Caterpillar 825C
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar 825C is a heavy-duty earthmoving soil compactor designed for high-production roadwork and construction applications. This machine features a 3406 engine with 14.6 L displacement, delivering approximately 234.9 kW (315 hp) of gross power. The configuration utilizes a four-gear transmission system with four forward and four reverse gears. With an operating weight of approximately 32,400 kg (71,429 lb), the 825C is engineered for significant compaction force across its roller drums.
Across different series, Caterpillar has evolved the compactor line from the 825C toward more modern iterations like the 825K, which utilizes advanced Machine Drive Power (MDP) systems and higher horsepower engines. The 825C remains a critical asset in the used parts and machinery market due to its robust 3406 engine architecture and heavy-duty chassis. Its durability makes it a primary candidate for component rebuilding, particularly regarding transmission, hydraulic pumps, and final drives.
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 825C specifications
Engine
| Model | 3406 |
| Gross Power | 315 hp (234.9 kW) |
| Displacement | 891 cu in (14.6 L) |
Weights
| Operating Weight | 71,429.8 lb (32,400 kg) |
Dimensions
| Length With Blade On Ground | 25.23 ft in (7690 mm) |
| Width Over Wheels | 11.98 ft in (3650 mm) |
| Height To Top Of Cab | 12.83 ft in (3910 mm) |
| Wheelbase | 11.59 ft in (3530 mm) |
| Ground Clearance | 0.77 ft in (234 mm) |
Performance
| Forward Gears | 4 |
| Reverse Gears | 4 |
| Front Wheels Drum Diameter | 50.8 in (1290 mm) |
| Rear Wheels Drum Diameter | 50.8 in (1290 mm) |
| Front Wheels Drum Width | 44.1 in (1118 mm) |
| Rear Wheels Drum Width | 44.1 in (1118 mm) |
| Blade Height | 41 in (1040 mm) |
| Blade Width | 14.9 ft in (4530 mm) |
Service capacities (summary)
| Fuel Capacity | 155.6 gal (589 L) |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
825C fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with filter) | Not specified | Cat DEO or DEO-ULS |
| Cooling system | Not specified | Cat ELC |
| Fuel tank | 589 l (155.6 gal) | Not specified |
| Transmission/powertrain compartments | Not specified | Cat TDTO |
| Hydraulic system and tank | Not specified | Cat HYDO Advanced |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar 825C maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
Servicing the 825C beyond the schedule
Predictive Maintenance & Fluid Analysis
Utilize Caterpillar S.O.S Services to monitor the health of the 3406 engine and hydraulic systems. Regularly analyze engine oil for wear metals like iron or copper, and check hydraulic fluid for particle counts and water content. Monitoring coolant via Level 2 analysis can prevent internal liner pitting. Use Cat HYDO Advanced oils to extend drain intervals and protect against cavitation in high-load compaction cycles.
Corrective & Common Repairs
Frequent repair focus on the hydraulic system, specifically replacing hydraulic return filters to prevent pump damage from contamination. Monitor steering cylinders for leaks and inspect pins and bushings for excessive play. If milky oil is observed on the dipstick, immediately investigate potential head gasket failure or coolant contamination. Ensure all solenoid valves are checked for electrical continuity during hydraulic troubleshooting.
Overhaul & Rebuild Points
Major service milestones include a full transmission service and hydraulic oil change at the 2,000-hour mark. During major component evaluations, inspect the turbocharger and final drive gears for fatigue. For high-hour machines, evaluate the structural integrity of the chassis and the condition of the 3406 engine's internal components. Rebuilding critical systems like the differential or steering gear is essential for maintaining machine availability.
Seasonal & Environment Servicing
In dusty or quarry environments, shorten air filter inspection intervals to daily and replace elements more frequently. Clean radiator and oil cooler fins daily to prevent overheating. For machines operating in extreme temperatures, verify the integrity of all hoses and belts to prevent cracking or failure. Ensure fuel quality is high and water separators are drained regularly to prevent fuel system degradation during seasonal transitions.
825C common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 8T-6765 | Plug-Pipe | Scheduled service item | Check fitment → |
| 9S-8752 | Nut-Full | Scheduled service item | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
825C 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 and refill coolant |
| 110-3 | Engine Coolant Temp Sensor — Voltage High | Open circuit or sensor failure | Check wiring and replace sensor if faulty |
| 174-3 | Engine Fuel Temperature — Voltage Above Normal | Open circuit in sensor wiring | Inspect harness and replace sensor if necessary |
| 190-8 | Engine Speed — Abnormal Frequency | Speed sensor air gap, sensor failure, or tone ring damage | Check sensor gap and test speed sensor/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.
825C attachments & work tools
Blades
Standard configuration includes a moldboard with 14.9 ft (4.54 m) width and 41 in (1.04 m) height. The blade is used for spreading fill to reduce the need for spreader tractors.
Drum Configuration
Equipped with front and rear drums, each measuring 50.8 in (1.29 m) in diameter and 44.1 in (1.12 m) in width. The configuration provides a width over drums of 11.98 ft (3.65 m).
Hydraulic System
The machine utilizes a hydraulic system for various functions, including steering and blade operation. Specific solenoid valve arrangements are used within the hydraulic system architecture.
All 825C assemblies by section
Every catalogued assembly group for the Caterpillar 825C. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Basic Engine
304-6674 Kit-Hardware
| 03***19 | Bolt; --To Bearing Ret. At Lower Front Shaft Bore | 11 |
| 0L***70 | Bolt (2-1/4") Filler Tube Assembly To Transfer Drive Case | 1 |
| 0S***71 | Screw,Cap,Hexagon; Tube Assembly To Turbocharger And Elbow Mounting | 3 |
308-2942 Kit-Hardware
| 0S***94 | Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly | 2 |
| 0T***65 | Bolt--3/8" X 3 1/2"--Use As Required; Bolt 5t***56 Plate To Cover Gp 4n***72 | 8 |
| 11***87 | Seal-O-Ring (23.16 mm Id) | 1 |
Engine Arrangement
308-7318 Conversion Ar-Engine
| 03***79 | Seal-O-Ring (Id=10.82mm) | 1 |
| 0R***80 | Rod As-Connecting | 1 |
| 0R***87 | Camshaft As | 1 |
309-4515 Conversion Ar-Engine
| 03***79 | Seal-O-Ring (Id=10.82mm) | 1 |
| 0R***80 | Rod As-Connecting | 1 |
| 0R***87 | Camshaft As | 1 |
Fuel System
9y-1234 Fastener Gp-Fuel Inj Pump -Governor
| 1B***16 | Bolt; (1/4-20x5-In) | 2 |
| 4F***57 | Screw,Cap,Hexagon H Shock Mount To Bracket | 2 |
| 5B***40 | Bolt; (1/4-20x1-In) | 2 |
7c-4797 Governor Gp
| 03***16 | Bolt-Self Locking; (1/4unc X 3/4) | 3 |
| 0S***47 | Bolt; (1/4-20x0.75-In)(Drilled Head) | 2 |
| 0S***88 | Bolt,Machine; Hose Assembly Mounting,Hose Assembly To Transmission,And To Torque Converter | 1 |
104-4409 Pump Gp-Fuel Injection
| 0S***15 | Bolt 19 mm (.75 In.) Long Return Air Console To Enclosed Rops | 14 |
| 10***09 | Pump Group-Fuel Injection | 1 |
| 10***52 | Camshaft-Fuel Pump | 1 |
108-6633 Pump Gp-Fuel Injection
| 10***02 | Bonnet-Valve | 1 |
| 10***04 | Plunger & Barrel As | 1 |
| 10***33 | Pump Group-Fuel Injection | 1 |
2w-8628 Torque Control Gp
| 1P***52 | Insulator,Bushing Governor | 1 |
| 2P***85 | Spacer (.635 mm Thk); (0.635-mm Thk) | 1 |
| 2W***34 | Bar-Load Stop; (4.0mm Thk) | 1 |
Service Equipment And Supplies
308-7319 Kit-Engine Parts
| 06***40 | Seal-O-Ring (Id=37.69mm) | 1 |
| 10***48 | Ring-Guide | 1 |
| 10***49 | Plate | 1 |
308-7320 Kit-Engine Parts
| 06***40 | Seal-O-Ring (Id=37.69mm) | 1 |
| 10***48 | Ring-Guide | 1 |
| 10***49 | Plate | 1 |
309-4516 Kit-Engine Parts
| 03***46 | Elbow, 90 Deg Adj., 1/4in. J.I.C. X 7/16in.-14 Str. Thd. | 1 |
| 06***40 | Seal-O-Ring (Id=37.69mm) | 1 |
| 10***48 | Ring-Guide | 1 |
Frequently asked questions
What engine powers the Caterpillar 825C?
The Caterpillar 825C is equipped with a Caterpillar 3406 engine featuring a 14.6 L displacement.
What is the standard operating weight of this machine?
The standard operating weight for the 825C compactor is approximately 32,400 kg (71,429 lb).
What model replaced the 825C in the Caterpillar lineup?
While specific direct-successor lineage varies by region, the 825K represents a modern evolution of the heavy soil compactor class.
What 825C owners discuss
What engine is typically installed in the Caterpillar 825C?
What are the common electrical failure points for Caterpillar heavy machinery?
What are the primary indicators of hydraulic system degradation in these machines?
What engine-related performance issues should be monitored during operation?
What are the typical dimensions and weight for a standard 825C?
What should be checked when inspecting a used 825C for purchase?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific 825C part?
Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.