Caterpillar 966G II
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar 966G Series II is a medium wheel-type loader built from roughly 2001 to 2005, sitting between the original 966G and the later 966H in Caterpillar's 966 lineage. It replaces the first-generation 966G's 3126 engine with a Cat 3176C, a 10.3-liter (629 cu in) turbocharged, air-to-air aftercooled inline-six with ADEM III electronic control, rated at roughly 184 kW (246 hp) net flywheel power. Operating weight runs approximately 22.7 to 22.9 t (50,100 to 50,400 lb) depending on bucket, tire, and counterweight choice, with bucket capacities from 3.5 to 4.25 m3 (4.5 to 5.5 yd3). Cat offered it with standard-lift arrangements and a range of work tools for quarry, aggregate, and general construction loading, paired with a four-speed powershift transmission and an oscillating rear axle.
The Series II update over the original 966G centers on the engine and its electronics: the 3176C's ADEM III module manages fuel timing and injection pressure directly, stretches the engine oil change interval from 250 to 500 hours, and reports fault data to the cab monitor for faster diagnosis. Hydraulic and cooling system service points also moved to longer intervals, cutting owning and operating cost against the earlier 966G. Caterpillar phased the model out for the 966H around 2006, which moved to a C11 ACERT engine. Today the 966G II remains common in the used market as an affordable, well-supported mid-size loader; the 3176C shares its core design with other engines in the 3176 family, which keeps parts and rebuild kits comparatively easy to source even though the loader itself is out of production.
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 966G II specifications
Engine
| Engine model | Caterpillar 3176C with ATAAC (air-to-air aftercooled), direct injection, turbocharged, 4 valves per cylinder, ADEM III electronic control |
| Power | Net (flywheel) power 184 kW (246 hp) at 2150 rpm; maximum flywheel power 194 kW (260 hp); rated power per ISO 9249 and EEC 80/1269 is 193 kW (259 hp) |
| Displacement | 10.3 L (629 cu in); bore 125 mm (4.9 in), stroke 140 mm (5.5 in) |
| Cylinders | 6, in-line, direct injection |
| Peak torque | 1215 N.m (896 lb-ft) net at 1200 rpm; about 49% torque rise |
| Emissions tier | Meets US EPA Tier 2, EU Stage II, and Japan MOC requirements; no power derate required up to 3600 m (11,811 ft) altitude |
Weights
| Operating weight (standard) | 22 870 kg (50,400 lb) reference configuration with standard general purpose bucket |
| Operating weight (by configuration) | Ranges from about 22,660 kg to 23,440 kg (49,940 lb to 51,670 lb) depending on bucket type and ground engaging tool selection; includes sound suppressed ROPS/FOPS cab, standard 26.5 R25 XHA (L-3) tires, full fuel, coolant, lubricants and operator |
| Static tipping load, straight | About 16,080 kg to 18,560 kg (35,440 lb to 40,906 lb) depending on bucket and ground engaging tool configuration |
| Static tipping load, full 37 degree turn | About 14,120 kg to 16,430 kg (31,120 lb to 36,212 lb) depending on bucket and ground engaging tool configuration |
Dimensions
| Overall (transport) length | About 8775 mm to 9239 mm (28 ft 9 in to 30 ft 3 in), varies with bucket type and ground engaging tools |
| Overall width (tread/tires) | Tread width 2230 mm (7 ft 4 in) for all tire options; width over standard 26.5 R25 XHA (L-3) tires 2965 mm (117 in) |
| Overall height | Height to top of ROPS 3580 mm (11 ft 9 in); height to top of exhaust pipe 3535 mm (11 ft 7 in); height to top of hood 2555 mm (8 ft 5 in). Overall height with bucket at full raise runs about 5716 mm to 6162 mm (18 ft 9 in to 20 ft 2 in) depending on bucket type |
| Wheelbase | 3450 mm (11 ft 4 in) |
| Ground clearance | 471 mm (18.5 in) with standard 26.5 R25 XHA (L-3) tires; changes slightly with other tire options |
| Hinge pin (B-pin) height | 4225 mm (13 ft 10 in) at full raise; 485 mm (19 in) at carry position |
| Axle and frame clearance | Axle housing clearance 430 mm (1 ft 5 in); height to axle centerline 795 mm (2 ft 7 in) |
| Bucket linkage angles | Rack back at maximum lift 61 degrees, at carry 47 degrees, at ground 42 degrees; dump angle at maximum lift 50 degrees with a general purpose bucket (45 degrees with a material handling bucket) |
| Loader clearance circle | About 14,535 mm to 14,945 mm (47 ft 8 in to 49 ft 0 in) with bucket in carry position, depending on bucket type |
Performance
| Travel speeds, forward | 1st 7.2 kph (4.5 mph), 2nd 12.6 kph (7.8 mph), 3rd 21.7 kph (13.5 mph), 4th 37.2 kph (23.1 mph); rated with standard 26.5-R25 XHA L-3 tires |
| Travel speeds, reverse | 1st 8.2 kph (5.1 mph), 2nd 14.3 kph (8.9 mph), 3rd 24.6 kph (15.3 mph), 4th 38.5 kph (23.9 mph) |
| Breakout force | About 172.0 kN to 220.4 kN (38,633 lb to 49,515 lb) depending on bucket type and ground engaging tools, measured 102 mm (4 in) behind the cutting edge tip per SAE J732c |
| Steering | Hydraulic articulated-frame steering; full turn angle 37 degrees each direction, used as the basis for the articulated tipping-load rating |
| Hydraulic cycle times | Raise 6.9 seconds, dump 1.4 seconds, lower/empty/float-down 1.8 seconds; total cycle about 10.1 seconds |
Service capacities (summary)
| Fuel tank | 380 L (100.4 gal), standard tank |
| Hydraulic system | 207 L (55 gal) total including tank; hydraulic tank alone 140 L (37 gal) |
| Engine oil (crankcase) | 35 L (9 gal) |
| Cooling system | 80 L (21 gal) |
| Transmission | 50 L (13 gal) |
| Differentials and final drives | 64 L (17 gal) each, front and rear axle |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
966G II fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with filter) | 35 L (9.0 US gal) | Cat DEO or DEO-ULS multigrade diesel engine oil (meets Cat ECF-1-a/ECF-2/ECF-3, exceeds API CH-4). SAE 15W-40 covers -9.5°C to 50°C (15°F to 122°F); SAE 10W-30 covers -18°C to 40°C (0°F to 104°F). Colder climates use 5W-40, 5W-30, 0W-40, or 0W-30 down to -40°C (-40°F). Oil change interval extends to 500 hours (after an initial 250-hour service) with CH-4-grade oil. |
| Cooling system | 80 L (21.1 US gal) | Cat ELC (Extended Life Coolant), factory-filled as a 1:1 premix with water. Premix protects to -37°C (-34°F); ELC concentrate extends protection to -52°C (-62°F) for arctic duty. Minimum 30% glycol required on this air-to-air aftercooled engine to prevent water pump cavitation. Cat DEAC conventional coolant is an acceptable alternative but needs periodic supplemental coolant additive treatment. Coolant sight gauge is ground-level accessible. |
| Fuel tank | 380 L (100.4 US gal), standard | No. 2-D distillate diesel fuel meeting Cat's off-highway diesel fuel specification (comparable to ASTM D975 / EN 590); ultra-low-sulfur diesel acceptable. Winter-grade No. 1-D blends recommended in cold climates for better cold-flow properties. |
| Transmission (planetary powershift) | 50 L (13.2 US gal) | Cat TDTO (Transmission/Drive Train Oil), meets Cat TO-4 spec. SAE 30 covers 0°C to 43°C (32°F to 110°F); SAE 10W covers -20°C to 10°C (-4°F to 50°F); SAE 50 for warmer climates up to 50°C (122°F). Cat TDTO-TMS synthetic-blend multi-season oil spans a wider -20°C to 43°C (-4°F to 110°F) range in one grade. Ecology drain standard for spill-free service. |
| Final drive and differential - front | 64 L (16.9 US gal) | Cat TDTO, meets Cat TO-4 spec (same oil family as the transmission and rear axle). SAE 30 covers -20°C to 43°C (-4°F to 110°F); SAE 50 for 10°C to 50°C (50°F to 122°F); SAE 0W-20, 0W-30, or 5W-30 synthetic-blend grades for cold starts down to -40°C (-40°F). |
| Final drive and differential - rear | 64 L (16.9 US gal) | Same fluid as front axle: Cat TDTO meeting Cat TO-4 spec, viscosity selected by climate (SAE 0W-20/0W-30/5W-30 for cold starts, SAE 30 for moderate climates, SAE 50 for hot climates). Optional internal axle oil cooler and ecology drain available; limited-slip differential option requires standard TDTO, no separate additive. |
| Hydraulic system (including tank) | 207 L (54.7 US gal) | Cat HYDO Advanced 10 (SAE 10W) is the preferred hydraulic oil for -20°C to 40°C (-4°F to 104°F) ambient. Acceptable alternates: Cat HYDO, Cat MTO, Cat DEO/DEO-ULS, or Cat TDTO in a viscosity matched to climate (grades from SAE 0W-20 to SAE 15W-40 span -40°C to 50°C). A biodegradable oil meeting the Cat BF-1 spec can be used where required. Sight gauge and ecology drain standard. |
| Hydraulic tank | 140 L (37.0 US gal) | Same fluid as the hydraulic system: Cat HYDO Advanced 10 preferred, with Cat HYDO, MTO, DEO, or TDTO as viscosity-matched alternates. |
| Grease (all pin and bushing lube points) | Per lubrication schedule - no fixed refill volume | Cat Multipurpose Grease (NLGI 2, lithium-complex) for standard-duty pins and bushings; Cat Advanced 3Moly Grease (NLGI 2, 3% moly) for heavily loaded pin joints. Remote grease banks are located in the hitch area on the left side of the machine; an automated lubrication system is available as a factory option. U-joints are lifetime-lubricated. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar 966G II maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 50 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 4,000 h |
|
| Every 6,000 h |
|
Servicing the 966G II beyond the schedule
Predictive Maintenance & Fluid Analysis
Run S.O.S oil sampling on the 3176C engine, powershift transmission, hydraulic tank, and axle differentials on the intervals above; trending wear metals catches torque converter and final drive wear before it becomes a failure. Watch coolant for a fuel odor or a rising level, and check fuel for a milky look; both point to the 3176C's copper injector sleeve seals starting to leak between the fuel and cooling circuits. Track ADEM III fault codes at the cab monitor and log converter-stall temperature, since a hot torque converter housing signals cooler plugging or internal seal wear.
Corrective & Common Repairs
Injector sleeve seal failure is the signature 3176C repair on this loader: fuel leaking into coolant or coolant into fuel calls for pulling the sleeves and reworking the head, not just chasing a coolant loss. Transmission oil cooler plugging is the other recurring complaint; a plugged cooler overheats the transmission, cooks seals, and can take out the charging pump next. A loud milling or gritting noise from the transmission housing usually points to that pump failing. Inspect the torque converter housing regularly for oil accumulation, a sign of internal converter leakage.
Overhaul & Rebuild Points
Major overhaul targets on the 966G II are the Z-bar loader linkage pins and bushings, the lift and tilt cylinder rod seals, and the articulation and steering cylinder pins, all high-cycle wear points on a loader running daily bucket cycles. Torque converter and powershift transmission rebuilds tend to follow persistent overheating or pump failure rather than a fixed hour count. Front and rear differential and final drive planetaries warrant a teardown inspection once oil sampling shows rising metal content. Recheck ROPS/FOPS mounting hardware and structure at any major overhaul.
Seasonal & Environment Servicing
In cold climates, confirm extended-life coolant concentration before winter, fit a block heater, and switch to a winter-blend or treated diesel to prevent fuel gelling in the 3176C's fuel system. On hot, dusty aggregate or quarry sites, service the primary air filter more often than the base interval and clean the radiator and hydraulic oil cooler cores to keep the transmission and torque converter from running hot. Check tire inflation against ambient temperature swings, since the 26.5R25 tires lose pressure faster in cold weather and heat up faster loaded in summer.
966G II fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CID 0100 (Engine Oil Pressure Sensor) | Oil pressure sensor circuit reads out of normal range, or the sensor reports an actual low oil pressure event. | Damaged or corroded sensor connector, open/shorted sensor wiring, or genuinely low oil pressure from oil level, pump, or filter issues. | Check oil level first. Inspect the sensor connector and wiring for damage or corrosion, then verify sensor output with Cat ET before replacing the sensor. |
| CID 0110 (Engine Coolant Temperature Sensor) | Coolant temperature sensor circuit fault, or an actual high coolant temperature event. | Low coolant level, restricted radiator or fan drive fault, or a failed sensor/connector. | Check coolant level and radiator for debris, confirm fan drive operation, then check sensor wiring and connector before replacement. |
| CID 0253 (Personality Module Mismatch) | ADEM III ECM software/rating file does not match the engine's configured rating. | Incorrect flash file loaded during service, or an ECM swapped in from a differently rated engine. | Connect Cat ET, confirm the correct engine rating/personality file, and reflash with the correct file. |
| CID 0268 (Check Programmable Parameters) | ECM flags that customer or factory parameters need reconfirmation, usually after a service event. | ECM replaced or reflashed, or battery/ECM power interrupted before parameters were reconfirmed. | Connect Cat ET, review and reconfirm all customer and factory parameters, then clear the code. |
| CID 0273 (Turbo Outlet/Boost Pressure Sensor) | Boost pressure sensor signal circuit is open or shorted, reading outside the expected range. | Failed sensor, damaged sensor harness, or a corroded connector. | Inspect sensor wiring and connector, confirm sensor supply voltage, and replace the sensor if it fails a calibration check. |
| CID 0296 (Transmission ECM data link) | Engine ECM has lost data-link communication with the transmission ECM. | Damaged or corroded data-link wiring/connectors between the two ECMs, or the transmission ECM has lost power or ground. | Check data-link wiring and connectors, confirm transmission ECM power and ground, clear the code and retest with Cat ET. |
| CID 0320 (Crankshaft Position Sensor) | Crankshaft position signal is missing or erratic; engine may crank without starting or shut down while running. | Failed sensor, incorrect sensor air gap, debris on the sensor tip, or damaged wiring. | Check sensor air gap and mounting, inspect wiring and connector, test sensor resistance, and replace if out of specification. |
| CID 0342 (Camshaft Position Sensor) | Camshaft position signal is missing or erratic, affecting the engine's timing reference. | Failed sensor, damaged wiring, or a corroded connector. | Inspect the sensor and connector, verify wiring continuity, and replace the sensor if faulty. |
| CID 0562 (Caterpillar Monitoring System) | The Caterpillar Monitoring System module itself reports an internal fault. | Failing CMS display/gauge cluster module, or a wiring/power issue to the module. | Check CMS module power and ground connections, cycle key power, and replace the module if the fault persists after Cat ET diagnosis. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
966G II attachments & work tools
General purpose (GP) buckets
Pin-on or quick-coupler GP buckets for this class run roughly 3.5-5.5 m3 (4.6-7.2 yd3) heaped, with widths around 3.2 m (127 in), varying by edge/tooth configuration and dealer package. Accept bolt-on cutting edges, teeth, or teeth-and-segment combinations.
Material handling (MH) / high-tip buckets
Higher-discharge MH buckets are offered in the same size class for loading over truck sideboards or hoppers where extra dump clearance is needed. Capacity trades off against dump height and reach versus the GP bucket.
Rock and heavy-duty buckets
Reinforced rock buckets (standard and heavy-duty) are built for quarry and aggregate work where abrasion and impact loads are higher than general earthmoving. Typically run at or below GP bucket capacity for the added wear-life steel and reinforcement.
Ground engaging tools (GET)
Reversible bolt-on cutting edges are offered, with a heavy-duty option rated for meaningfully longer wear life than the standard edge. Bolt-on center and corner adapters, multiple tooth-tip profiles (wear life, penetration, strength), and heavy-duty reversible segments round out the GET line for this bucket class.
Pallet and construction forks
Factory or Cat Work Tools & Solutions (CWTS) pallet forks are sized for this loader class, with tine lengths and carriage widths scaled to the loader's lift-arm width. Used for palletized loads, bagged material, and general yard handling; mounts via the loader's quick coupler or a dedicated fork carriage.
Log, lumber, and millyard forks
Log/lumber forks and millyard forks are offered for forestry and sawmill handling. Typically paired with the forest machine hydraulic arrangement for the extra grapple/clamp function these tools need.
Woodchip, coal, and side-dump buckets
Lightweight high-capacity buckets (woodchip, coal, side-dump) are available for low-density bulk material where volume matters more than breakout force. These share the standard bucket mounting but are sized larger and built lighter than a rock or GP bucket of the same class.
Waste and industrial buckets
A dedicated waste bucket is offered for transfer-station, recycling, and demolition work, paired with the waste handling arrangement rather than used as a bolt-on option alone.
Plows and material handling arms
Snow/material plows and material handling arm attachments are listed among the specialty work tools for this size class, generally through CWTS rather than as a base-machine factory option.
Quick coupler
A hydraulic quick coupler is offered as a factory or dealer-installed option, giving a dedicated actuation circuit for fast tool changes between buckets and forks without pin work. Coupler-compatible buckets and forks are a distinct order option from pin-on tools.
High lift arrangement
The high lift linkage option adds roughly 0.56 m (22 in) of additional lift/dump height versus the standard linkage, using extended lift arms and a longer tilt cylinder. Trades some breakout force and cycle speed for reach, useful for loading over truck sideboards.
Forest machine arrangement
The forestry configuration adds a heavier-duty front frame, third-valve auxiliary hydraulics, a larger tilt cylinder, and extra counterweight for balance with grapple-type tools. Needed for log/millyard forks and other clamp-style forestry work tools that require a third hydraulic function.
Waste handling arrangement
The waste/industrial package adds the heavier front frame plus extensive guarding: axle seal guards, narrow steel fenders, light guards, a hinged power-train guard, front frame and hydraulic/fuel tank guards, steering cylinder guards, and a reinforced step ladder. Intended for transfer stations, scrap yards, recycling depots, and demolition sites; often specified with the waste bucket work tool.
Third valve / auxiliary hydraulics
A third hydraulic valve section is available beyond the standard raise/tilt circuit, needed for any work tool with an extra function (grapple close, clamp, rotate). Comes bundled with the forest and some specialty work-tool arrangements rather than as a universal standalone option.
All 966G II assemblies by section
Every catalogued assembly group for the Caterpillar 966G II. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Air Inlet And Exhaust System
222-1330 Lines Gp-Air -Custom
| 16***81 | Washer | 4 |
| 17***35 | U-Bolt; (M10x1.5-Thd) | 1 |
| 18***93 | Tube | 1 |
207-5086 Precleaner Gp
| 07***07 | Precleaner As; (Air Cleaner Turbine) | 1 |
| 1L***66 | Button (Plug) | 1 |
| 20***86 | Precleaner Group | 1 |
207-5090 Precleaner Gp
| 10***95 | Damper | 1 |
| 17***95 | Clamp | 2 |
| 1L***66 | Button (Plug) | 1 |
Braking System
220-2727 Accumulator Gp-Brake
| 06***35 | Valve-Gas | 1 |
| 11***10 | Protector-Gas Valve | 1 |
| 1J***71 | Seal (10.52 Degrees I.D.); Seal-O-Ring -- To Adapter | 1 |
220-2726 Accumulator Gp-Brake
| 06***35 | Valve-Gas | 1 |
| 11***10 | Protector-Gas Valve | 1 |
| 1J***71 | Seal (10.52 Degrees I.D.); Seal-O-Ring -- To Adapter | 1 |
232-4503 Control Gp-Service Brake -Custom
| 09***87 | Tee | 2 |
| 10***46 | Rod-Control | 1 |
| 10***03 | Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge) | 1 |
221-9454 Lines Gp-Service Brake -Custom
| 09***45 | Washer; (16.6x24x1.2-mm Thk) | 6 |
| 09***87 | Tee | 2 |
| 10***46 | Rod-Control | 1 |
106-1774 Valve Gp-Brake Control -Parking
| 10***74 | Valve Group-Brake Control; -Parking | 1 |
| 4J***33 | Seal Fuel Injection Pump | 2 |
| 9S***01 | Plug-O-Ring; (5/16-24 Thd) | 2 |
Cooling System
188-3090 Guard Gp-Fan
| 18***88 | Guard Assem. | 1 |
| 18***90 | Guard Group-Fan | 1 |
| 18***91 | Bracket Assem. | 6 |
220-1923 Radiator & Fan Gp -Custom
| 12***07 | Mount As-Resilient | 2 |
| 13***38 | Adapter | 1 |
| 16***76 | Bolt | 10 |
Electrical And Starting System
222-3346 Alternator Gp-Charging -Custom
| 18***94 | Alternator Group-Charging; -Waste Handling | 1 |
| 19***30 | Bracket As | 1 |
| 21***31 | Bracket | 1 |
3e-7577 Alternator Gp-Charging
| 10***31 | Fan-Alternator; (11-Blade) | 1 |
| 10***32 | Collar; (Alternator) | 1 |
| 10***56 | Diode As; (Alternator) | 1 |
9w-0742 Block Gp-Junction
| 6V***22 | Tube-Heat Shrink; (25.4-mm Dia)(10-M) | 0 |
| 7F***60 | Washer | 6 |
| 8C***58 | Block Group-Junction; (Battery) | 1 |
231-3992 Panel Gp-Circuit Breaker -Custom
| 16***79 | Bolt | 4 |
| 18***90 | Panel Group-Circuit Breaker | 1 |
| 22***62 | Washer | 4 |
231-4415 Panel Gp-Circuit Breaker -Custom
| 0S***70 | Cap Screw (5/8" Long) | 2 |
| 10***01 | Kit; (Receptacle) (12-Pin) (Includes Receptacle As & Wedge) | 1 |
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 6 |
193-2550 Sensor Gp-Speed
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 17***49 | Strap; (Marker) | 1 |
| 19***50 | Sensor Group-Speed; -Tmsn, Torque Converter Output | 1 |
118-7226 Sensor Gp-Temperature
| 10***03 | Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge) | 1 |
| 11***26 | Sensor Group-Temperature; -Transmission Oil | 1 |
| 3E***71 | Wedge; (Receptacle Lock) (3 Pin) | 1 |
231-8562 Switch Gp-Disconnect -Custom
| 18***88 | Bolt | 2 |
| 18***89 | Washer; (6.4x12.5x1.6-mm Thk) | 4 |
| 19***63 | Nut; (M6x1-Thd) | 2 |
167-0138 Switch Gp-Magnetic
| 15***70 | Kit-Connecting Plug; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 16***38 | Switch Group-Magnetic; -Main Relay-Main Power Relay | 1 |
| 3E***62 | Wedge-Plug Lock; (2-Pin) | 1 |
125-1302 Switch Gp-Magnetic
| 01***80 | Lockwasher | 2 |
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 12***02 | Switch Group-Magnetic; -Starting Motor, Start Relay | 1 |
197-4147 Switch Gp-Ride Control
| 10***33 | Switch As-Rocker; (Ride Control) | 1 |
| 19***47 | Switch Group-Ride Control; (Ride Control) | 1 |
| 3E***80 | Actuator-Rocker | 1 |
197-6476 Switch Gp-Secondary Steering
| 14***01 | Switch As-Rocker; (Secondary Steering Test) | 1 |
| 14***02 | Actuator-Rocker | 1 |
| 14***03 | Switch As-Rocker; (Secondary Steering Test) | 1 |
197-6888 Wiring Gp-Air Conditioner
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 11***33 | Switch As-Pressure; (A/C) | 1 |
| 18***35 | Pin-Connector; (16-Ga To 18-Ga) | 2 |
135-6782 Wiring Gp-Ride Control
| 13***00 | Clip; (Tab) | 1 |
| 13***01 | Clip | 1 |
| 13***82 | Wiring Group-Ride Control; (Ride Control) | 1 |
184-7259 Wiring Gp-Secondary Steering
| 03***48 | Clip; (11.11mm .437in Id) | 2 |
| 10***03 | Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge) | 1 |
| 10***05 | Kit-Receptacle; (6-Pin)(Display Monitor Harness) | 1 |
Frame And Body
195-9833 Pin Gp-Hood -Custom
| 12***30 | Pin Assem. (R. H.) | 1 |
| 12***31 | Pin Assem. (L. H.) | 1 |
| 19***21 | Pin As; (Rh) | 1 |
205-4512 Protection Ar-Hardware -Custom
| 14***35 | Bolt | 2 |
| 14***36 | Bolt | 11 |
| 16***76 | Bolt | 6 |
Hydraulic System
221-1758 Accumulator Gp-Ride Control
| 11***10 | Protector-Gas Valve | 1 |
| 17***94 | Kit-Seal; (Ride Control Accumulator) | 0 |
| 1J***71 | Seal (10.52 Degrees I.D.); Seal-O-Ring -- To Adapter | 1 |
223-2264 Control Ar-Ride -Custom
| 13***97 | Bracket | 1 |
| 13***57 | Tube Assem. | 1 |
| 14***25 | Bracket | 1 |
231-8596 Control Gp-Ride -Custom
| 13***82 | Wiring Group-Ride Control; (Ride Control) | 1 |
| 14***03 | Valve & Mtg Group-Main Control; -2-Function | 1 |
| 14***56 | Lines Group-Pilot | 1 |
231-8597 Lines Gp-Front -Custom
| 13***66 | Tube As | 1 |
| 13***67 | Tube As | 1 |
| 13***68 | Tube As | 1 |
232-3110 Lines Gp-Pilot -Custom
| 14***36 | Bolt | 1 |
| 16***75 | Bolt | 2 |
| 19***63 | Washer | 3 |
222-1489 Lines Gp-Ride Control
| 13***97 | Bracket | 1 |
| 13***26 | Hose Assem. | 1 |
| 13***57 | Tube Assem. | 1 |
161-8919 Motor Gp-Piston -Hydraulic Fan
| 03***81 | Bearing As-Needle | 1 |
| 11***34 | Plug-O-Ring; (9/16-18 Thd) | 1 |
| 11***35 | Seal-Shaft | 1 |
232-0680 Valve & Mtg Gp-Main Control -Custom
| 13***62 | Bracket Assem. | 1 |
| 13***60 | Tube Assem. | 1 |
| 13***73 | Manifold | 1 |
232-0677 Valve & Mtg Gp-Main Control -Custom
| 23***77 | Valve & Mtg Group-Main Control; -Custom | 1 |
| 23***80 | Valve & Mtg Group-Main Control; -Custom | 1 |
| 7X***15 | Washer-Hard; (17x35x5-mm Thk) | 2 |
239-6776 Valve & Mtg Gp-Main Control -Custom
| 13***62 | Bracket Assem. | 1 |
| 13***59 | Tube Assem. | 1 |
| 13***73 | Manifold | 1 |
239-6778 Valve & Mtg Gp-Main Control -Custom
| 23***76 | Valve & Mtg Group-Main Control; -Custom | 1 |
| 23***78 | Valve & Mtg Group-Main Control; -Custom | 1 |
| 7X***15 | Washer-Hard; (17x35x5-mm Thk) | 2 |
118-5095 Valve Gp-Control -Auxiliary
| 09***91 | Bolt; (Locking) (M12x1.75x25mm) | 1 |
| 11***95 | Valve Group; (Auxiliary)(Auxiliary) | 1 |
| 16***06 | Spring; (Outer) | 1 |
9t-3096 Valve Gp-Check -Ride Control
| 20***02 | Valve Group-Check; (Park Brake Release) | 1 |
| 20***34 | Valve Group-Check; (Park Brake Release) | 1 |
| 3J***07 | Seal Valve Assembly To; Seal- Tube Assembly To Logic Valve | 1 |
223-5975 Valve Gp-Diverter -Ride Control
| 15***40 | Valve Group-Solenoid; -Reversing Fan, Ride Control | 2 |
| 1S***42 | Spring | 1 |
| 20***37 | Retainer | 3 |
232-2292 Valve Gp-Main Control
| 00***63 | Seal-O-Ring; (55.24mm Id) | 3 |
| 09***91 | Bolt; (Locking) (M12x1.75x25mm) | 2 |
| 11***88 | Valve Group-Main Control | 1 |
114-2788 Valve Gp-Main Control
| 00***63 | Seal-O-Ring; (55.24mm Id) | 3 |
| 09***91 | Bolt; (Locking) (M12x1.75x25mm) | 2 |
| 11***88 | Valve Group-Main Control | 1 |
239-6775 Valve Gp-Main Control
| 00***63 | Seal-O-Ring; (55.24mm Id) | 2 |
| 09***91 | Bolt; (Locking) (M12x1.75x25mm) | 2 |
| 11***88 | Valve Group-Main Control | 1 |
144-0115 Valve Gp-Pilot -Oil Manifold
| 11***68 | Valve Group-Sequence; -Float | 1 |
| 14***15 | Valve Group-Pilot; -Oil Manifold | 1 |
| 15***91 | Valve Group-Pressure Reducing; -Lowering Control | 1 |
154-8871 Valve Gp-Pressure Reducing
| 15***71 | Valve Group-Pressure Reducing; -Lowering Control | 1 |
| 2M***80 | Seal--To Connector Pump Outlet | 1 |
| 5P***99 | Ring-To Clutch Piston Pins | 1 |
154-0191 Valve Gp-Pressure Reducing
| 15***91 | Valve Group-Pressure Reducing; -Lowering Control | 1 |
| 2M***80 | Seal--To Connector Pump Outlet | 1 |
| 5P***99 | Ring-To Clutch Piston Pins | 1 |
4t-4935 Valve Gp-Relief
| 3K***60 | Seal Pilot Manifold On; Seal To Boom Check Valve Drain | 2 |
| 4T***35 | Valve Group-Relief; -Main-Implement Inlet Manifiold | 1 |
| 4T***42 | Spring | 1 |
4t-6103 Valve Gp-Relief
| 3K***60 | Seal Pilot Manifold On; Seal To Boom Check Valve Drain | 2 |
| 4T***41 | Spring | 1 |
| 4T***03 | Valve Group-Relief; (Line, Tilt Cyl Rod End Port) | 1 |
114-2789 Valve Gp-Relief
| 11***89 | Valve Group-Relief | 1 |
| 3K***60 | Seal Pilot Manifold On; Seal To Boom Check Valve Drain | 1 |
| 4J***22 | Seal-Interface Between 3rd & Tilt Valve | 1 |
4t-4162 Valve Gp-Relief -Line
| 3K***60 | Seal Pilot Manifold On; Seal To Boom Check Valve Drain | 2 |
| 4T***41 | Spring | 1 |
| 4T***62 | Valve Group-Relief; (Line, Auxiliary Cyl Rod End) | 1 |
6e-6003 Valve Gp-Relief -Main
| 11***15 | Dowel | 1 |
| 3K***60 | Seal Pilot Manifold On; Seal To Boom Check Valve Drain | 1 |
| 4J***22 | Seal-Interface Between 3rd & Tilt Valve | 1 |
4t-2742 Valve Gp-Relief -Line
| 3K***60 | Seal Pilot Manifold On; Seal To Boom Check Valve Drain | 2 |
| 4T***41 | Spring | 1 |
| 4T***42 | Valve Group-Relief; -Secondary Steering | 1 |
6e-2377 Valve Gp-Relief -Line
| 3K***60 | Seal Pilot Manifold On; Seal To Boom Check Valve Drain | 2 |
| 4T***41 | Spring | 1 |
| 4T***71 | Plate | 1 |
4t-4934 Valve Gp-Relief
| 3K***60 | Seal Pilot Manifold On; Seal To Boom Check Valve Drain | 2 |
| 4T***41 | Spring | 1 |
| 4T***34 | Valve Group-Relief; -Brake Accumulator Pressure | 1 |
114-1268 Valve Gp-Sequence
| 11***68 | Valve Group-Sequence; -Float | 1 |
| 2M***80 | Seal--To Connector Pump Outlet | 1 |
| 5P***99 | Ring-To Clutch Piston Pins | 1 |
4t-1860 Valve Gp-Shuttle
| 1M***18 | Ball | 1 |
| 3J***07 | Seal Valve Assembly To; Seal- Tube Assembly To Logic Valve | 1 |
| 4T***60 | Valve Group-Shuttle; -Ripper Lift-Ripper Tilt-Blade Tilt-Blade Lift | 1 |
6e-3373 Valve Gp-Shuttle
| 2M***80 | Seal--To Connector Pump Outlet | 1 |
| 5P***99 | Ring-To Clutch Piston Pins | 1 |
| 6E***10 | Seal-O-Ring; (16.10mm Id) | 1 |
152-8340 Valve Gp-Solenoid
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 11***43 | Locknut; (5/16-18-Thd) | 2 |
| 15***38 | Cartridge Assem. | 1 |
Machine Arrangement
195-1877 Conversion Gp-Machine -Custom
| 10***96 | Pin-Keeper | 1 |
| 11***55 | Pin Assem. | 1 |
| 11***91 | Bracket Assem. | 2 |
205-4502 Protection Ar-Corrosion -Custom
| 18***17 | Transmission Ar; -Freewheel Stator Torque Converter | 1 |
| 18***66 | Radiator & Fan Group | 1 |
| 19***67 | Plate & Film Group; -Custom | 1 |
232-1475 Protection Ar-Corrosion -Custom
| 18***15 | Transmission Ar; -Freewheel Stator Torque Converter | 1 |
| 18***66 | Radiator & Fan Group | 1 |
| 19***67 | Plate & Film Group; -Custom | 1 |
Operator Station
223-2269 Air Conditioner Ar -Custom
| 11***93 | Plate; (Instruction) (On Right Side Behind Cab Door) | 1 |
| 18***21 | Air Conditioner Ar | 1 |
| 19***88 | Wiring Group-Air Conditioner | 1 |
200-7503 Air Conditioner Gp -Custom
| 18***93 | Heater Group-Cab | 1 |
| 19***21 | Lines Group-Air Conditioner | 1 |
| 20***03 | Air Conditioner Group; -Custom | 1 |
220-4169 Lines Gp-Air Conditioner
| 10***00 | Fitting As-Air Conditioner; (Quick Disconnect)(Refrigerant) | 2 |
| 10***81 | Clamp Assem. | 1 |
| 10***97 | Valve As; (Low Side) | 1 |
232-7683 Lines Gp-Air Conditioner -Custom
| 10***81 | Clamp Assem. | 1 |
| 1P***56 | Plate | 1 |
| 20***02 | Clamp As | 1 |
193-3121 Lines Gp-Air Conditioner
| 10***93 | Valve As | 1 |
| 10***94 | Gasket | 1 |
| 10***95 | Valve As | 1 |
Power Train
116-6128 Case & Parts Gp-Planetary
| 11***94 | Tube Assem. | 1 |
| 11***28 | Case & Parts Group-Planetary | 1 |
| 12***23 | Bracket Assem. | 1 |
199-3323 Control Gp-Transmission Hyd
| 06***40 | Seal-O-Ring (Id=37.69mm) | 1 |
| 11***26 | Sensor Group-Temperature; -Transmission Oil | 1 |
| 13***00 | Clip; (Tab) | 2 |
223-4459 Gear Gp-Output Transfer
| 11***31 | Cage-Bearing | 1 |
| 11***65 | Yoke Assem. | 2 |
| 12***28 | Cage Assem. | 1 |
196-1800 Planetary Gp-Transmission
| 06***11 | Ring-Retaining | 1 |
| 06***61 | Ring-Retaining | 1 |
| 06***93 | Ring-Retaining | 1 |
196-1799 Planetary Gp-Transmission
| 06***11 | Ring-Retaining | 1 |
| 06***61 | Ring-Retaining | 1 |
| 06***93 | Ring-Retaining | 1 |
124-6662 Pump Gp-Transmission
| 12***12 | Manifold Assem. | 1 |
| 12***62 | Pump Group-Transmission | 1 |
| 12***94 | Cover As-Oil Pump | 1 |
183-7432 Torque Converter & Housing Gp
| 0S***79 | Bolt 5.08 cm(2 In.) Long | 1 |
| 0S***90 | Bolt; (3/8-16x2in)(Clip Thru Spacer To Bracket As) | 8 |
| 12***79 | Flange-Pump Drive | 1 |
177-7083 Torque Converter Gp
| 06***43 | Ring-Snap | 1 |
| 11***27 | Ball Bearing | 1 |
| 14***21 | Gear-Pump Drive; (67-Teeth) | 1 |
233-7333 Transmission Ar -Custom
| 15***40 | Grease-Dielectric | 1 |
| 18***17 | Transmission Ar; -Freewheel Stator Torque Converter | 1 |
| 23***33 | Transmission Ar; -Custom | 1 |
180-9115 Transmission Ar
| 11***28 | Case & Parts Group-Planetary | 1 |
| 12***62 | Pump Group-Transmission | 1 |
| 14***68 | Gear Group-Output Transfer | 1 |
233-7334 Transmission Ar -Custom
| 13***09 | Tube-Heat Shrink; (32-mm Dia)(16-cm) | 0 |
| 13***10 | Tube; (12-cm) | 0 |
| 15***40 | Grease-Dielectric | 1 |
180-9117 Transmission Ar
| 11***28 | Case & Parts Group-Planetary | 1 |
| 12***62 | Pump Group-Transmission | 1 |
| 18***17 | Transmission Ar; -Freewheel Stator Torque Converter | 1 |
160-8408 Valve Gp-Modulating -Transmission Clutch
| 14***44 | Coil Assem. | 1 |
| 16***08 | Valve Group-Modulating; -Torque Converter Lockup Clutch | 1 |
| 16***08 | Washer; (13.03x25.4x2.38-mm Thk) | 1 |
202-8933 Valve Gp-Relief -Transmission Hydraulic Control
| 11***00 | Body | 1 |
| 1M***51 | Spring-Steering Clutch | 1 |
| 20***05 | Cover | 1 |
130-5485 Valve Gp-Relief -Torque Converter Outlet
| 13***85 | Valve Group-Relief; -Torque Converter Outlet | 1 |
| 2S***82 | Spring | 1 |
| 2S***84 | Spool Assembly, Comprising: | 1 |
Service Equipment And Supplies
195-1875 Cover Gp-Protection -Custom
| 19***71 | Lever | 1 |
| 19***72 | Cover | 1 |
| 19***73 | Cap As-Filler | 1 |
194-7867 Plate & Film Gp -Custom
| 13***59 | Plate-Identification; (Engine Stop, Run) | 0 |
| 18***52 | Plate-Hood; (Hood) | 1 |
| 19***67 | Plate & Film Group; -Custom | 1 |
Steering System
223-2266 Conversion Ar-Secondary Steer -Custom
| 14***43 | Tube Assem. | 1 |
| 14***55 | Bracket | 1 |
| 14***34 | Bracket | 1 |
146-1547 Lines Gp-Secondary Steering
| 14***97 | Valve Group-Secondary Steering | 1 |
| 14***14 | Flange | 1 |
| 14***36 | Hose Assem. | 1 |
177-2921 Pump & Motor Gp-Sec Steering
| 11***68 | Gasket | 1 |
| 17***21 | Pump & Motor Group-Sec Steering | 1 |
| 18***65 | Kit-Service; (Secondary Steering Pump) | 1 |
237-9875 Pump & Motor Gp-Sec Steering
| 11***68 | Gasket | 1 |
| 18***67 | Motor Group-Electric; (Secondary Steering) | 1 |
| 18***70 | Relay; (Secondary Steering Motor), Washer, Washer; Din 7989 | 1 |
234-4892 Pump & Motor Gp-Sec Steering -Custom
| 10***05 | Kit-Receptacle; (6-Pin)(Display Monitor Harness) | 1 |
| 15***69 | Plug As-Connector; (2-Pin) | 1 |
| 18***61 | Harness Assembly-Secondary Steering | 1 |
146-1553 Pump & Mtg Gp-Secondary Steer
| 14***53 | Pump & Mtg Group-Secondary Steer | 1 |
| 14***55 | Bracket | 1 |
| 14***34 | Bracket | 1 |
231-8595 Steering Gp-Secondary -Custom
| 14***47 | Lines Group-Secondary Steering | 1 |
| 14***53 | Pump & Mtg Group-Secondary Steer | 1 |
| 18***59 | Wiring Group-Secondary Steering; (Secondary Steering) | 1 |
141-2597 Valve Gp-Secondary Steering
| 10***10 | Valve-Check; (Steering) | 2 |
| 10***11 | Plug; (5/16-12 Thd) | 2 |
| 14***97 | Valve Group-Secondary Steering | 1 |
966G II serial number reference
The PIN plate is on the left side of the loader frame, ahead of the cab near the articulation joint, on this generation of Cat wheel loader. The plate reads as an 8-character PIN: a 3-letter prefix identifying the model/build lot, followed by a 5-digit sequence number showing build order within that prefix (example: AWY00001). Match the 3-letter prefix against the model's parts or service manual machine-models section to pin down the exact configuration and engine arrangement, since these prefixes split across a running engine change from the 3176 to the 3176C (ATAAC) arrangement over the production run.
| Prefix | Identifies | Notes |
|---|---|---|
| AWY | 966G Series II | Base/early production PIN prefix for the 966G Series II. Parts references show this prefix powered by the Cat 3176 turbocharged diesel (pre-ATAAC arrangement). |
| ANT | 966G Series II | 966G Series II production prefix. Parts references show this prefix powered by the Cat 3176C turbocharged diesel with air-to-air aftercooling (ATAAC). |
| AXJ | 966G Series II | 966G Series II production prefix. Parts references show this prefix powered by the Cat 3176 turbocharged diesel (pre-ATAAC arrangement). Also covers a High Lift/logging linkage and hydraulic valve option package specific to this prefix. |
| AXL | 966G Series II | 966G Series II production prefix. Parts references show this prefix powered by the Cat 3176C turbocharged diesel with ATAAC. |
| ANZ | 966G Series II | 966G Series II production prefix. Parts references show this prefix powered by the Cat 3176C turbocharged diesel with ATAAC. |
| AWZ | 966G Series II | 966G Series II production prefix. Parts references show this prefix powered by the Cat 3176C turbocharged diesel with ATAAC, and this prefix is tied to a Command Control Steering (joystick steer) option package. |
Frequently asked questions
What engine does the Caterpillar 966G II use?
The 966G Series II runs a Caterpillar 3176C, a 10.3-liter (629 cu in) turbocharged, air-to-air aftercooled inline-six with ADEM III electronic control, rated at roughly 184 kW (246 hp) net flywheel power. This replaced the original 966G's mechanically governed 3126 engine.
What is the operating weight of the Caterpillar 966G II?
Operating weight runs approximately 22.7 to 22.9 t (50,100 to 50,400 lb), depending on bucket, tire, and counterweight configuration.
What replaced the Caterpillar 966G II?
Caterpillar replaced the 966G Series II with the 966H around 2006, which moved to a C11 ACERT engine rated near 195 kW (262 hp) net.
What 966G II owners discuss
What engine is actually in the 966G II, and is it the same as the earlier 966G?
Is the transmission overheating complaint on this platform a real pattern, or a one-off?
What does weak or slow bucket lift usually point to on this loader?
What wears fastest on a machine like this, since it doesn't have a track undercarriage?
A used 966G II keeps throwing a low oil pressure alarm even after an engine rebuild — what's going on?
The joystick feels lazy or inconsistent after a control valve swap — is there an adjustment for that?
What should I check before buying a used 966G II?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific 966G II part?
Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.