Caterpillarwheel-type loaderwheel loader
Caterpillar 990 II
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar 990 II is a large wheel loader built for quarry, aggregate, and bulk-material loading, sized to match 50- to 70-ton off-highway haulers. It was produced from 1996 to 2005, replacing the original mechanically-injected 990 and carrying the platform to a Cat 3412E TA V-12 diesel with HEUI electronic unit injection, ADEM III engine controls, air-to-air aftercooling, and Tier 2 emissions compliance. Gross power is rated around 503 kW (675 hp), with flywheel/net output near 466 kW (625 hp). Standard-configuration operating weight runs about 73.5 t (162,000 lb); High Lift and quarry-duty configurations with larger buckets push closer to 83 t (183,500 lb). Bucket capacity spans roughly 8.4 to 9.2 m3 (11.0 to 12.0 yd3) heaped, depending on the bucket fitted. Caterpillar carried the platform forward as the 990H, powered by the C27 ACERT engine.
The Series II update moved this loader off the original 990's mechanical fuel system and onto electronically controlled HEUI injection, improving fuel control, cold-start behavior, and emissions compliance without changing the proven 3412 V-12 block underneath. Power class, the three-speed powershift transmission with lockup torque converter, and the articulated chassis carried over largely unchanged from the earlier 990, so the Series II reads as a controls and emissions revision rather than a clean-sheet redesign. In the used and parts market the 990 II remains a common working loader in quarries, mines, and bulk-handling yards, valued for the rebuildable 3412E block, parts commonality with other 3412E-powered Cat machines, and a large installed base that keeps used units, salvage components, and rebuild kits in steady supply even as Caterpillar's newer 990H and 990K generations have taken over new-equipment sales.
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 990 II specifications
Engine
| Engine model | Cat 3412E TA V-12 diesel, turbocharged with air-to-air aftercooling (DITA/ATAAC); ADEM III electronic control with HEUI fuel system |
| Gross power | 503 kW (675 hp) |
| Net/flywheel power | 462-466 kW (620-625 hp) at 2,000 rpm; figure varies slightly by rating standard (SAE J1349 approx. 618 hp, ISO 9249/EEC 80/1269 approx. 625 hp, DIN 70020 approx. 648 PS) |
| Displacement | 27.0 L (1,647.7 cu in) |
| Bore x stroke | 137.2 mm x 152.4 mm (5.4 in x 6.0 in) |
| Cylinders | 12, V-configuration |
| Emissions | Described in Cat product literature as meeting US EPA Tier 2 / EU Stage II requirements |
Weights
| Operating weight, standard arrangement | 73,490-76,500 kg (162,018-168,700 lb) - figure varies by source and by tire/bucket configuration |
| Operating weight, High Lift arrangement | approx. 83,246 kg (183,539 lb) |
| Rated payload | 15 t (33,000 lb) |
| Static tipping load, straight, standard arrangement | approx. 42,398 kg (93,457 lb) |
| Static tipping load, straight, High Lift arrangement | approx. 44,158 kg (97,338 lb) |
| Static tipping load, full 35-degree turn, standard arrangement | approx. 38,242 kg (84,311 lb) |
| Static tipping load, full 35-degree turn, High Lift arrangement | approx. 39,047 kg (86,085 lb) |
Dimensions
| Overall transport length (bucket on ground, standard arrangement) | 12.6-12.86 m (41.4-42.2 ft) |
| Overall length, High Lift arrangement | approx. 13.6 m (44.6 ft) |
| Width over tires | 4.05-4.23 m (13.3-13.9 ft), varies by tire selection |
| Height to top of exhaust stack | 4.73-4.75 m (15.5-15.6 ft) |
| Height over ROPS/FOPS cab | approx. 5.07-5.13 m (16.6-16.9 ft) |
| Wheelbase | 4.6 m (15.1 ft) |
| Tread width | 3.05 m (10 ft) |
| Ground clearance | 0.49-0.51 m (1.6-1.67 ft) |
| Turning circle, outside, standard arrangement | approx. 20.8 m (68.1 ft) |
| Turning circle, outside, High Lift arrangement | approx. 21.5 m (70.6 ft) |
| Articulation (steering) angle | 35 degrees each direction |
| Standard tire size | 41.25/70-39, 42-ply; multiple tire options offered for this model |
Performance
| Maximum travel speed, forward | 22.5 km/h (14 mph) |
| Maximum travel speed, reverse | 25.1 km/h (15.6 mph) |
| Bucket breakout force, standard arrangement | approx. 280 kN (63,066 lbf) |
| Bucket breakout force, High Lift arrangement | approx. 536 kN (120,498 lbf) |
| Static lift/tilt force | approx. 613-618 kN (137,841-139,000 lbf) |
| Bucket capacity range | 8.4-9.2 m3 (11-12 yd3) heaped, depending on bucket selected |
| Hydraulic cycle time | raise approx. 9.2 s, power-down (dump) approx. 2.9 s, lower approx. 3.8 s; total cycle approx. 15.9 s |
| Hydraulic system relief valve setting | approx. 31,000 kPa (4,500 psi) |
| Main hydraulic pump output | approx. 651 L/min (172 gal/min) at 2,128 engine rpm, 6,900 kPa |
| Transmission | Powershift, 3 speeds forward / 3 speeds reverse |
Service capacities (summary)
| Fuel tank | 970 L (256.3 gal) |
| Hydraulic system, total including tank | 435 L (115 gal) |
| Engine crankcase (oil) | 95 L (25.1 gal) |
| Cooling system | 190 L (50.2 gal) |
| Transmission | 110 L (29.1 gal) |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
990 II fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with filter) — Cat 3412E V-12 diesel | 95 L (25.1 US gal) | Cat DEO (Diesel Engine Oil), SAE 15W-40 for temperate/warm climates, SAE 10W-30 for cold-weather starts. Follow S·O·S oil sampling to confirm any interval extension. |
| Cooling system | 190 L (50.2 US gal) | Cat DEAC (Diesel Engine Antifreeze/Coolant), premixed 50/50 with water for standard service, heavier glycol ratio for extreme cold. Cat ELC (Extended Life Coolant) accepted as a longer-interval alternative. |
| Fuel tank | reported between 970 L and 1,563 L (256-413 US gal) depending on source — varies by configuration/series; confirm tank size fitted to this unit | No. 2-D diesel fuel meeting Cat's fuel spec (low-sulfur); No. 1-D or an arctic-blend diesel for cold-weather operation. |
| Transmission (powertrain compartment) | 110 L (29.1 US gal) | Cat TDTO (Transmission/Drive Train Oil), SAE 30 for normal ambient temperatures, SAE 10W for cold-start climates. |
| Front axle (differential and final drives) | 271 L (71.6 US gal) | Cat TDTO, same grade as transmission. |
| Rear axle (differential and final drives) | 261 L (69 US gal) | Cat TDTO, same grade as transmission. |
| Hydraulic system (including tank) — implement, steering and brake circuits | approx. 435 L (115 US gal) total system | Cat TDTO SAE 10W, Caterpillar's standard hydraulic fluid for this class and era of wheel loader; implement, steering and brake circuits share one reservoir and spec. |
| Hydraulic tank (reservoir only) | 174 L (46 US gal) | Cat TDTO SAE 10W, same spec as the full hydraulic system. |
| Grease (spec only) | not applicable — service-point spec only | Cat Multipurpose Grease / Cat Prime Application Grease, NLGI 2, for pins, bushings, and articulation/steering joints. Cat Extreme Application grease for high-load or high-temperature service points. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar 990 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 990 II beyond the schedule
Predictive Maintenance & Fluid Analysis
Run S-O-S oil sampling on the 3412E TA's engine oil, powershift transmission/torque converter, differentials, and hydraulic system at every service interval. Wear-metal trends catch torque converter clutch wear and final-drive planetary wear long before a rebuild becomes unavoidable. Track HEUI injection actuation pressure and fuel dilution readings to flag injector or actuation-pump wear early. Sample coolant condition to catch ELC depletion before it drives liner pitting or water pump wear in this V-12's cooling circuit.
Corrective & Common Repairs
Expect HEUI injector and injection actuation pump wear as the most common fuel-system repair on high-hour 3412E TA engines. Turbocharger bearing wear shows up as boost loss and blue smoke under load. Powershift clutch packs and the lockup torque converter wear from repeated load-and-carry cycles typical of quarry duty. Wet-disc brakes wear faster in load-and-carry service than in general grading work. Center-hinge and articulation bushings loosen on high-cycle machines and need regular play checks.
Overhaul & Rebuild Points
Plan an inframe or top-end overhaul of the 3412E TA once compression, blow-by, and S-O-S wear-metal trends move outside normal range; the V-12 block tolerates rebuilds well and keeps this loader working well past 20,000 hours. Final-drive planetary sets and differentials are the next major rebuild point under sustained quarry loading. Hoist and tilt cylinders need reseals as hour counts climb, and torque converters warrant a rebuild once stall speed or lockup response drifts from spec.
Seasonal & Environment Servicing
Fit cold-weather starting aids, such as a block heater and arctic-grade fuel and coolant, before winter operation; the 3412E TA's HEUI system is harder to prime cold than older mechanical injection. Clean the radiator and air-to-air aftercooler cores often in dusty quarry or aggregate settings to prevent overheating. Service the air precleaner on a shortened interval in high-dust environments. Check tire and rim condition regularly where sharp rock or scrap is handled, and verify coolant freeze protection each season.
990 II common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 9X-8216 | Filter Element-Cab Air | Air intake service | Check fitment → |
| 160-2531 | Frame-Filter | Scheduled service item | Check fitment → |
| 8T-5913 | Screen-Filter | Scheduled service item | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
990 II fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| 100-01 | Engine Oil Pressure - data valid but below normal range (low oil pressure detected by the ECM). | Low oil level, worn oil pump, plugged suction screen or filter, or a drifting oil pressure sensor. | Check oil level and condition first. Confirm with a mechanical gauge before condemning the sensor. Shut down promptly if pressure is confirmed low to avoid engine damage. |
| 110-00 | Engine Coolant Temperature - data valid but above normal range (high coolant temperature). | Low coolant level, blocked radiator core, fan drive or fan clutch fault, stuck thermostat, or a failing water pump. | Check coolant level and clear debris from the radiator core, confirm fan operation, verify the reading with a mechanical thermometer before replacing the sensor. |
| 164-02 | Injection Actuation Pressure - erratic, intermittent, or incorrect reading in the HEUI hydraulic fuel system. | Aerated or low engine oil (the HEUI system uses engine oil as actuation fluid), a faulty IAP sensor, wiring problems, or wear in the actuation pump or control valve. | Check engine oil level and condition, inspect IAP sensor wiring and connector, then run an actuation pressure test with Cat ET. |
| 168-03 | Electrical System Voltage - above normal (overcharge condition on the machine's main electrical circuit). | Faulty voltage regulator or alternator, chafed wiring shorting to a power source, or a bad ground connection. | Check charging system output with a meter, inspect the main harness and ground straps, compare against battery voltage. |
| 168-04 | Electrical System Voltage - below normal (undercharge or weak battery condition). | Discharged or failing batteries, worn alternator brushes or regulator, loose or corroded battery and ground cables, high-resistance connections. | Load-test the batteries, check charging output, clean and tighten all battery and ground connections. |
| 190-08 | Engine Speed/Timing Sensor - abnormal frequency, pulse width, or period (erratic speed signal). | Damaged or misadjusted speed/timing sensor, worn reluctor or gear teeth, or chafed sensor wiring. | Check sensor air gap and mounting, inspect wiring for damage, verify the signal with Cat ET before replacing the sensor. |
| 1-05 | Injector Solenoid Circuit (this cylinder) - current below normal or open circuit; the ECM cannot fire that injector. Same pattern applies across the injector CID range for any of the twelve cylinders. | Open injector solenoid winding, a damaged harness connector at the valve cover, or oil-contaminated injector harness pins. | Inspect the injector harness at the valve cover for oil intrusion or damaged pins. Swap-test the injector and harness between cylinders to isolate injector versus wiring, then repair or replace as needed. |
| 102-03 | Boost Pressure Sensor - voltage above normal (open circuit or short to a power source on the intake manifold pressure signal). | Failed boost pressure sensor, damaged sensor wiring, or a corroded connector; can follow turbocharger work or an overhaul. | Inspect sensor wiring and connector for damage or corrosion, check sensor supply voltage, replace the sensor if it fails a calibration check. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
990 II attachments & work tools
General-purpose buckets
Standard and high-lift arrangement buckets range 8.4-9.2 m³ (11-12 yd³) heaped, with shell-and-tine welded construction, replaceable weld-on wear plates, and an integral rock guard. Buckets mount on shouldered, double-strap adapters with bolt-on cutting-edge segments and interchangeable tip styles.
Aggregate/quarry face-loading bucket
An 8.6 m³ (11.2 yd³) bucket variant is offered for face loading in high-abrasion, moderate-impact quarry and aggregate work, trading some heaped capacity for added wear protection.
High Lift arrangement
Factory high-lift linkage adds roughly 566 mm (22.3 in) of dump clearance and about 293-294 mm (11.5 in) of forward reach over the standard arrangement at full lift and 45-degree dump, letting the loader match larger haul trucks up to around 90 tonnes (100 tons) class without stepping up to a bigger loader. Typical pass counts cited are about 4 passes to fill a 68-tonne (75-ton) class truck and 6 passes for a 91-tonne (100-ton) class truck; buckets are interchangeable between standard and high-lift linkage.
Bucket-mount ground engaging tools
Each bucket accepts up to two sets of pin-on sidebar protectors plus bolt-on cutting-edge segments and multiple tip profiles, all fitted through shouldered double-strap adapters for field replacement without welding.
Tool mounting system
Work tools pin directly to the single-tilt Z-bar loader linkage (cast cross tube, cast tilt lever, solid-plate lift arms, serviceable grease B-pin, center-point articulation). This large-wheel-loader class is not documented with a hydraulic quick-coupler of the type offered on Cat's smaller and medium wheel loaders, so tool changes are pin-and-retainer jobs rather than in-cab swaps.
Climate and duty guarding packages
A high-ambient cooling package rated to 50°C (122°F) is available for hot-climate sites, and additional structural guarding is offered for harsh-duty environments such as steel-mill or heavy-quarry work. Integrated axle cooling paired with ride control is recommended for load-and-carry applications.
Tire options
Multiple tire choices are available to suit ground conditions and duty cycle; published performance specs are typically measured with 41.25/70-39, 42-ply tires as the reference fitment.
Auxiliary hydraulics for powered tools
Tools needing a powered function, such as grapple-style attachments, require an auxiliary or third-function hydraulic circuit. This is not documented as a standard factory-listed option for this model in available literature — confirm availability and kit specifics with a Cat dealer before ordering a powered tool.
All 990 II assemblies by section
Every catalogued assembly group for the Caterpillar 990 II. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Braking System
144-7237 Accumulator Gp-Brake
| 03***13 | Screw-Forming; (10-24x0.37-In) | 2 |
| 06***35 | Valve-Gas | 1 |
| 06***36 | Protector-Gas Valve | 1 |
112-0874 Brake Gp-Service
| 10***06 | Dowel-Hollow; (35.0 Odx45.0mm Oal) | 8 |
| 11***74 | Brake Group-Service | 1 |
| 11***58 | Seal; (409.2mm Id) | 1 |
112-2273 Control Gp-Foot Brake
| 00***01 | Ring-Retaining | 10 |
| 11***73 | Control Group-Foot Brake | 1 |
| 11***76 | Harness As-Brake; (Right Ft Brake Base) | 1 |
4e-6401 Control Gp-Parking Brake
| 09***67 | Pin-Clevis | 1 |
| 12***71 | Knob | 1 |
| 3E***67 | Cable As-Parking Brake Control | 1 |
2q-8172 Control Gp-Parking Brake -Custom
| 03***48 | Clip; (11.11mm .437in Id) | 7 |
| 07***26 | Angle | 1 |
| 09***45 | Washer; (16.6x24x1.2-mm Thk) | 2 |
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 |
Electrical And Starting System
3e-6328 Alarm Gp
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 3E***28 | Alarm Group; -Caterpillar Monitoring System-Action | 1 |
| 8T***29 | Pin-Connector; (16-Ga To 18-Ga)(Throttle Position Sensor) | 2 |
3e-6389 Lamp Gp-Dome
| 10***03 | Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge) | 1 |
| 3E***71 | Wedge; (Receptacle Lock) (3 Pin) | 1 |
| 3E***89 | Lamp Group-Dome; -With Switch-Cab, Rh, Lh | 1 |
176-1602 Sensor Gp-Position
| 10***03 | Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge) | 1 |
| 17***02 | Sensor Group-Position; -Accelerator Control | 1 |
| 3E***71 | Wedge; (Receptacle Lock) (3 Pin) | 1 |
147-1680 Sensor Gp-Position -Tc Impeller Clutch
| 10***03 | Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge) | 1 |
| 14***80 | Sensor Group-Position; -Direction, Speed-Steering Pedal, Rh, Lh-Center Pedal | 1 |
| 3E***71 | Wedge; (Receptacle Lock) (3 Pin) | 1 |
9x-5592 Sensor Gp-Position -Tc Impeller Clutch
| 10***03 | Kit; (Receptacle) (3-Pin) (Includes Receptacle As & Wedge) | 1 |
| 3E***71 | Wedge; (Receptacle Lock) (3 Pin) | 1 |
| 8T***29 | Pin-Connector; (16-Ga To 18-Ga)(Throttle Position Sensor) | 3 |
164-7577 Switch Gp-Bypass
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 16***77 | Switch Group-Bypass; -Xmsn Lubrication Supply Filter-Xmsn Lubrication Charge Filter-Hoist Screen-Tc, Front Brake Cooling-Transmission Oil Filter-Rear Axle Oil Filter | 1 |
| 3D***24 | O-Ring - For Oil Drain & Level Plug (Items 3 & 7) | 1 |
3e-0075 Switch Gp-Magnetic -Start Relay
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 3E***75 | Switch Group-Magnetic; -Air Inlet Heater, Start Relay | 1 |
9g-7641 Switch Gp-Start
| 6V***62 | Screw-Machine; (8-32x0.31-In) | 4 |
| 7T***99 | Nut-Mounting; (1-32-Thd) | 1 |
| 9B***33 | Lockwasher; (Int'L Tooth) | 4 |
3e-0155 Switch Gp-Wiper
| 01***16 | Setscrew; (8-32x0.5-In) | 1 |
| 10***06 | Receptacle Kit; (Includes Wedge And Receptacle Assem.) | 1 |
| 2H***20 | Lockwasher (11.38mm Id) | 1 |
105-3025 Valve Gp-Solenoid -Tc Impeller Clutch
| 01***27 | Nut-Stamped | 1 |
| 10***65 | Spacer | 1 |
| 10***67 | Kit-Seal | 1 |
105-3030 Valve Gp-Solenoid -Tc Lockup Clutch
| 01***27 | Nut-Stamped | 1 |
| 10***65 | Spacer | 1 |
| 10***67 | Kit-Seal | 1 |
123-8363 Wiring Gp-Cab
| 12***63 | Wiring Group-Cab | 1 |
| 12***23 | Harness As-Cab; (Floodlights, Wipers, A/C) | 1 |
| 12***24 | Harness As-Cab; (Monitor, Instrument Panel) | 1 |
2q-8237 Wiring Gp-Cab -Custom
| 03***22 | Spacer-Generator Mounting | 2 |
| 07***32 | Rod | 1 |
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
2q-8196 Wiring Gp-Engine -Custom
| 03***48 | Clip; (11.11mm .437in Id) | 1 |
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 10***25 | Valve Group-Solenoid; -Tc Impeller Clutch | 1 |
2q-8198 Wiring Gp-Engine Electronic -Custom
| 0S***09 | Bolt (3/4") Filler Tube Assembly To Transfer Drive Case | 1 |
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 1 |
| 0S***20 | Bolt--Customer Grounding Bolt | 1 |
2q-8202 Wiring Gp-Machine -Custom
| 03***48 | Clip; (11.11mm .437in Id) | 1 |
| 10***83 | Angle As | 1 |
| 10***13 | Angle | 1 |
2q-8301 Wiring Gp-Machine -Custom
| 03***48 | Clip; (11.11mm .437in Id) | 3 |
| 13***90 | Gasket-Connector | 2 |
| 13***88 | Nut-Ring | 2 |
2q-8200 Wiring Gp-Relay Panel -Custom
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 10***04 | Suppressor As-Arc | 1 |
| 11***31 | Film; (Identification) (On Fuse Box Near Diagnostick Connector) | 1 |
Frame And Body
2q-7656 Counterweight Gp-Rear -Custom
| 2Q***56 | Counterweight Group; -Custom | 1 |
| 2Q***45 | Plate As | 1 |
| 3V***93 | Eye; (Lifting) | 4 |
2q-7437 Enclosure As-Hydraulic Tank -Custom
| 2Q***37 | Enclosure As-Hydraulic Tank; -Custom | 1 |
| 8T***97 | Nut-Weld; (M12x1.75-Thd) | 5 |
2q-4350 Hardware Gp-Rear Frame -Custom
| 11***23 | Stud-Weld; (M10x1.5x25-mm) | 2 |
| 2Q***50 | Frame As-Rear; -Custom | 1 |
2z-9450 Insulation Ar-Heat -Custom
| 2Q***62 | Shield-Heat; (Hydraulic Tank Hose) | 1 |
| 2Q***48 | Insulation Group-Heat; -Control Valve Lines-Custom | 1 |
| 2Q***49 | Insulation Group-Heat; -Pilot Lines-Custom | 1 |
2q-7152 Insulation Gp-Heat -Lift Lines-Custom
| 2Q***53 | Insulation; (146-cm Each) | 0 |
| 2Q***52 | Insulation Group-Heat; -Lift Lines-Custom | 1 |
| 5P***68 | Clamp-Hose; (Us Sourced) | 20 |
2q-7151 Insulation Gp-Heat -Hydraulic Lines-Custom
| 2Q***53 | Insulation; (146-cm Each) | 0 |
| 2Q***51 | Insulation Group-Heat; -Hydraulic Lines-Custom | 1 |
| 5P***68 | Clamp-Hose; (Us Sourced) | 4 |
2q-7184 Insulation Gp-Heat -Ride Control Lines-Custom
| 2Q***84 | Insulation; (124-cm Each) | 0 |
| 2Q***53 | Insulation; (146-cm Each) | 0 |
| 2Q***84 | Insulation Group-Heat; -Ride Control Lines-Custom | 1 |
2q-7154 Insulation Gp-Heat -Brake Lines-Custom
| 2Q***84 | Insulation; (124-cm Each) | 0 |
| 2Q***54 | Insulation Group-Heat; -Brake Lines-Custom | 1 |
| 5P***97 | Clamp Fumes Disposal | 6 |
2q-7153 Insulation Gp-Heat -Tilt Lines-Custom
| 2Q***53 | Insulation; (146-cm Each) | 0 |
| 2Q***53 | Insulation Group-Heat; -Tilt Lines-Custom | 1 |
| 5P***68 | Clamp-Hose; (Us Sourced) | 8 |
2q-7149 Insulation Gp-Heat -Pilot Lines-Custom
| 2Q***04 | Insulation; (70-cm Each) | 0 |
| 2Q***49 | Insulation Group-Heat; -Pilot Lines-Custom | 1 |
| 6D***41 | Clip-To Harness Routed Along Lh Side | 5 |
2q-7148 Insulation Gp-Heat -Control Valve Lines-Custom
| 2Q***53 | Insulation; (146-cm Each) | 0 |
| 2Q***48 | Insulation Group-Heat; -Control Valve Lines-Custom | 1 |
| 5P***68 | Clamp-Hose; (Us Sourced) | 6 |
2q-7155 Insulation Gp-Heat -Steering Lines-Custom
| 2Q***84 | Insulation; (124-cm Each) | 0 |
| 2Q***55 | Insulation Group-Heat; -Steering Lines-Custom | 1 |
| 5P***97 | Clamp Fumes Disposal | 4 |
2q-7150 Insulation Gp-Heat -Front Wiring-Custom
| 2Q***04 | Insulation; (70-cm Each) | 0 |
| 2Q***50 | Insulation Group-Heat; -Front Wiring-Custom | 1 |
2q-8238 Step Gp -Custom
| 13***52 | Step As | 3 |
| 13***54 | Bracket | 2 |
| 16***26 | Plate | 2 |
Hydraulic System
123-8364 Control Gp-Hydraulic Hand
| 10***43 | Hose As | 1 |
| 11***20 | Switch As-Push Button; (Horn) | 1 |
| 12***80 | Actuator-Rocker | 1 |
4e-9264 Lock Gp-Hydraulic Hand Control
| 13***22 | Gate | 1 |
| 3B***07 | Cotter--Yoke Assembly | 2 |
| 4E***01 | Knob | 1 |
6e-3796 Valve Gp-Pilot
| 10***05 | Kit-Receptacle; (6-Pin)(Display Monitor Harness) | 1 |
| 10***20 | Rod | 3 |
| 10***21 | Valve Group-Pilot; -Bucket | 1 |
177-4104 Valve Gp-Pilot
| 17***04 | Valve Group-Pilot; -2-Function | 1 |
| 17***06 | Valve Group-Pilot; -Tilt | 1 |
| 17***07 | Valve Group-Pilot; -Lift | 1 |
177-4107 Valve Gp-Pilot
| 11***32 | Plate-Orifice | 2 |
| 17***07 | Valve Group-Pilot; -Lift | 1 |
| 17***09 | Valve Group-Pressure Reducing | 2 |
177-4106 Valve Gp-Pilot
| 11***32 | Plate-Orifice | 2 |
| 17***06 | Valve Group-Pilot; -Tilt | 1 |
| 17***09 | Valve Group-Pressure Reducing | 2 |
108-0221 Valve Gp-Pilot -Bucket
| 10***72 | Boot | 1 |
| 10***73 | Clamp-Boot | 1 |
| 10***29 | Bracket-Pivot | 1 |
108-0222 Valve Gp-Pilot -Lift
| 10***72 | Boot | 1 |
| 10***73 | Clamp-Boot | 1 |
| 10***29 | Bracket-Pivot | 1 |
116-3045 Valve Gp-Pilot Cartridge
| 03***28 | Seal-O-Ring | 1 |
| 11***44 | Seat-Spring | 1 |
| 11***45 | Valve Group-Pilot Cartridge | 1 |
112-3628 Valve Gp-Pilot Cartridge
| 10***46 | Seat-Spring | 1 |
| 10***58 | Plunger | 1 |
| 10***59 | Spring | 1 |
116-3101 Valve Gp-Pilot Cartridge
| 10***46 | Seat-Spring | 1 |
| 11***01 | Oil Line, Valve Group-Pilot Cartridge | 1 |
| 11***00 | Plunger | 1 |
112-7106 Valve Gp-Pilot Cartridge
| 10***46 | Seat-Spring | 1 |
| 10***58 | Plunger | 1 |
| 10***59 | Spring | 1 |
4z-6239 Valve Gp-Relief -Custom
| 3J***07 | Seal Valve Assembly To; Seal- Tube Assembly To Logic Valve | 2 |
| 4J***24 | Seal 46.99 mm(1.85 In.) I.D. | 2 |
| 4Z***39 | Valve Group-Relief; -Custom | 1 |
4z-6240 Valve Gp-Relief -Custom
| 3K***60 | Seal Pilot Manifold On; Seal To Boom Check Valve Drain | 1 |
| 4J***22 | Seal-Interface Between 3rd & Tilt Valve | 1 |
| 4T***70 | Spring | 1 |
Implements
2z-9451 Pin Gp-Slag Bucket -Custom
| 1R***52 | Seal As | 4 |
| 2H***33 | Seal ("O" Ring) | 2 |
| 2Q***55 | Plate | 2 |
Machine Arrangement
2q-8224 Mill Ar-Steel -Custom
| 11***92 | Wiring Group-Engine | 1 |
| 12***36 | Wiring Group-Machine | 1 |
| 12***40 | Wiring Group-Engine | 1 |
Operator Station
118-7645 Air Conditioner Ar
| 11***45 | Air Conditioner Ar | 1 |
| 12***76 | Air Conditioner Group | 1 |
| 12***14 | Duct Group-Air | 1 |
123-8576 Air Conditioner Gp
| 03***91 | Pop - Rivet (To Secure Safety Lable) | 4 |
| 10***02 | Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness) | 1 |
| 10***05 | Kit-Receptacle; (6-Pin)(Display Monitor Harness) | 1 |
123-8708 Box Gp-Storage
| 10***95 | Lid As | 1 |
| 12***08 | Box Group-Storage | 1 |
| 12***09 | Cover | 1 |
2q-8189 Cab & Platform Gp -Custom
| 12***25 | Platform Group-Cab | 1 |
| 12***01 | Door Group-Lh; -Lh | 1 |
| 2Q***89 | Cab & Platform Group; -Custom | 1 |
2q-8188 Cab Ar -Custom
| 11***73 | Control Group-Foot Brake | 1 |
| 11***63 | Pedal Group-Governor | 1 |
| 11***10 | Sealing Group-Glass | 1 |
123-7023 Cab Gp
| 10***63 | Bracket-Rear | 2 |
| 10***91 | Screw; (Flat Head) (No.6-20x0.5in) | 20 |
| 11***24 | Button | 1 |
103-8529 Control Gp-Cms Display
| 10***29 | Control Group-Cms Display; -Computerized Monitoring System | 1 |
| 15***03 | Control Group-Cms Display | 1 |
123-8701 Door Gp-Lh
| 12***01 | Door Group-Lh; -Lh | 1 |
| 3E***00 | Seal; (580-cm) | 0 |
| 4E***05 | Handhold | 1 |
123-8714 Duct Gp-Air
| 12***14 | Duct Group-Air | 1 |
| 12***15 | Duct | 1 |
| 12***16 | Duct | 1 |
8y-6883 Extension Gp-Backrest
| 11***30 | Kit-Cushion; (Cloth Backrest) | 1 |
| 8Y***77 | Pan As-Extension | 1 |
| 8Y***47 | Fastener | 2 |
4e-9439 Filter Gp-Cab Air
| 16***31 | Frame-Filter | 1 |
| 16***62 | Duct As | 1 |
| 2R***76 | Washer .787mm(.031 In.)Thick | 2 |
4e-6409 Installation Gp-Radio
| 03***13 | Screw-Forming; (10-24x0.37-In) | 2 |
| 10***40 | Harness As-Radio | 1 |
| 11***33 | Converter-Power; (24-Volt To 12-Volt) | 1 |
9u-2675 Installation Gp-Radio
| 13***22 | Cable As-Coaxial | 1 |
| 7K***81 | Strap-Pressure & Return Hoses To | 1 |
| 9U***34 | Cable As-Coaxial | 1 |
131-1126 Latch Gp-Cab Door & Window
| 09***84 | Locknut; (M12x1.75-Thd) | 1 |
| 10***54 | Seal; (1040-cm) | 0 |
| 10***45 | Pin-Spring | 1 |
118-7642 Liner Gp-Cab
| 10***54 | Seal; (1040-cm) | 0 |
| 11***42 | Liner Group-Cab | 1 |
| 12***85 | Panel As-Trim | 1 |
130-6907 Mounting Gp-Cab
| 13***07 | Mounting Group-Cab | 1 |
| 4E***84 | Cover As | 2 |
| 4E***96 | Cover | 3 |
2q-8187 Operator Ar -Custom
| 12***23 | Cab Group | 1 |
| 13***07 | Mounting Group-Cab | 1 |
| 2Q***87 | Operator Ar; -Custom | 1 |
108-8421 Pan Gp-Seat -Back
| 10***21 | Pan Group-Backrest; -Seat Back | 1 |
| 10***23 | Shaft As-Lumbar | 1 |
| 10***24 | Pan-Lumbar | 1 |
8y-5992 Pan Gp-Seat -Bottom
| 3K***97 | Pin 3.18 mm(.125 In.) Diameter | 4 |
| 6V***56 | Ring-Retaining | 2 |
| 8Y***92 | Pan As-Seat; (Bottom) | 1 |
123-8361 Panel Gp-Instrument
| 10***29 | Control Group-Cms Display; -Computerized Monitoring System | 1 |
| 12***61 | Panel Group-Instrument; -Front | 1 |
| 12***53 | Film-Face; (Lh)(Cat) | 1 |
123-8362 Panel Gp-Instrument
| 10***06 | Receptacle Kit; (Includes Wedge And Receptacle Assem.) | 1 |
| 11***85 | Knob-Wiper Switch; (Rear) | 1 |
| 11***79 | Potentiometer As; (Temperature Control) | 1 |
113-4799 Pedal Gp-Governor
| 11***99 | Pedal Group-Governor | 1 |
| 12***31 | Cover | 1 |
| 14***61 | Kit-Roller; (Foot Brake Control)(Governor Pedal) | 1 |
112-5763 Pedal Gp-Governor
| 11***63 | Pedal Group-Governor | 1 |
| 11***99 | Pedal Group-Governor | 1 |
| 8T***89 | Bolt (20mm Long) 0 Degrees); (L=20mm) {For 5br, 6cr} | 4 |
6v-6561 Wiper Pivot Gp
| 6A***18 | Washer; (8.1x12.5x1-mm Thk) | 1 |
| 6V***07 | Shaft As; (Pivot) | 1 |
| 6V***09 | Cap-Wiper | 1 |
123-7025 Platform Gp-Cab
| 12***25 | Platform Group-Cab | 1 |
| 12***26 | Platform As | 1 |
| 4E***95 | Door As | 1 |
148-2228 Screen Gp-Sun
| 10***48 | Bracket | 2 |
| 10***51 | Guide | 1 |
| 10***52 | Knob | 1 |
117-1410 Sealing Gp-Glass
| 11***10 | Sealing Group-Glass | 1 |
| 11***81 | Adhesive; (All Joints To Be Sealed) | 1 |
156-1148 Seat Belt Gp
| 15***48 | Seat Belt Group; -Retractable-Operator | 1 |
| 1A***50 | Bolt (7/16-20x1.75in); (7/16-20x1.75-In) | 1 |
| 4D***32 | Locknut (7/16-20 Thd) | 1 |
124-7736 Seat Gp -Cloth
| 06***03 | Shim (.060mm Thk); (1.52-mm Thk) | 4 |
| 09***78 | Pin-Spring | 1 |
| 10***76 | Screw-Hex Socket; (3/8-16x2.25-In) | 6 |
124-7735 Seat Gp
| 12***35 | Seat Group | 1 |
| 12***36 | Seat Group; -Cloth | 1 |
| 15***48 | Seat Belt Group; -Retractable-Operator | 1 |
123-8692 Seat Gp-Suspension
| 12***92 | Seat Group-Suspension | 1 |
| 12***35 | Seat Group | 1 |
| 14***04 | Suspension Group-Seat; -Air | 1 |
131-0441 Spring Gp-Cab Door
| 11***89 | Rod | 1 |
| 13***41 | Spring Group-Cab Door | 1 |
| 2D***35 | Grommet 20.64 mm(.813 In.)O.D. | 1 |
123-8682 Support Gp-Hydraulic Control
| 09***58 | Screw-Machine; (M6x1x14-mm) | 4 |
| 10***94 | Track-Rh | 1 |
| 12***82 | Support Group-Hydraulic Control | 1 |
123-8704 Support Gp-Steering Control
| 01***02 | Lockwasher | 1 |
| 09***58 | Screw-Machine; (M6x1x14-mm) | 4 |
| 09***47 | Nut-Thin; (M16x2 Thd) | 1 |
149-2404 Suspension Gp-Seat -Air
| 10***17 | Bumper | 4 |
| 12***57 | Shaft | 2 |
| 12***66 | Kit-Wiring Harness; (Air Suspension Seat) | 1 |
9u-0351 Washer Gp-Window
| 3S***93 | Strap-Cable-To Tie Harnesses Together | 1 |
| 4E***99 | Harness As-Window Wiper; (And Window Washer) | 1 |
| 7T***90 | Pump As; (Washer) | 2 |
2q-8190 Window Gp -Custom
| 10***54 | Seal; (1040-cm) | 0 |
| 10***15 | Hinge-Rh | 2 |
| 2Q***90 | Window Group; -Custom | 1 |
8r-5535 Wiper & Washer Gp-Window
| 0S***97 | Capscrew (1/4 - 28 Nf X 1 Gd8, Hex) | 2 |
| 3E***08 | Wiper Group-Window; -Rear | 1 |
| 3E***91 | Wiper Group-Window; -Front | 1 |
3e-7508 Wiper Gp-Window -Rear
| 3C***84 | Screw-Machine; (M5x0.8 Bg Thd) | 4 |
| 3E***83 | Wedge-Receptacle Lock; (6-Pin) | 1 |
| 3E***88 | Motor As-Window Wiper; (24-Volt) | 1 |
3e-9291 Wiper Gp-Window -Front
| 3C***84 | Screw-Machine; (M5x0.8 Bg Thd) | 4 |
| 3E***83 | Wedge-Receptacle Lock; (6-Pin) | 1 |
| 3E***88 | Motor As-Window Wiper; (24-Volt) | 1 |
Power Train
152-5273 Axle Ar-Fixed -Custom
| 15***31 | Gear Group-Differential & Bevel; -Custom | 1 |
| 15***16 | Wheel Group-Final Drive & Brake; -Custom | 2 |
| 15***71 | Axle Group-Fixed; -Custom | 1 |
152-5276 Axle Ar-Oscillating -Custom
| 15***31 | Gear Group-Differential & Bevel; -Custom | 1 |
| 15***31 | Axle Group-Oscillating; -Custom | 1 |
| 15***16 | Wheel Group-Final Drive & Brake; -Custom | 2 |
152-5271 Axle Gp-Fixed -Custom
| 10***06 | Dowel-Hollow; (35.0 Odx45.0mm Oal) | 4 |
| 15***02 | Shaft-Axle | 2 |
| 15***51 | Bolt; (M30 X 3.5 X 420) | 16 |
152-2131 Axle Gp-Oscillating -Custom
| 15***31 | Axle Group-Oscillating; -Custom | 1 |
| 1A***60 | Capscrew, Hex Head (1/2 - 13 X 2 G5); (Hex Head) (1/2-13x2 Gd 8 Z) | 12 |
| 1D***08 | Bolt-(3/4" X 2-3/4")-Rops Mounting Bracket To Fender | 16 |
2q-8306 Control Ar-Transmission -Custom
| 2Q***37 | Wiring Group-Cab; -Custom | 1 |
| 2Q***01 | Wiring Group-Machine; -Custom | 1 |
| 2Q***06 | Control Ar-Transmission; -Override | 1 |
159-8661 Control Gp-Stic
| 10***29 | Actuator | 1 |
| 10***73 | Grip | 1 |
| 15***61 | Control Group-Stic | 1 |
4e-8413 Control Gp-Stic
| 15***61 | Control Group-Stic | 1 |
| 4E***20 | Base | 1 |
| 4E***27 | Housing | 1 |
177-4113 Control Gp-Stic
| 09***62 | Washer; (Hard) (3.4x7x0.8mm Thk) | 2 |
| 10***29 | Actuator | 1 |
| 10***73 | Grip | 1 |
151-6409 Differential Gp
| 12***51 | Case As-Differential | 1 |
| 15***95 | Gear-Differential | 2 |
| 15***09 | Differential Group | 1 |
151-6431 Differential & Bevel Gear Gp -Custom
| 03***57 | Bolt; --To Reverse Shaft Bearing Retainer & Forward Shaft Bearing Retainer | 6 |
| 0S***87 | Bolt-Bracket Assembly To Timing Gear | 4 |
| 10***17 | Shaft-Bevel Pinion | 1 |
9u-4979 Lock Gp-Stic Control
| 10***04 | Kit-Receptacle; (4-Pin)(Start Switch) | 1 |
| 10***60 | Switch As-Limit; (Stic Control Lock) | 1 |
| 14***65 | Lever As | 1 |
151-6975 Wheel & Final Drive Gp -Custom
| 03***35 | Bolt-Self Locking; 2.22cm(.875 In.) Lg | 4 |
| 0S***85 | Bolt; 12.7 mm (1/2") Diameter X 38.1 mm (1 1/2") Length Generator To Engine | 9 |
| 10***95 | Shim Pack; (Includes 16-Shims) | 1 |
152-3016 Wheel & Final Drive Gp -Custom
| 11***74 | Brake Group-Service | 1 |
| 15***75 | Wheel Group-Final Drive; -Custom | 1 |
| 15***16 | Wheel Group-Final Drive & Brake; -Custom | 1 |
Steering System
130-1830 Control Gp-Steering
| 09***14 | Hose As | 2 |
| 10***96 | .. Bearing., Plate | 2 |
| 12***71 | Harness As-Steering; (Stic Control)(Stic Control Jumper Harness) | 1 |
143-2855 Valve Gp-Pilot -Steering-Stic Steering
| 09***19 | Seal-O-Ring (Id=15.80mm) | 2 |
| 10***18 | Shim; (.020in Thk) | 2 |
| 10***19 | Shim; (0.762-mm Thk) | 2 |
990 II serial number reference
The PIN plate on a 990 II sits on the left (highway) side of the machine frame, behind the front tire, near the articulation joint. Pre-2001 machines show a short 8-character number: a 3-character prefix (letters/numbers) followed by a 5-digit sequence, e.g. 4FR00378 - the sequence counts up within that prefix as machines are built. From 2001 the plate shows a full 17-character PIN starting with CAT, with the model code, a check character, plant code, and unit sequence packed into the remaining characters; the old-style 3-character prefix logic still sits inside that string but is harder to isolate without a dealer SIS lookup.
| Prefix | Identifies | Notes |
|---|---|---|
| 4FR | 990 Series II (990 II) wheel-type loader, standard-lift configuration | Fitted with the Cat 3412E TA V12 diesel. Gross power 503 kW / 675 hp; net power (ISO 9249) 466 kW / 625 hp; flywheel power about 463 kW / 620 hp. Machines on this prefix are on record from the late 1990s, with sequence numbers into the 600-range by 1999, and the block runs toward the mid-2000s. For the 2002 model year, engine software and the cooling package were revised (air-to-air aftercooling) to meet Tier 2 / Stage II emissions. |
| BCR | 990 Series II (990 II) wheel-type loader, later production | Same Cat 3412E TA diesel as the rest of the Series II run. This block covers later-build machines, seen on units dated 2003-2005. Confirm exact build date and configuration with your dealer using the full PIN. |
Frequently asked questions
What engine does the Caterpillar 990 II wheel loader use?
The 990 II uses a Caterpillar 3412E TA V-12 diesel with HEUI electronic unit injection and ADEM III engine controls, air-to-air aftercooling, and Tier 2 emissions compliance. Gross power is rated around 503 kW (675 hp), with flywheel/net output near 466 kW (625 hp).
What is the operating weight of the Caterpillar 990 II?
Operating weight runs about 73.5 t (162,000 lb) in standard configuration, rising to roughly 83 t (183,500 lb) for High Lift and quarry-duty setups with larger buckets or added counterweighting. Exact weight varies by bucket, tires, and factory configuration.
What replaced the Caterpillar 990 II wheel loader?
Caterpillar replaced the 990 II with the 990H, which carries a Cat C27 ACERT engine in place of the 990 II's 3412E TA. The 990 II itself succeeded the original 990, which used an earlier mechanically-injected 3412.
What 990 II owners discuss
How does the 990 II's engine differ from other 990-series generations?
The 990 Series II runs the Cat 3412E, a turbocharged and air-to-air aftercooled V-12 with ADEM III electronic control and a HEUI (hydraulically actuated electronic unit injection) fuel system. That combination is specific to the II: the original 990 ran an earlier mechanically-governed 3412 without ADEM or HEUI, and later 990H/990K generations moved to different Cat engine families entirely. Owners and techs comparing notes across the 990 lineup consistently flag this as the detail that trips people up when pulling troubleshooting advice or spec sheets off the wrong generation. Confirm the engine serial prefix on the build plate before applying fault-code or injector guidance found for a sibling 990.
What powertrain issue comes up most for the 990 II's HEUI fuel system?
Repeat injector failure concentrated in one or two cylinders, paired with a rising iron trend in oil samples, is the early warning mechanics watch for on this HEUI-equipped V-12. The root cause reported most often is wear in the HEUI pump's thrust bearing, which sheds metal into engine oil and then into the injectors themselves. Oil sampling on a roughly 250-hour cycle is the standard practice for catching that iron trend before injectors fail outright. Engines with disciplined sampling and clean oil have reportedly run well past 20,000 hours on original injectors, so failure tracks maintenance discipline more than raw hours. Have your dealer verify HEUI pump condition and oil analysis trend before condemning injectors on a fault code alone.
What should operators know about cold-starting a 990 II?
The 3412E in the 990 II uses glow-plug (heat-start) cold-start assist, not an ether system. The standing warning among diesel techs is not to mix the two: dosing ether into a glow-plug engine can snap the glow plug tips off inside the cylinder and cause internal engine damage. When a 990 II is genuinely hard to start cold, the fault trail usually leads to a weak glow plug relay, corroded heat-start wiring, or marginal battery and starter capacity rather than a fuel system problem. Have your dealer verify the glow plug circuit and cold-start logic if hard starting persists after basic battery and connection checks.
What drivetrain behavior should owners watch for on the 990 II?
The 990 II's impeller-clutch torque converter with lock-up, paired with its Rimpull Control System, is meant to cut tire slip and heat buildup once the converter locks up during a loading cycle. Across large Cat wheel loaders sharing this general torque-converter architecture, the recurring field complaint is transmission oil overheating tied to a failing trans oil cooler or trans pump rather than a defect in the lock-up clutch design itself. Watch the transmission oil temperature gauge on repeated hot digging or load-and-carry cycles; repeated over-temp events are the signal to pull pressures, not routine wear. Have your dealer verify torque converter and transmission pressures if overheating recurs.
What wear pattern shows up on the 990 II's loader linkage?
The 990 II uses a single-tilt Z-bar loader linkage with serviceable grease pins at the bucket pivot and center-point frame articulation; some machines carry an optional auto-lube system. Mechanics servicing this class of loader are consistent on one point: fast pin and bushing wear almost always traces back to skipped or stretched grease intervals rather than a parts defect, with dirt intrusion and misalignment following once lubrication lapses. Daily or every 8-10 hour greasing is the interval usually cited. Watch for excessive play at the bucket pivot or a knock during lift-tilt cycling as the first sign bushings need replacing, before pins start scoring the bore.
What electrical or sensor issues get reported on the 990 II?
When a 990 II throws an injector or driver-related fault, techs report checking wiring and connectors before suspecting the ADEM III ECM itself. Corroded harness connectors and damaged terminal pins on this engine family have produced intermittent high-voltage or short-type fault codes that look like an injector driver failure but trace back to a wiring fault, including a documented case of oil intrusion into a connector housing causing a false overvoltage code. ECM power supply and ground connections are another commonly overlooked check. Have your dealer verify wiring continuity and connector condition with factory diagnostic software before replacing ECM or injector components on a fault code alone.
What should a buyer check before purchasing a used 990 II?
Buyers shopping a used 990 II consistently check the same short list: confirm the oil pressure fault indicator clears normally on startup and stays in range under load; verify hour meter reading against service records rather than trusting the sale listing alone; inspect tire tread depth and sidewall condition, since replacement rubber is a major cost at this machine's size; cycle the Z-bar linkage through full lift-dump-tilt travel and check for play at the bucket pivot pins; and run the machine through a load cycle to confirm smooth torque converter lock-up with no lag, shudder or overheating. Request recent oil sample history if the seller has it, since iron trend data is the best available predictor of HEUI pump and injector health on this engine. Have your dealer pull the full fault code history and review oil analysis records before final purchase.
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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