Caterpillar D30C
Caterpillararticulated dump truckarticulated truck

Caterpillar D30C

Maintenance schedule, common problems & OEM parts breakdown

Search live D30C parts

The Caterpillar D30C is a two-axle articulated dump truck built from 1986 to 1989 as part of Cat's early C-series articulated hauler line, alongside the D25C, D35C, and D350C. It runs the Caterpillar 3306TA, a mechanically governed, turbocharged inline-six diesel of about 10.5 liters displacement rated near 194 kW (260 hp) gross, using jerk-pump fuel injection with no electronic engine control. Operating weight is roughly 21.3 tonnes (47,000 lb) empty, with a rated payload near 27.2 tonnes and a heaped dump body capacity around 17 m3, giving it a top travel speed near 56 km/h (35 mph). Cat offered the D30C in a standard rock-body configuration as its roughly 30-ton-class entry, built during the period Cat was establishing its own articulated truck family with Cat-sourced engines and drivetrains.

Across the C-series family the D25C through D350C shared the same mechanical 3306 fuel system and hydraulically actuated articulation and steering circuit, differing mainly in frame length, axle rating, and body size. Caterpillar replaced the D30C with the D30D starting in 1989, and the D-series ran into the early 2000s before being succeeded by Cat's modern 700-range haulers. Because the D30C uses purely mechanical governing with no ECM or fault-code system, it still draws interest from buyers who want a haul truck without electronic diagnostics to service or troubleshoot. Used values now trade mainly on drivetrain condition and structural integrity of the frame, articulation joint, and dump body, since these mechanical wear points -- not electronics -- determine remaining service life on a machine this old.

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 D30C specifications

Engine

Production seriesBuilt 1986-1989, part of the C-series articulated truck line alongside the D25C, D35C and D350C, sharing a common chassis and driveline family
Engine modelCaterpillar 3306TA, turbocharged inline 6-cylinder diesel
Gross power194 kW (260 hp)
Displacement10.5 L (638 cu in)
Cylinders6, inline
Emissions tierPredates EPA/EU nonroad emissions tier regulation (built before the mid-1990s tier framework existed)

Weights

Operating weight21.3 t (47,000 lb)
Rated payload / net load27.2 t (approx. 60,000 lb)
Ground pressureNot published in available spec sources for this model

Dimensions

Transport length8.86-9.77 m (29 ft 1 in - 32 ft), varies by source/configuration
Transport width3.30-3.36 m (10 ft 10 in - 11 ft), varies by source
Transport height3.33 m (10 ft 11 in)
Dump/loading height2.85 m (9 ft 4 in)
Wheelbase / ground clearanceNot published in available spec sources for this model

Performance

Travel speed56 km/h (34.8 mph), top forward gear
GradeabilityNot published in available spec sources for this model
Dump body capacityApprox. 17 m³ heaped

Service capacities (summary)

Fuel tank, hydraulic, engine oil, cooling systemNot documented in available spec sources for this exact series — verify with your dealer or the D25C/D30C/D35C/D350C operation and maintenance manual

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

D30C fluids & capacities

SystemCapacityRecommended fluid
Engine crankcase (with filter)Not documented in publicly accessible sources for this exact model/serial range — confirm against the machine's OMM or with a Cat dealerCat DEO (Diesel Engine Oil); grade selected by ambient temperature per the standard Cat multigrade chart for this engine class (commonly 15W-40 in temperate ranges, lighter 10W-30 grade in cold climates)
Cooling systemNot documented in publicly accessible sources for this exact model/serial range — confirm against the machine's OMM or with a Cat dealerCat ELC (Extended Life Coolant) or Cat DEAC (Diesel Engine Antifreeze/Coolant), mixed to the standard 50/50 water ratio; heavier antifreeze concentration for sub-freezing climates per the OMM's climate table
Fuel tankNot documented in publicly accessible sources for this exact model/serial range — confirm against the machine's OMM or with a Cat dealerNo. 2-D diesel fuel as the general-duty grade; No. 1-D or a winter-blend diesel in cold-climate operation per the OMM's fuel recommendation table
Powershift transmissionNot documented in publicly accessible sources for this exact model/serial range — confirm against the machine's OMM or with a Cat dealerCat TDTO (Transmission/Drive Train Oil); viscosity grade selected by ambient temperature per the OMM's climate table
Front final drive / axle housingNot documented in publicly accessible sources for this exact model/serial range — confirm against the machine's OMM or with a Cat dealerCat TDTO (Transmission/Drive Train Oil), viscosity by ambient temperature
Rear final drives / axle housings (each)Not documented in publicly accessible sources for this exact model/serial range — confirm against the machine's OMM or with a Cat dealerCat TDTO (Transmission/Drive Train Oil), viscosity by ambient temperature
Hydraulic system and tankNot documented in publicly accessible sources for this exact model/serial range — confirm against the machine's OMM or with a Cat dealerCat TDTO or Cat HYDO hydraulic oil (grade depends on the machine's specific hydraulic circuit design); viscosity by ambient temperature per the OMM's climate table
Grease points (pins, bushings, articulation joint)Spec only — no fill volume applicableCat Multipurpose grease (moly-based EP grease for high-load pin and bushing joints, including the articulation hitch)

Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.

Caterpillar D30C maintenance schedule

Service intervalTasks
Every 10 h
  • Check engine oil level before starting and top off with the correct Cat DEO-class oil
  • Check coolant level in the radiator or expansion tank
  • Drain water and sediment from the fuel tank water separator
  • Walk-around inspection of the articulation joint and steering cylinder pins for leaks or looseness
  • Check tire condition and inflation pressure
  • Grease articulation hitch and steering cylinder pivot points weekly
Every 250 h
  • Change engine oil and filter
  • Inspect and clean the primary fuel filter and water separator element
  • Check transmission oil level and look for signs of contamination
  • Check final drive oil level at each wheel
  • Check hydraulic tank oil level and inspect steering and hoist cylinders for leaks
  • Lubricate all articulation, steering cylinder, and hoist cylinder grease fittings
Every 500 h
  • Replace fuel filter elements
  • Change the transmission oil filter and check oil condition
  • Pull oil samples from engine, transmission, final drives, and hydraulic system for lab analysis
  • Inspect the turbocharger for shaft play and boost leaks
  • Check and adjust fan and alternator belt tension
  • Inspect the brake system for wear and hydraulic leaks
Every 1,000 h
  • Change transmission oil
  • Change final drive oil at each wheel end
  • Change hydraulic system oil and filter
  • Adjust engine valve lash on the mechanically governed 3306
  • Inspect and adjust the fuel injection governor linkage
  • Inspect differential and axle housings for oil level and condition
Every 2,000 h
  • Change engine coolant and inspect the cooling system and aftercooler for leaks
  • Inspect wet brake discs for wear and contamination
  • Measure center articulation joint bearing and pin bore wear
  • Check and adjust wheel bearing preload
  • Inspect the frame and dump body for cracks and structural wear
  • Inspect hoist cylinder mounts and pivot pins for wear
Every 4,000 h
  • Overhaul or recalibrate the fuel injection pump and injectors
  • Replace the turbocharger cartridge once shaft play exceeds spec
  • Inspect and rebuild transmission clutch packs and the torque converter
  • Replace articulation joint bushings and bearings
  • Inspect final drive planetary gear sets for wear

Servicing the D30C beyond the schedule

Predictive Maintenance & Fluid Analysis

The D30C has no ECM or fault codes, so condition-based upkeep leans on scheduled oil sampling. Pull engine, transmission, final drive, and hydraulic oil samples at set intervals and send them for lab analysis, watching for fuel dilution from worn jerk-pump plungers, coolant intrusion pointing to a failing aftercooler, and metal particles in the final drive housings that signal gear wear before it becomes an audible failure. Track turbocharger boost and shaft play trends by hand, since this era 3306 has no onboard diagnostics.

Corrective & Common Repairs

Typical D30C repairs center on the mechanical fuel system: sticking jerk-pump plungers, worn governor linkage, and injector nozzle wear that show up as rough idle or lost power. Turbocharger shaft seal leaks and boost loss are common on the 3306TA. Steering and hoist cylinder seals wear out after years of dust ingress at the articulation joint. Wet-type final drive and differential seals often need attention at higher hours. Inspect dump body pivot pins and hoist cylinder mounts for wear from repeated quarry-duty cycling.

Overhaul & Rebuild Points

Major rebuild work on the D30C follows its mechanical powertrain. Full fuel injection pump and injector calibration restores power and fuel economy lost to plunger wear. Turbocharger cartridge replacement is standard once shaft play exceeds spec. Transmission clutch packs and the torque converter wear from constant load-and-haul cycling. The center articulation joint bearing and pin bores wear from steering and frame-twist loads and need periodic measurement and bushing replacement. Final drive planetary gear sets and wet brake discs are the other high-wear items to check at major overhaul.

Seasonal & Environment Servicing

In cold climates, use a block heater and correct-viscosity engine oil before cold starts, since the mechanically governed 3306 has no ECM-assisted cold-start strategy beyond ether injection. Drain the fuel tank water separator often in wet or humid conditions to protect the jerk pumps from water-induced scoring. In dusty quarry or mine environments, service air cleaner elements more frequently and check the turbocharger inlet for dust bypass. Wash accumulated mud from the articulation joint and hoist linkage regularly so grease fittings don't pack with abrasive grit.

D30C common service parts

Part numberPart
8M-3182Spring,Helical,Comp Engine Oil Filter AssemblyCheck fitment →
2P-2537Stud Engine Oil FilterCheck fitment →

Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.

D30C attachments & work tools

Dump body

Standard factory body on this class is a V-shaped/dual-slope steel dump body for low center of gravity and even load distribution. Site-specific liner packages (bolt-in wear liners) are offered for abrasive or sharp-edged material to protect the base body.

Tailgate

Tailgate is an optional fitment rather than fixed equipment on this size class; running without a tailgate cuts tare weight and maintenance but reduces retained payload for fine or free-flowing material. Choice depends on material type hauled at the site.

Differential lock

Front and rear differential lock, engaged from the cab, is offered for traction in soft, muddy, or loose underfoot conditions typical of articulated-hauler duty cycles. Standard traction aid across this size/era of Cat articulated truck.

ROPS/FOPS cab structure

Cab is built around an integral ROPS (Roll Over Protective Structure) and FOPS (Falling Object Protective Structure) frame rather than a bolt-on canopy kit, giving rollover and falling-object protection as a factory structural feature.

Tires

Off-highway bias or radial tires in roughly the 29.5-25 class are typical for this 30-tonne-class articulated hauler; exact size and ply/radial choice varies by configuration and dealer-fitted option, so confirm against the data plate.

Engine arrangement

Powered by the Cat 3306 inline-six diesel, offered across this size class in naturally aspirated and turbocharged arrangements with rated output varying by arrangement; confirm the fitted arrangement from the engine serial/arrangement number rather than assuming one output figure.

Mud flaps and fenders

Rear mud flaps/fenders are a common dealer-fitted accessory on this class to control debris and spray thrown from the drive tires on haul roads; not part of every base configuration.

Chassis lubrication

A centralized manual or automatic grease-bank lubrication option is commonly offered on this size/era of articulated hauler to service articulation joint, hoist pins, and axle pivot points; availability and routing vary by dealer-installed kit rather than one fixed factory spec.

All D30C assemblies by section

Every catalogued assembly group for the Caterpillar D30C. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Basic Engine
284-7811 Kit-Hardware
0L***43Bolt 63.5 mm (3/8" X 2 1/2" -Cover Assembly To Fender1
0S***91Screw,Cap,Hexagon Bearing Retainer; Part Of Kit P/N 1w***822
0S***94Bolt (1 In. Long 3/8 In. Dia.); Plate Assembly To Support Assembly2
See all parts with full part numbers in Heavy Parts AI →
Engine Arrangement
284-3287 Conversion Ar-Engine
0R***14Rod As-Connecting1
0R***97Cylinder Pack Group6
0R***82Injector As6
See all parts with full part numbers in Heavy Parts AI →
Fuel System
7c-8993 Fastener Gp-Fuel Inj Pump
0S***14Bolt (.25" Diameter-.50" Long)3
2S***83Bolt (3.25" Long-Drilled Head)1
4F***57Screw,Cap,Hexagon H Shock Mount To Bracket8
See all parts with full part numbers in Heavy Parts AI →
111-5162 Control Gp-Fuel Ratio
10***93Washer1
11***62Control Group-Fuel Ratio (Basic)1
11***58Washer; (12.7x6.65x0.79-mm Thk)1
See all parts with full part numbers in Heavy Parts AI →
2w-2410 Governor Gp
03***16Bolt-Self Locking; (1/4unc X 3/4)3
0S***16Screw,Cap,Hexagon H Receptacle Mtg; Bolt Brackets To Firewall Assembly6
13***07Seal-Lip Type; (6.39mm)1
See all parts with full part numbers in Heavy Parts AI →
115-9595 Pump Gp-Fuel Injection
0S***15Bolt 19 mm (.75 In.) Long Return Air Console To Enclosed Rops4
11***18Seal-O-Ring; (26.64mm Id)6
11***95Pump Group-Fuel Injection1
See all parts with full part numbers in Heavy Parts AI →
4p-9827 Pump Gp-Fuel Injection
1W***87Valve As-Check; (Fuel Injection Pump)1
4P***27Pump Group-Fuel Injection1
4P***30Plunger & Barrel Assem.1
See all parts with full part numbers in Heavy Parts AI →
7c-8992 Seal Gp-Pump
03***79Seal-O-Ring (Id=10.82mm)1
14***77Gasket1
15***26Gasket1
See all parts with full part numbers in Heavy Parts AI →
1w-1597 Torque Control Gp
1P***52Insulator,Bushing Governor1
1W***97Torque Control Group1
2P***85Spacer (.635 mm Thk); (0.635-mm Thk)1
See all parts with full part numbers in Heavy Parts AI →
Service Equipment And Supplies
284-3299 Kit-Engine Parts
10***68Hose As1
10***69Tube As; (Oil)1
12***74Clip-Loop; (12.7mm Id)1
See all parts with full part numbers in Heavy Parts AI →

D30C serial number reference

The PIN plate on a D30C sits on the front frame section near the articulation joint, low on the left side on most articulated-truck-era Cat plates (some early-1980s units carry it higher on the right). It is a riveted metal tag stamped with the full Product ID Number; the first three characters are the letter/number serial prefix, and the digits after it are the sequential unit number. Clean off grease and use a flashlight to read it, since decades of buildup commonly obscure the stamping.

PrefixIdentifies
7ZCD30C articulated dump truck, base/only documented series

Frequently asked questions

What engine does the Caterpillar D30C use?

The D30C is powered by the Caterpillar 3306TA, a mechanically governed turbocharged inline-six diesel of about 10.5 liters displacement rated near 194 kW (260 hp) gross. It uses jerk-pump fuel injection and predates Cat's electronic engine management, so there is no ECM or fault-code system on this engine.

What is the operating weight of the Caterpillar D30C?

The D30C's operating weight is about 21.3 tonnes (47,000 lb) empty, with a rated payload near 27.2 tonnes, placing it in Caterpillar's roughly 30-ton-class articulated truck bracket alongside its D25C and D35C siblings.

What replaced the Caterpillar D30C?

Caterpillar replaced the D30C with the D30D starting in 1989. The D30D ran through 2001, after which Caterpillar's D-series articulated trucks gave way to the modern 700-range haulers such as the 725 and 730.

What D30C owners discuss

What is the D30C's transmission and torque converter like in daily operation?
The D30C runs a mechanical torque-converter powershift transmission, not the electronically modulated units fitted to later D-series haulers. Once oil temperature comes up it shifts firmly and predictably. On a cold start, thick converter oil can cause a soft, delayed upshift or a brief flare before things settle down, and that's considered normal warm-up behavior, not a fault. Persistent slipping, a converter that stays hot after warm-up, or delayed engagement in gear point to worn clutch packs or a charging pump losing output rather than any control module, since there isn't one on this machine. Have your dealer verify converter stall speed and charging pressure before committing to a rebuild.
What chassis wear shows up first and is worth checking regularly?
Like other center-hitch haulers, the articulation and oscillation joints are the first big wear item on this frame. Owners check for play by raising the empty box, backing the truck against a block or curb to flex the hinge, or turning the wheel lock to lock while a second person watches the joint. Pins and bushings wear in gradually; once play reaches metal-to-metal, the truck usually has to be split to rebuild both the articulation and oscillation sides together, since doing only one rarely makes sense once it's apart. Have your dealer verify hitch play both empty and loaded before it progresses further.
What are the known quirks of the 3306 engine in this truck?
The 3306 family behind the D30C is a mechanically governed, largely pre-electronic engine, so its quirks are all mechanical. The gear-driven water pump can fail with little warning and is a common source of coolant loss. The front crankshaft seal is the most frequently reported oil leak. On turbocharged, aftercooled configurations, mineral deposits can plug the aftercooler core over time and reduce charge-air cooling, showing up as excess white smoke or reduced power. The injection pump's internal governor shaft can gum up with age from corrosion or debris, producing hard starting that gets worse hot; some owners find a slight timing adjustment reduces smoke on an otherwise healthy pump. On high-hour used units, a cracked cylinder head from a past overheating event is a common finding. None of this is code-reader diagnostics; it is mechanical fault-finding start to finish.
What electrical issues come up most often on this machine?
Because the D30C predates engine control modules and electronic sensors, what owners call "electrical issues" are almost always basic charging-system items: corroded or loose battery cable terminals, a glazed or slipping alternator belt, or a weak voltage regulator giving a low or erratic charge reading. Slow-crank or no-crank complaints usually trace back to weak or sulfated batteries, a corroded ground strap, or a worn starter solenoid rather than any wiring harness problem. Gauges that read stuck at zero or full, especially coolant temperature and oil pressure, are more often a bad sending unit than a bad gauge. Have your dealer verify charging voltage and ground continuity before replacing an alternator or starter.
What tire and wheel-end wear should an owner expect?
Articulated haulers are hard on tires given the rough, uneven ground they work, so matched tire sets, correct inflation, and regular alignment checks matter more here than on a rigid truck; mixing bias-ply and radial tires on the same axle is a well-known way to accelerate wear. Planetary wheel ends can develop seal leaks and bearing wear as hours accumulate, so a wet or oily wheel hub on inspection is worth tracing back to the seal rather than ignoring. Uneven or feathered tire wear that shows up faster than expected is often a symptom of hitch or oscillation joint play rather than a tire or alignment problem on its own, so check the center joint before condemning a fresh set of tires.
What causes a slow or hesitant dump body raise?
A box that raises slowly or hesitates under load is the most reported hydraulic complaint on haulers of this type, and it's typically low or contaminated hydraulic oil, a clogging suction or return filter, or a hoist pump losing output under load rather than a bad control valve. The D30C's body control is a manually operated lever or pilot circuit, so the solenoid-voltage troubleshooting common on later electronically controlled trucks doesn't apply here; check oil level and condition and the filter first before pulling the pump.
What should I check when looking at a used D30C?
Check articulation and oscillation hitch play empty and loaded first, since that repair is the most expensive if neglected. Look at engine history for evidence of past overheating (head gasket residue, cloudy or oily coolant, aftercooler condition) given the 3306's known heat-related failure points. Inspect hydraulic oil condition and the hoist cylinder rod for pitting or seepage. Confirm tires are a matched set with no unusual wear pattern, and check wheel-end hubs for seal leaks. Run the transmission through the gears once fully warmed up and note any flare, slip, or delayed engagement. Check battery cables, ground straps, and charging output. Given the age of these trucks, ask for maintenance records and weigh visible wear against the hour meter rather than trusting the reading alone; have your dealer verify overall structural and hydraulic condition before you commit to a purchase.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

Need a specific D30C part?

Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.

Search parts in the app