Caterpillar 633B
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar 633B is a heavy-duty wheel tractor-scraper designed for high-production earthmoving and mass excavation. This machine belongs to the heavy-weight class of scrapers, utilizing a powerful engine configuration to drive large-scale material transport. The series is characterized by its ability to handle significant payloads through various bowl configurations, including open bowl and elevator arrangements. It serves as a critical component in fleets requiring rapid cycle times for loading and hauling operations.
Across the 633B production lifecycle, refinements focused on improving engine efficiency and hydraulic horsepower for better loading performance. The machine remains highly relevant in the used equipment market due to its robust construction and the availability of standardized Caterpillar maintenance protocols. For fleet managers, the 633B represents a durable asset where parts availability and established service intervals allow for predictable ownership costs and high machine uptime.
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 633B specifications
Engine
| Model | 3408E |
| Net Power (Gears 1-2) | 335 kW (450 hp) |
| Net Power (Gears 3-8) | 365 kW (490 hp) |
| Gross Power (Gears 1-2) | 354 kW (475 hp) |
| Gross Power (Gears 3-8) | 384 kW (515 hp) |
| Displacement | 18 l (1099 in³) |
| Bore | 137 mm (5.4 in) |
| Stroke | 152 mm (6 in) |
Weights
| Total Operating Weight (Empty) | 51066 kg (the OEM part reference lb) |
| Total Operating Weight (Loaded) | 88260 kg (the OEM part reference lb) |
| Total Shipping Weight | 50526 kg (the OEM part reference lb) |
| Tractor Shipping Weight | 21000 kg (46200 lb) |
| Scraper Shipping Weight | 29526 kg (64958 lb) |
| Front Axle Weight (Empty) | 32682 kg (72051 lb) |
| Rear Axle Weight (Empty) | 18384 kg (40529 lb) |
| Front Axle Weight (Loaded) | 45013 kg (99236 lb) |
| Rear Axle Weight (Loaded) | 43247 kg (95344 lb) |
Dimensions
| Overall Machine Length | 14812 mm (583.2 in) |
| Overall Machine Width | 4050 mm (159.5 in) |
| Overall Shipping Height | 4240 mm (166.9 in) |
| Wheel Base | 9021 mm (355.2 in) |
| Height to Top of Cab | 3715 mm (146.3 in) |
| Width of Tractor | 3481 mm (137 in) |
| Width - Outside Rear Tires | 3636 mm (143.2 in) |
| Width - Inside of Bowl | 3405 mm (134 in) |
| Maximum Ground Clearance | 502 mm (19.8 in) |
Performance
| Travel Speed (Gear 1) | 4.8 km/h (3 mile/h) |
| Travel Speed (Gear 2) | 8.5 km/h (5.3 mile/h) |
| Travel Speed (Gear 3) | 11.9 km/h (7.4 mile/h) |
| Travel Speed (Gear 4) | 16.3 km/h (10.1 mile/h) |
| Travel Speed (Gear 5) | 21.7 km/h (13.5 mile/h) |
| Travel Speed (Gear 6) | 29.5 km/h (18.3 mile/h) |
| Travel Speed (Gear 7) | 39.8 km/h (24.7 mile/h) |
| Travel Speed (Gear 8) | 53.8 km/h (33.4 mile/h) |
| Reverse Speed | 9.9 km/h (6.2 mile/h) |
| Scraper Capacity - Heaped | 26 m³ (34 yd³) |
| Scraper Capacity - Struck | 17.7 m³ (23.2 yd³) |
| Rated Load | 37200 kg (82000 lb) |
| Steering Angle - Right | 90 Degrees |
| Steering Angle - Left | 85 Degrees |
Service capacities (summary)
| Fuel Tank | 814 l (215 gal US) |
| Crankcase | 45 l (11.7 gal US) |
| Transmission | 127 l (33 gal US) |
| Differential | 136 l (36 gal US) |
| Final Drive - Each | 25 l (7 gal US) |
| Cooling System | 126 l (33 gal US) |
| Hydraulic Reservoir | 190 l (50 gal US) |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
633B fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| engine crankcase (with filter) | CAT DEO SAE 15W-40; SAE 10W-30 for cold weather; SAE 0W-40 for extreme cold weather | |
| cooling system | ||
| fuel tank | ||
| hydraulic system and tank | Cat HYDO Advanced | |
| grease | CAT Multipurpose Grease for low-load/low-speed; CAT Advanced 3Moly Grease for medium-load/medium-speed; CAT Ultra 5Moly Grease for high-load/high-speed |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar 633B maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
Servicing the 633B beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize Caterpillar S.O.S Services to monitor the 633B's health. Regularly analyze engine oil for wear metals like iron or copper, and check hydraulic fluid for particle counts and oxidation. Monitoring coolant pH and SCA levels prevents internal liner pitting. Early detection of silicon in engine oil can signal air intake leaks before catastrophic failure occurs. Use these samples to extend drain intervals safely under normal operating conditions.
Corrective & Common Repairs
Address hydraulic system failures by inspecting return filters for contamination, as debris causes most pump and valve damage. Monitor the 633B's electrical systems for instability, which often stems from harness abrasion or loose connections near vibrating components. If engine power decreases, inspect the electronic fuel injection system and injector flow. Ensure all hydraulic hoses are checked for cracks or swelling to prevent high-pressure leaks during heavy loading cycles.
Overhaul & Rebuild Points
Plan major interventions when structural inspections reveal weld fatigue in the boom or scraper frame. During 2,000-hour intervals, evaluate the condition of the transmission and final drives for gear wear. Significant engine rebuilds are often necessitated by prolonged operation with contaminated oil, leading to piston or bearing damage. Comprehensive component evaluation should include measuring play in articulation joints and checking the integrity of the turbocharger assembly.
Seasonal & Environment Servicing
In dusty or quarry environments, shorten air filter inspection intervals and clean radiator fins daily to prevent overheating. For machines operating in cold climates, utilize appropriate Arctic grease and low-temperature engine oils. In high-moisture or saltwater areas, pay extra attention to battery terminal corrosion and chassis integrity. Always adjust service schedules based on the specific duty cycle and local environmental stressors to protect the 633B's powertrain.
633B fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| 110-0 | Engine Coolant Temperature — Above Normal | Low coolant level or thermostat failure | Inspect cooling system, refill coolant, and test thermostat |
| 110-3 | Engine Coolant Temp Sensor — Voltage High | Open circuit or sensor failure | Check wiring harness and replace sensor if confirmed faulty |
| 174-3 | Engine Fuel Temperature — Voltage Above Normal | Open circuit in sensor wiring | Inspect fuel temperature sensor 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 and 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 |
| E360 | Engine Coolant Temperature — High | Low coolant, failed thermostat, or water pump issue | Diagnose cooling system; do not operate until resolved |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
633B attachments & work tools
Scraper Configurations
Available arrangements include single-engine and tandem-engine open bowls, tandem engine push-pulls, elevators, and auger arrangements.
Work Tool Families
Primary configurations consist of open bowl, elevating flight, and coal auger scrapers. The 633B class specifically supports the 86H scraper configuration.
Mounting & Attachments
Standard and optional attachments are available for this machine class. Scraper-mounted fuel tanks may be used to improve access to the tractor engine compartment.
Hydraulic & Technology Systems
Optional Cat Grade technology and Product Link™ data collection systems can be integrated. Hydraulic systems should utilize Cat HYDO Advanced oils or Bio HYDO Advanced for environmental compliance.
Protection & Guarding
Laminated thermal shields are available to reduce engine surface temperatures, protect exposed surfaces, and extend the life of hoses and wiring.
All 633B assemblies by section
Every catalogued assembly group for the Caterpillar 633B. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
633 Elevating Scraper
7j7230 Air Control Valve Group
| 7J***30 | Air Control Valve Group | 1 |
Bowl--As Viewed From Rear Right Hand Side Of Scraper
6m7308 Bowl Check Valve Group
| 6M***08 | Bowl Check Valve Group | 1 |
7j243 Bowl Lift Cylinder Group--7.25" Bore X 25.00" Stroke--2 Required
| 7J***43 | Bowl Lift Cylinder Group | 1 |
5j7654 Bowl Lift Cylinder Group--7.25" Bore X 25.00" Stroke--2 Required
| 5J***54 | Bowl Lift Cylinder Group | 1 |
Brake Control (5j9529 N/S)--As Viewed From Rear Right Hand Side Of Scraper
| 5J***29 | Brake Control | 1 |
Brakes (6j425 N/S)
| 6J***25 | Brakes | 1 |
7j2174 Chain Adjuster Cylinder Group
| 7J***74 | Chain Adjuster Cylinder Group | 1 |
Chain And Flight (5j9428 N/S)
| 5J***28 | Chain And Flight | 1 |
7j7328 Control Valve Group
| 7J***28 | Control Valve Group | 1 |
7j4776 Cushion And Roller Support Group--Field Installation
| 7J***76 | Cushion And Roller Support Group | 1 |
7j4777 Cushion Support Group--Field Installation
| 7J***77 | Cushion Support Group | 1 |
8j1599 Chain Adjuster Cylinder Group--3.00" Bore X 5.12" Stroke
| 8J***99 | Cylinder Group | 1 |
7j1693 Hydraulic Cylinder Group--R.H.--6.5" Bore X 33.00" Stroke
| 7J***93 | Cylinder Group-Hydraulic | 1 |
Draft Frame (5j7756 N/S)--As Viewed From Front Left Hand Side Of Scraper
| 5J***56 | Draft Frame | 1 |
Draft Frame (5j7756 N/S)--As Viewed From Front Left Hand Side Of Scraper--Type 2
| 5J***56 | Draft Frame | 1 |
Draft Frame (5j7756 N/S)--As Viewed From Front Left Hand Side Of Scraper--Type 1
| 5J***56 | Draft Frame | 1 |
Draft Frame Lines (5j9531 N/S)--As Viewed From Right Hand Side Of Scraper--Part 1 Of 3
| 5J***31 | Draft Frame Lines | 1 |
Draft Frame Lines (5j9531 N/S)--As Viewed From Right Hand Side Of Scraper--Part 3 Of 3
| 5J***31 | Draft Frame Lines | 1 |
Draft Frame Lines (5j9531 N/S)--As Viewed From Right Hand Side Of Scraper-Part 2 Of 4
| 5J***31 | Draft Frame Lines | 1 |
Draft Frame Lines (5j9531 N/S)--As Viewed From Right Hand Side Of Scraper--Part 3 Of 4
| 5J***31 | Draft Frame Lines | 1 |
Draft Frame Lines (5j9531 N/S)--As Viewed From Right Hand Side Of Scraper--Part 2 Of 4
| 5J***31 | Draft Frame Lines | 1 |
Draft Frame Lines (5j9531 N/S)--As Viewed From Right Hand Side Of Scraper--Part 2 Of 3
| 5J***31 | Draft Frame Lines | 1 |
Draft Frame Lines (5j9531 N/S)--As Viewed From Right Hand Side Of Scraper--Part 4 Of 4
| 5J***31 | Draft Frame Lines | 1 |
Draft Frame Lines (5j9531 N & S)--As Viewed From Right Hand Side Of Scraper--Part 1 Of 4
| 5J***31 | Draft Frame Lines | 1 |
Draft Frame Lines (5j9531 N/S)--As Viewed From Right Hand Side Of Scraper--Part 1 Of 4
| 5J***31 | Draft Frame Lines | 1 |
6j306 Ejector Check Valve Group
| 6J***06 | Ejector Check Valve Group | 1 |
5j9285 Ejector Floor Group
| 5J***85 | Ejector Floor | 1 |
7j4980 Ejector Floor Group--Field Installation
| 7J***80 | Ejector Floor Group | 1 |
Ejector Lines (5j9481 N/S)--As Viewed From Right Hand Side Of Scraper
| 5J***81 | Ejector Lines | 1 |
Elevator Drive (5j9257 N/S)
| 5J***57 | Elevator Drive | 1 |
Elevator Frame (6m4918 N/S)--As Viewed From Front R.H. Side Of Scraper--Part 1 Of 2
| 6M***18 | Elevator Frame | 1 |
Elevator Frame (6m4918 N/S)--As Viewed From Front R.H. Side Of Scraper--Part 2 Of 2
| 6M***18 | Elevator Frame | 1 |
8j4076 Elevator Group--Part 1 Of 2--Type 2--Field Installation
| 8J***76 | Elevator Group | 1 |
8j4076 Elevator Group--Part 2 Of 2--Type 1--Field Installation
| 8J***76 | Elevator Group | 1 |
8j4076 Elevator Group--Part 2 Of 2--Type 2--Field Installation
| 8J***76 | Elevator Group | 1 |
8j4076 Elevator Group--Part 1 Of 2--Type 1--Field Installation
| 8J***76 | Elevator Group | 1 |
Elevator Guard (6j1737 N/S)
| 6J***37 | Elevator Guard | 1 |
Elevator Linkage (5j9362 N/S)
| 5J***62 | Elevator Linkage Group | 1 |
7j7955 Elevator Reversing Control Group
| 7J***55 | Elevator Reversing Control Group | 1 |
7j7448 Elevator Reversing Group
| 7J***48 | Elevator Reversing Group | 1 |
7j8511 Elevator Reversing Mechanism--Field Installation
| 7J***48 | Elevator Reversing Group | 1 |
| 7J***55 | Elevator Reversing Control Group | 1 |
| 7J***11 | Elevator Reversing Mechanism | 1 |
6j6898 Fender Group
| 6J***98 | Fender Group | 1 |
7j4160 Floor Cleaner Group
| 7J***60 | Floor Cleaner Group | 1 |
Floor Control Lines (5j9532 N/S)
| 5J***32 | Floor Control Lines | 1 |
Ejector Lift Frame (5j8880 N/S)
| 5J***80 | Frame Group-Lift | 1 |
3g464 Hose Assembly
| 3G***64 | Hose As | 1 |
| 3S***52 | Sleeve) | 2 |
| 3S***96 | Stem Assem. ('Straight) | 1 |
7j2648 Hydraulic Chain Adjuster Group--Field Installation--Type 1
| 7J***48 | Hydraulic Chain Adjuster Group | 1 |
7j2648 Hydraulic Chain Adjuster Group--Field Installation--Type 2
| 7J***48 | Hydraulic Chain Adjuster Group | 1 |
6j341 Hydraulic Motor Assembly
| 6J***41 | Hydraulic Motor Assembly | 1 |
5j3642 Hydraulic Swivel Joint Group
| 5J***42 | Hydraulic Swivel Joint Group | 1 |
6j230 Hydraulic Swivel Joint Group--Type 2
| 6J***30 | Hydraulic Swivel Joint Group | 1 |
6j230 Hydraulic Swivel Joint Group--Type 1
| 6J***30 | Hydraulic Swivel Joint Group | 1 |
Motor Lines (5j9530 N/S)--As Viewed From Right Hand Side Of Machine
| 5J***30 | Motor Lines | 1 |
Name Plates And Transfers
| 1S***93 | Plate- Scraper Capacity | 1 |
| 2M***31 | Plate; Serial Number On R.H. Side Of Cylinder Block And R.H. Side Of Loader Frame | 1 |
| 4B***58 | Screw (Identification Plate) Mounting | 14 |
7j8202 Pilot Valve Group
| 7J***02 | Pilot Valve Group | 1 |
5s979 Planetary Reduction Gear Group
| 5S***79 | Planetary Reduction Gear Group | 1 |
3j4887 Relay Valve Assembly
| 3J***87 | Relay Valve Assembly | 1 |
3d2744 Rotochamber Assembly
| 3D***44 | Rotochamber | 1 |
6d6355 Brake Shield Group
| 6D***55 | Shield Group-Brake | 1 |
6j3692 Skid Plate Group
| 6J***92 | Skid Plate Group | 1 |
5d5749 Slack Adjuster Assembly
| 5D***49 | Slack Adjuster Group | 1 |
6j9166 Sprocket Idler Group
| 6J***66 | Sprocket Idler Group | 1 |
5j7615 Sprocket Idler Group
| 5J***15 | Sprocket Idler Group | 1 |
5j7806 Hydraulic Cylinder Group--6.5" Bore X 33.00" Stroke--2 Required
| 5J***06 | Steering Cylinder Group | 1 |
5j9256 Support Group
| 5J***56 | Support Group | 1 |
8j6406 Tooth Group
| 8J***06 | Tooth Group | 1 |
6j4482 Tooth Group
| 6J***82 | Tooth Group | 1 |
7j3195 Tooth Group
| 7J***95 | Tooth Group | 1 |
5j9575 Travel Bracket Group
| 5J***75 | Travel Bracket Group | 1 |
4j8500 Control Valve Assembly
| 4J***00 | Valve As-Control | 1 |
5j4615 Relief Valve Group
| 5J***15 | Valve Group-Relief | 1 |
6j424 Wheel And Axle Group--33.25 X 35 Tubeless Tires
| 6J***24 | Wheel And Axle | 1 |
633B serial number reference
Locate the ID plate on the machine outer frame. The serial number prefix consists of the first three alphanumeric characters of the Product Identification Number (PIN). For pre-2002 models, the serial number is an 8-character alphanumeric code; for post-2001 models, it is the last 8 characters of the 17-character PIN.
| Prefix | Identifies | Notes |
|---|---|---|
| 86H | 633B Wheel Scraper | Serial prefix 86H identifies the 633B configuration. Note that this prefix is also associated with the 633 (pre-B) model in some parts catalogs; verify the specific model designation on the machine ID plate to distinguish between 633 and 633B. |
Frequently asked questions
What engine powers the Caterpillar 633B?
The 633B utilizes a Caterpillar engine configuration, with specific models in this series often featuring the 3408E engine providing approximately 270 HP (202 kW) at 2000 rpm.
What is the operating weight of the machine?
The operating weight varies by configuration and serial range; however, related heavy-class Caterpillar earthmoving machines typically fall within a broad range of 9,182 lb (4,165 kg) to 87,083 lb (39,500 kg).
What machine replaced the 633B?
The 633B is part of a lineage of Caterpillar scrapers that includes the 633E and 633E II series, which introduced further advancements in elevator drive and hydraulic performance.
What 633B owners discuss
What are common hydraulic performance issues observed in Caterpillar scrapers?
What engine-related power loss symptoms should be monitored?
What electrical issues frequently affect Caterpillar machine operation?
What are the typical wear patterns for heavy-duty drive components?
What should be checked regarding the electrical harness during troubleshooting?
What is the most critical item to check when purchasing a used 633B scraper?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific 633B part?
Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.