***76 | Flywheel Housing | 1 |
2p6813 Flywheel Housing Group
| 2P***13 | Flywheel Housing Group | 1 |
5c3193 Flywheel Housing Group
| 5C***93 | Flywheel Housing Group | 1 |
2p6166 Flywheel Housing Group
| 2P***66 | Housing Group-Flywheel; Flywheel Housing Group | 1 |
Flywheel Housing (2p6166 N/S)
| 2P***66 | Housing Group-Flywheel; Flywheel Housing Group | 1 |
2p6119 Flywheel Housing Group--Type 2
| 2P***19 | Housing Group-Flywheel; Flywheel Housing Group | 1 |
2p6119 Flywheel Housing Group--Type 1
| 2P***19 | Housing Group-Flywheel; Flywheel Housing Group | 1 |
2p6119 Flywheel Housing Group
| 2P***19 | Housing Group-Flywheel; Flywheel Housing Group | 1 |
Upper Structure
Valve Mechanism Cover (2p6514 N/S)
| 2P***14 | Cover Group-Valve Mechanism; Valve Mechansim Cover Group | 1 |
4n7444 Cylinder Head Assembly
| 4N***44 | Cylinder Head Assembly | 1 |
2p6484 Cylinder Head Group
| 2P***84 | Cylinder Head Group; Cylinder Head Group | 1 |
2p6274 Cylinder Head Group
| 2P***74 | Cylinder Head Group; Cylinder Head Group | 1 |
Cylinder Head Fastener (2p6544 N/S)
| 2P***44 | Fastener Group-Cylinder Head; Cylinder Head Fastener Group | 1 |
1p3840 Lifting Eye Group
| 1P***40 | Lifting Group; Lifting Eye Group | 1 |
Valve Mechanism (2p6524 N/S)
| 2P***24 | Valve-Mechanism Group; Valve Mechanism Group | 1 |
951B serial number reference
Locate the machine ID plate on the outer frame of the equipment. The serial number prefix consists of the first three alphanumeric characters of the identification string.
| Prefix | Identifies | Notes |
|---|---|---|
| 15H | Japan | Powershift transmission and pedal steer. Production ended 1968. |
| 32F | Japan | 60-inch (152-cm) track gauge; powershift transmission and pedal steer. Beginning with S/N 32F00902, units received hydraulic track adjusters, automatic bucket positioner standard, and increased horsepower to 95 FWHP. |
| 69H | France | 60-inch (152-cm) track gauge; powershift transmission and pedal steer. Beginning with S/N 69H01833, units received sealed loader linkage. Beginning with S/N 69H03509, units received sleeve metering fuel system. Beginning with S/N 69H04330, units received sealed and lubricated track (SALT). |
| 72J | Japan | Direct drive transmission; production ended 1970. |
| 78J | Japan | Direct drive transmission; production ended 1968. |
| 79H | USA | Powershift transmission and pedal steer; production ended 1968. |
| 86J | USA | 60-inch (152-cm) track gauge; powershift transmission and pedal steer. Beginning with S/N 86J01992, units received hydraulic track adjusters, automatic bucket positioner standard, and increased horsepower to 95 FWHP. Beginning with S/N 86J02598, units received sleeve metering fuel system. Beginning with S/N 86J04520, units received sealed and lubricated track (SALT). Unit also received ROPS. |
Frequently asked questions
What engine is used in the Caterpillar 951B?
The 951B is powered by a four-cylinder Caterpillar D330 engine, producing 85 hp (63 kW) flywheel horsepower.
What is the standard operating weight of this loader?
The standard operating weight for the Caterpillar 951B is approximately 22,100 lb (10,000 kg).
What model replaced the 951B?
The Caterpillar 951B was succeeded by the 951C model in 1970.
What 951B owners discuss
What engine is typically installed in a Caterpillar 951B with serial number 86J00840?
This specific unit features the D330C engine. General 951B models may utilize the D330 or D330C engines depending on the exact serial range and configuration.
What are the known cooling system issues for the 951B series?
The 951B series is noted for a tendency to overheat during operation. For engine regulation, part of the OEM part reference is identified as the correct regulator. A functional thermostat should begin opening at 76.7°C (170°F) and reach a wide-open position of approximately 3/8 inch lift at 85°C (185°F).
What differences exist in the transmission between various 951B configurations?
Transmission type varies by serial number. Units with Japanese prefixes 72J and 78J are equipped with direct drive transmissions. All other 951B units utilize a powershift transmission with pedal steer capability.
What should be inspected regarding the undercarriage and track pitch when servicing a 951B?
The standard track pitch for many 951B units is 171.45 mm (6.75 inches). Users should check for worn sprocket profiles, specifically looking for low tooth height or elongated slots. Note that some later configurations transitioned to a 175.51 mm (6.91 inch) pitch. Rails are considered 100% worn when stretch reaches approximately 3.175 mm (0.125 inches) per pin.
What electrical component changes occurred during the production of this model?
During the machine's production lifespan, there was a documented transition from using generators to using alternators.
What should be checked when purchasing a used 951B?
Inspect the recoil spring assembly for damage. Check specifically for bent spring bolts, damaged pilots, or worn stops. If the hydraulic adjuster extension exceeds 203.2 mm (6-1/8 inches), there is an increased risk of recoil assembly failure.
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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