Caterpillartrack-type tractor
Caterpillar D9H
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar D9H is a large conventional track-type tractor built from 1974 into the early 1980s, sitting at the top of Cat's D9 lineage before the platform changed undercarriage designs. It uses the D353 turbocharged diesel inline-six rated at roughly 410 gross hp (306 kW), driving a 3-speed-forward/3-speed-reverse powershift transmission through clutch-and-brake steering. Operating weight varies by configuration and source, ranging from roughly 32.8 tonnes (72,400 lb) for a base tractor to about 42.8 tonnes (94,300 lb) fitted with a ripper. It replaced the D9G (1961-1974) and was itself replaced by the D9L in 1980. Caterpillar also offered dual-tractor and side-by-side push configurations for high-production stripping work alongside the standard single-engine dozer.
Within the D9 lineage, the D9H is the last generation before Caterpillar moved to the elevated-sprocket undercarriage introduced on the D9L, which lifted the final drives clear of ground-level shock loads and became the template for every D9 since. Compared with the D9G it succeeded, the D9H added turbocharging to the same basic engine architecture for a real power jump without a new engine family. In today's used and parts market, the D9H is a legacy machine: most surviving units are in rebuild-and-run mining, quarry, or land-clearing service, where mechanical simplicity and part interchange with D8H/D9G-era components outweigh the lack of modern engine electronics. Buyers evaluate these tractors mainly on undercarriage condition, steering clutch wear, and engine overhaul history rather than remaining book value.
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 D9H specifications
Engine
| Engine model | Cat D353, inline 6-cylinder diesel, turbocharged and aftercooled |
| Gross power | 410 hp (306 kW) at 1800 rpm |
| Displacement | 24.2 L (1,476.8 cu in) |
| Emissions tier | Pre-emissions-regulation era (mid-1970s design); no EPA/Tier certification applies |
| Engine notes | D9H replaced the D9G in production and used this uprated D353 rating as its sole documented engine offering through the model run; no engine change across the D9H run is documented in available spec sheets |
Weights
| Operating weight (standard configuration) | About 42,780 kg (94,300 lb) per most dealer and spec-database listings |
| Weight variance note | Some listings cite a lower figure near 32,840 kg (72,400 lb); this likely reflects a base/shipping weight without ripper and full attachments rather than full operating trim. Treat operating weight as roughly 42.8 t (94,300 lb) fully equipped, and confirm exact trim against the build sheet for a given serial number |
| Configuration offering | Standard (S-blade/dozer) trim is the configuration documented across sources; no LGP variant of the D9H is documented, unlike smaller D-series models of the same era |
Dimensions
| Overall length with blade | 7.24 m (23 ft 9 in) |
| Overall length without blade | 5.61 m (18 ft 5 in) |
| Width over tracks | 3.02-3.05 m (9 ft 11 in - 10 ft 0 in), varies slightly by source |
| Height to top of cab | 3.56 m (11 ft 8 in) |
| Ground clearance | 0.46 m (1 ft 6 in) |
| Track length on ground | 3.35 m (11 ft 0 in) |
| Track gauge | 2.29-2.32 m (7 ft 6 in - 7 ft 7 in) |
| Standard track shoe width | 610 mm (24 in), single-grouser shoe typical for standard trim |
| Ground contact area | Approximately 4.09 m2 (6,336 sq in) per side pair with standard shoes |
| Standard blade width | 4.39-4.42 m (14 ft 5 in - 14 ft 6 in) |
Performance
| Travel speed forward, top gear | 10.8 km/h (6.7-6.8 mph) |
| Travel speed reverse, top gear | 13.2-13.4 km/h (8.2-8.3 mph) |
| Gear count | Powershift transmission, 3 speeds forward and 3 speeds reverse; per-gear intermediate speeds are not published in available spec sheets |
| Ground pressure, standard shoes | 101.4 kPa (14.7 psi) |
| Drawbar pull | Not published for the D9H specifically in available spec sheets; the wider D9-family class (this era) is commonly cited near 161,000 lb peak, but this figure is not confirmed as D9H-specific and should be treated as an approximate class reference only |
| Gradeability | Not documented in available spec sheets for this model; confirm with dealer or OEM technical manual if needed |
Blades
| Standard dozer blade | Straight-type blade, width about 4.4 m (14.5 ft), cutting depth around 560 mm (22 in); blade height not reliably documented across sources |
| Blade capacity, standard blade | About 13.4 m3 (17.5 cu yd) per capacity-rated spec listings tied to this model |
| Other blade options | Universal (U) and semi-universal (SU) blade options were common across the D9 tractor family of this era, but a capacity figure tied specifically and verifiably to the D9H (rather than to other D9-series generations) was not found; only the straight-blade capacity above is confirmed for this model |
| Ripper | Rear-mounted multi-shank ripper was a common factory/dealer-fit attachment for this model, used for ripping rock and hard material ahead of dozing passes |
Service capacities
| Fuel tank | 870 L (229.9 US gal) |
| Cooling system | 104 L (about 27.5 US gal) |
| Engine oil (with filter) | 38 L (about 10 US gal) |
| Power train (transmission/final drive) fluid | 164 L (about 43 US gal) |
| Hydraulic system fluid | 89 L (about 23.5 US gal) |
| Hydraulic system relief pressure | Approximately 38,000 kPa (5,500 psi) per dealer service reference; verify against the machine's own hydraulic schematic before servicing |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
D9H fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with filter) | Approx. 42-43 L (45 US qt / 11.25 US gal) per most refill-capacity tables; an alternate lower figure of about 38 L (40 qt) also circulates - treat as varies by source, confirm against the dipstick range on your unit. | Diesel engine oil meeting Caterpillar's engine oil spec for this era (modern equivalent: Cat DEO). SAE 30 single-grade was the typical era fill for temperate climates; SAE 10W down to about -18°C (0°F); an arctic-grade multigrade below that. Match to the OMM ambient-temperature viscosity chart for your region. |
| Cooling system | Approx. 155 L (41 US gal / 164 qt) in most refill-capacity tables; an alternate figure of about 104 L (27.5 gal) is also cited elsewhere - capacity varies by source and possibly by radiator/fan configuration. | Water plus permanent-type (ethylene glycol) antifreeze/coolant with a Caterpillar corrosion inhibitor (supplemental coolant additive), mixed to the local climate's freeze protection needs. Extended Life Coolant (ELC) is a later Cat product line, not part of this machine's original-issue OMM, but a common modern service refill choice. |
| Fuel tank | 870 L (230 US gal). | No. 2-D diesel fuel; No. 1-D permitted or blended in cold weather to control fuel waxing/gelling. |
| Transmission / power train (torque converter, powershift transmission, bevel gear and steering clutch compartments - shared sump on this generation) | Approx. 129-132 L (34-35 US gal) per most references; a separate combined "power-train" figure of about 164 L (43 gal) is also cited in some spec tables - treat as varies by source/measurement basis, verify against the compartment's own dipstick. | Caterpillar power train/transmission oil to the era's TO-2 type spec (modern equivalent: Cat TDTO / TO-4). SAE 30 single-grade was the typical era fill for temperate climates; a lighter viscosity for cold-climate operation per the OMM chart. |
| Final drives (each side) | Approx. 42-43 L (11.25 US gal) per side per one capacity reference; this exactly matches the engine-oil capacity figure, which suggests a possible transposed value - confirm against the final drive's own fill/level plug before servicing. | Same power-train oil spec used in the transmission/bevel gear compartments for this era (Cat TO-2 type / modern TDTO-TO-4 equivalent); SAE 30 was the typical factory fill for this generation. Do not substitute straight gear oil unless your OMM or dealer confirms it for your serial range. |
| Hydraulic system / tank (pilot-operated implement hydraulic system) | Approx. 89 L (23.5 US gal) per one capacity reference; verify with a dealer or the service manual before relying on this figure. | Caterpillar hydraulic system oil of the era (modern equivalent: Cat HYDO or TDTO), viscosity graded to ambient temperature per the OMM chart. |
| Pivot shaft / equalizer bar | No separate refill/oil capacity documented in available references. The D9H uses a pinned equalizer bar suspension, which is grease-lubricated at the pin/bushing rather than oil-filled. | Multipurpose chassis grease, same as other track and linkage pivot points; grease per the lubrication chart interval, not a bulk fill. |
| Grease (track pins, idlers, rollers, linkage and pivot points) | Applied at grease fittings per the lubrication chart interval; no bulk reservoir quantity applies. | NLGI 2 multipurpose EP chassis grease for normal ambient conditions; NLGI 1 or 0 recommended in sustained sub-freezing/arctic conditions, consistent with Caterpillar's general lubrication guidance for track-type tractors of this era. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar D9H maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 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 D9H beyond the schedule
Predictive Maintenance & Fluid Analysis
On a D353-powered D9H, oil sampling the engine and powershift transmission catches bearing and clutch-pack wear before a slip or knock appears. This tractor still runs the low-drive, non-elevated-sprocket undercarriage, so final drive oil picks up extra dirt and water — sample it on a fixed schedule, not just after a leak shows. Check coolant corrosion-inhibitor level given the D353's cast liners, and log ground pressure and track sag regularly to predict undercarriage replacement before a link or bushing fails mid-push.
Corrective & Common Repairs
D9H corrective work centers on the steering clutch and brake package: a machine pulling to one side usually traces to a worn clutch disc or a dragging, misadjusted brake band, not the D353 engine. Turbocharger shaft play and boost leaks show up as blue smoke and falling power under load. Injection pump and governor drift cause rough idle or sluggish throttle response on this mechanically governed engine. On the undercarriage, watch for turned bushings and stretched chain — the conventional low-drive sprockets wear faster than later elevated-sprocket D9 tractors.
Overhaul & Rebuild Points
Overhaul planning on the D9H starts with the steering clutch and brake package and the final drive gear sets, the main wear items on this clutch-brake-steered, low-drive-sprocket tractor. The powershift transmission and torque converter come next — clutch-pack wear shows up as flare or delayed shifts before a full rebuild is due. The D353 is a heavy, oversquare six built for repeat in-frame overhauls: liners, pistons, and main/rod bearings are the standard kit. Budget undercarriage replacement as a full set; mixing new and worn track components accelerates wear on both.
Seasonal & Environment Servicing
Cold-climate D9H work means checking coolant freeze protection across its large cooling system and confirming the cold-start aid works before the D353's mechanically governed injection has to crank through thick, cold oil. In hot, dusty quarry or mining sites, shorten air cleaner and fuel filter service intervals — this turbocharged engine is more dust-sensitive than the naturally aspirated engine in the D9G. Wet or abrasive ground accelerates steering clutch and track wear, step up undercarriage and final drive oil sampling when the machine works in mud, sand, or standing water.
D9H fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| Coolant Temperature Warning Light | Engine coolant temperature has exceeded the normal operating range. | Low coolant level, plugged radiator core or fins, slipping or failed fan drive, thermostat stuck closed, or sustained heavy load in high ambient heat. | Idle down and stop, let the system cool, then check coolant level and radiator core condition before opening the cap; verify fan and fan drive operation before returning to work. |
| Engine Oil Pressure Warning Light | Engine oil pressure has dropped below the safe minimum for the current speed and temperature. | Low oil level, oil dilution or wrong viscosity, clogged oil pump inlet screen, failing oil pump, or worn main/rod bearings. | Shut the engine down at once, check oil level and condition, and inspect for external leaks before restarting; do not continue running with the light on. |
| Torque Converter Oil Temperature Warning Light / Gauge | Power train (torque converter) oil temperature has reached or exceeded the maximum allowable operating temperature, roughly 130 degC (265 degF). | Low power train oil level, a plugged torque converter oil cooler, sustained stall-speed or high-load work such as pushing in loose material, or worn converter internals reducing charge pressure. | Unload the converter by reducing throttle or shifting to a lower gear, let the machine idle to cool, then check power train oil level and cooler airflow before resuming full load. |
| Charging System (Alternator) Warning Light | The battery is not receiving adequate charge from the charging circuit. | Worn or slipping alternator drive belt, a faulty alternator, or loose and corroded battery or charging circuit connections. | Check belt tension and condition first, then inspect battery terminals and wiring; test alternator output if the light stays on after those checks. |
| Power Train Oil Filter Bypass Indicator | The power train (torque converter/transmission) oil filter is restricted enough that oil is bypassing the element unfiltered. | Filter element loaded with debris or sludge, cold thick oil at startup, or internal transmission wear generating metal fines. | Change the power train oil filter and recheck after a short run; if the indicator trips again quickly, sample the oil for metal contamination. |
| Air Cleaner Service Indicator | Air intake restriction has reached the point where the air filter element needs servicing. | Dust- or debris-loaded primary air filter element, a damaged element, or restricted intake piping. | Service or replace the primary air filter element per the restriction reading, then reset the indicator and confirm it stays clear. |
| Engine Oil Filter Bypass Indicator | The engine oil filter is restricted enough that oil is bypassing the element unfiltered. | Filter element loaded with contaminants, cold thick oil at startup, or an extended service interval. | Change engine oil and filter, then verify the indicator resets and stays clear on the next start. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
D9H attachments & work tools
Blades
D9H blade lineup followed Caterpillar's S/SU/U pattern for this size class: a straight S-type blade for general dozing, a semi-universal (SU) blade with smaller side wings, and a full universal (U) blade with large curved wings for high-volume push work. Standard blade width for the class is about 4.4 m (14.5 ft), cutting depth in the general 500-600 mm (20-24 in) range depending on configuration; a capacity figure specifically tied to the D9H's SU or U blade (rather than to other D9-series generations) is not confirmed, so only the straight-blade capacity of about 13.4 m3 (17.5 cu yd) is documented for this model. This generation added a power-pitch blade feature, letting the operator adjust blade pitch hydraulically from the cab instead of resetting it manually; a powered angle/tilt (PAT/VPAT) blade of the type used on later Cat dozer generations is not documented for the D9H and should not be assumed.
Rippers
Rear ripper attachment was the multi-shank parallelogram type, hydraulically lifted and tilted, with shank sockets so one or more shanks could be run depending on ground hardness. A single-shank heavy-duty ripper was also offered for this class when maximum penetration on hard rock mattered more than swath width, trading shank count for tip force. Fitting a ripper adds on the order of 1.5-2 t (roughly 3,500-4,000 lb) over the bare operating weight of about 42.8 t (94,300 lb).
Winches
By the D9H's 1974 launch, Caterpillar had already wound down its own cable-control-unit (PCU) drum line, so this generation runs pilot-hydraulic implement controls rather than a factory cable/winch takeoff. Winching capability on D9-class dozers of this era came from an aftermarket or dealer-installed logging winch (a PTO- or hydraulically-driven drum) rather than a Caterpillar-badged unit. Exact model/capacity pairings aren't documented specifically for the D9H in factory literature - verify fitment with a dealer or winch manufacturer before assuming compatibility.
Drawbars/counterweights
A rear drawbar/pintle mount was fitted in place of, or alongside, the ripper mount for towing and winching duty on non-ripper configurations. Drawbar-pull figures for the D9 family are usually published as a single class-level number that varies with blade, ripper and undercarriage fitment, so a fixed figure shouldn't be pinned to the D9H specifically without checking the exact configuration. Rear-mounted attachments (ripper or drawbar counterweight) also help balance the machine against the added weight of a full U-blade up front.
Cab/ROPS guarding (forestry/waste)
Standard fitment was an open ROPS/FOPS-type canopy. For forestry and waste-handling duty, machines of this generation could be fitted with heavier screening - grille/radiator guards and canopy-mounted brush and light guards - to protect the cooling package, lighting and glazing from debris and falling material. No factory-cataloged forestry-package spec sheet for the D9H itself was found; guarding of this kind on machines from this era is more often a dealer-fitted or field-fabricated option, so confirm exact fitment before ordering.
Hydraulic arrangement (front/rear tools)
Blade and ripper run on separate hydraulic circuits off the engine-driven pump(s), with pilot-hydraulic (not cable) implement controls standard for this generation. The front circuit handles blade lift/tilt and, on this series, powered blade pitch; the rear circuit handles ripper lift/tilt independently, so both tools can be operated without the operator leaving the seat.
All D9H assemblies by section
Every catalogued assembly group for the Caterpillar D9H. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
D353 Vehicular Engine
6n2093 Water Aftercooler Group
| 6N***93 | Aftercooler Group-Water | 1 |
6n2094 Air Lines Group
| 6N***94 | Air Lines Group | 1 |
2p8673 Alternator Group--24 Volt, 50 Ampere
| 2P***73 | Alternator Group | 1 |
2p1204 Alternator Group--24 Volt, 19 Ampere
| 2P***04 | Alternator Group | 1 |
5s9088 Alternator Assembly--24 Volt, 50 Ampere--Part 2 Of 2
| 5S***88 | Alternator Group-Charging | 1 |
5s9088 Alternator Assembly--24 Volt, 50 Ampere--Part 1 Of 2
| 5S***88 | Alternator Group-Charging | 1 |
2p5113 Alternator Group--24 Volt, 19 Ampere
| 2P***13 | Alternator Group-Charging | 1 |
4h9984 Camshaft Group
| 4H***84 | Camshaft Group; Camshaft Group | 1 |
8n6553 Turbocharger Cartridge Group
| 8N***53 | Cartridge Group-Turbocharger | 1 |
8n9527 Fuel Heater Changeover Group--Field Installation
| 8N***27 | Changeover Group | 1 |
6l4937 Connecting Rod And Piston Group--6 Required
| 6L***37 | Connecting Rod And Piston Group; Connecting Rod & Piston Group | 1 |
2p8708 Fuel Ratio Control Group
| 2P***08 | Control Group-Fuel Ratio; Fuel Ratio Control Group | 1 |
Governor Control (4n7163 N/S)--Part 1 Of 2
| 4N***63 | Control Group-Governor | 1 |
Governor Control (4n7661 N/S)--Part 1 Of 2
| 4N***61 | Control Group-Governor | 1 |
Governor Control (4n7163 N/S)--Part 2 Of 2
| 4N***63 | Control Group-Governor | 1 |
Governor Control (4n7661 N/S)--Part 2 Of 2
| 4N***61 | Control Group-Governor | 1 |
6n1597 Engine Oil Cooler Group
| 6N***97 | Cooler Group-Engine Oil; Engine Oil Cooler Group | 1 |
6n985 Transmission Oil Cooler Group
| 6N***85 | Cooler Group-Transmission Oil | 1 |
6n1577 Cylinder Block Cover Group
| 6N***77 | Cover Group-Cylinder Block | 1 |
6n997 Valve Mechanism Cover Group
| 6N***97 | Cover Group-Valve Mechanism | 1 |
Crankshaft Bearing Replacement Groups
| 7S***04 | Bearing--Front | 1 |
| 7S***05 | Bearing--Intermediate | 4 |
| 7S***06 | Bearing--Center | 1 |
Crankshaft Bearing Replacements
| 6N***47 | Bearing--Center | 1 |
| 6N***48 | Bearing--Center | 1 |
| 6N***49 | Bearing--Intermediate | 4 |
6n2090 Crankshaft Group
| 6N***90 | Crankshaft Group | 1 |
7n6340 Cylinder Head Assembly
| 7N***40 | Cyl Head A | 1 |
7n3630 Cylinder Head Assembly--Field Installation
| 7N***30 | Cyl Head A; Serial No. 47b4208-Up | 1 |
7n1497 Cylinder Block Assembly
| 7N***97 | Cylinder Block As; Cylinder Block Assembly | 1 |
7n2053 Cylinder Block Assembly
| 7N***53 | Cylinder Block Assembly | 1 |
4n5051 Cylinder Block Assembly
| 4N***51 | Cylinder Block Assembly | 1 |
6n2302 Cylinder Block Cover Group
| 6N***02 | Cylinder Block Cover Group | 1 |
4n6627 Cylinder Block Group
| 4N***27 | Cylinder Block Group | 1 |
7n1978 Cylinder Block Group
| 7N***78 | Cylinder Block Group | 1 |
7n3044 Cylinder Block Group
| 7N***44 | Cylinder Block Group | 1 |
7n4013 Cylinder Block Group--Field Installation
| 06***17 | Bolt--19 mm (3/4 Inches) X 273 mm (10.75 Length) | 2 |
| 1D***24 | Bolt--19 mm (3/4 Inches) X 229 mm (9 Inches) | 38 |
| 2A***31 | Bolt 13 mm (1/2 Inches) X 127 mm (6 Inches); Bolt 13 mm (1/2 Inches) X 127 mm (6 Inches) | 10 |
6n996 Cylinder Head Group
| 6N***96 | Cylinder Head Group | 1 |
7n3029 Cylinder Head Group
| 7N***29 | Cylinder Head Group | 1 |
6n2091 Damper Group
| 6N***91 | Damper Group | 1 |
2p5115 Accessory Drive Group
| 2P***15 | Drive Group-Accessory | 1 |
4n6628 Fan Drive Group
| 4N***28 | Drive Group-Fan | 1 |
6n8254 Fan Drive Group
| 6N***54 | Drive Group-Fan | 1 |
4n5095 Fuel Pump And Governor Drive Group
| 4N***95 | Drive Group-Governor & Fuel Pump; Governor & Fuel Injection Pump Drive Gp. | 1 |
4s6625 Power Take-Off Drive Group--Rear
| 4S***25 | Drive Group-Power Take-Off | 1 |
5m6432 Power Take-Off Drive Group--Rear
| 5M***32 | Drive Group-Power Take-Off | 1 |
6n2440 Power Take-Off Drive Group--Rear
| 6N***40 | Drive Group-Power Takeoff | 1 |
5h1429 Oil Pump Drive Group
| 5H***29 | Drive Group-Pump; Oil Pump Drive Group | 1 |
5h1111 Breather And Filler Group
| 5H***11 | Filler & Breather Group; Breather And Filler Group | 1 |
1p9318 Fuel Filter Group
| 1P***18 | Filter Group-Fuel | 1 |
4n5052 Oil Filter Group
| 4N***52 | Filter Group-Oil | 1 |
8h4681 Primary Fuel Filter Group
| 8H***81 | Filter Group-Primary Fuel; Primary Fuel Filter Group | 1 |
8s8061 Primary Fuel Filter And Lines Group
| 8S***61 | Filter Group-Primary Fuel | 1 |
9s2428 Flywheel Group
| 9S***28 | Flywheel Group | 1 |
6n994 Flywheel Housing Group
| 6N***94 | Flywheel Housing Group | 1 |
8s2704 Fuel Transfer Pump (4m9149 N/S)
| 8S***04 | Fuel Transfer Pump | 1 |
Gasket Kits
6n2122 Oil Level Gauge Group
| 6N***22 | Gauge Group-Oil Level (Dipstick) | 1 |
1m6441 Gear Group--Rear
| 1M***41 | Gear Group-Rear | 1 |
3s5160 Glow Plug Group
| 3S***60 | Glow Plug And Wiring Group; Glow Plug Group | 1 |
3s5160 Glow Plug And Wiring Group
| 3S***60 | Glow Plug And Wiring Group; Glow Plug Group | 1 |
4n5136 Governor Group--Part 3 Of 3
| 4N***36 | Governor Group | 1 |
4n5136 Governor Group--Part 1 Of 3
| 4N***36 | Governor Group | 1 |
4n5136 Governor Group--Part 2 Of 3
| 4N***36 | Governor Group | 1 |
8n9771 Fuel Heater Group--Part 2 Of 2
| 8N***71 | Heater Group-Fuel | 1 |
8n9771 Fuel Heater Group--Part 1 Of 2
| 8N***71 | Heater Group-Fuel | 1 |
7n3062 Flywheel Housing Group
| 7N***62 | Housing Group-Flywheel | 1 |
6n993 Front Housing Group
| 6N***93 | Housing Group-Front | 1 |
7n1669 Air Lines Group
| 7N***69 | Lines Group-Air | 1 |
4n6629 Oil Lines Group--Part 2 Of 2
| 4N***29 | Lines Group-Engine Oil | 1 |
4n6629 Oil Lines Group--Part 1 Of 2
| 4N***29 | Lines Group-Engine Oil | 1 |
4n6270 Fuel Injection Valves And Lines Group
| 4N***70 | Lines Group-Fuel Injection | 1 |
7n3641 Turbocharger Oil Lines Group
| 7N***41 | Lines Group-Turbocharger Oil | 1 |
8n8298 Turbocharger Oil Lines Group
| 8N***98 | Lines Group-Turbocharger Oil | 1 |
2p5116 Water Lines Group--Part 1 Of 2
| 2P***16 | Lines Group-Water | 1 |
2p5116 Water Lines Group--Part 2 Of 2
| 2P***16 | Lines Group-Water | 1 |
Water Lines--Aftercooler (6n2092 N/S)
| 6N***92 | Lines Group-Water; Water Lines Group-Aftercooler | 1 |
2p5116 Water Lines Group
| 2P***16 | Lines Group-Water | 1 |
8n7266 Water Lines Group--Turbocharger Housing
| 8N***66 | Lines Group-Water | 1 |
6n1000 Exhaust Manifold Group
| 6N***00 | Manifold Group-Exhaust | 1 |
6n999 Inlet Manifold Group
| 6N***99 | Manifold Group-Inlet | 1 |
9s9350 Service Meter Group
| 9S***50 | Meter Group-Service | 1 |
4n6586 Service Meter Group
| 4N***86 | Meter Group-Service | 1 |
8s3196 Electric Starting Motor Group--24 Volt
| 8S***96 | Motor Group-Electric Starting; Electrical Starting Motor Group | 1 |
Oil Pan (6n995 N/S)
| 6N***95 | Pan Group-Oil | 1 |
6n6641 Connecting Rod & Piston Group--6 Required
| 6N***41 | Piston & Rod Group | 1 |
4s6617 Power Take-Off Group--Part 1 Of 2
| 4S***17 | Power Take-Off Group | 1 |
4s6617 Power Take-Off Group--Part 2 Of 2
| 4S***17 | Power Take-Off Group | 1 |
2s308 Fuel Priming Pump Assembly
| 2S***08 | Pump As-Fuel Priming | 1 |
9m1068 Oil Pimp Group
| 9M***68 | Pump Group-Engine Oil | 1 |
9m1068 Oil Pump (5h1379 N/S)
| 9M***68 | Pump Group-Engine Oil | 1 |
9m1068 Oil Pump Group
| 9M***68 | Pump Group-Engine Oil | 1 |
4n5111 Fuel Pump Housing Group
| 4N***11 | Pump Group-Fuel Injection | 1 |
8s2706 Fuel Priming Pump Group
| 8S***06 | Pump Group-Fuel Priming | 1 |
Fuel Transfer Pump (4m9179 N/S)
| 4M***79 | Pump Group-Fuel Transfer | 1 |
6n1813 Fuel Transfer Pump Group
| 6N***13 | Pump Group-Fuel Transfer | 1 |
6n2450 Oil Pump Group
| 6N***50 | Pump Group-Oil | 1 |
6n6424 Water Pump Group
| 6N***24 | Pump Group-Water | 1 |
7n2669 Turbocharger Shield Group
| 7N***69 | Shield Group-Turbocharger | 1 |
1p9182 Electric Starting Motor Group--24 Volt--Part 2 Of 2
| 1P***82 | Starting Motor Group | 1 |
1p9182 Electric Starting Motor Group--24 Volt--Part 1 Of 2
| 1P***82 | Starting Motor Group | 1 |
5s30 Support Group
| 5S***30 | Support Group-Engine | 1 |
7m6112 Support Group
| 7M***12 | Support Group-Engine | 1 |
6n5123 Solenoid Switch Assembly--24 Volt
| 6N***23 | Switch As-Solenoid | 1 |
6n1575 Belt Tightener Group
| 6N***75 | Tightener Group-Belt | 1 |
Governor Torque Spring (4n4267 N/S)
| 4N***67 | Torque Control Group; Governor Torque Spring Group | 1 |
6n7958 Turbocharger Group
| 6N***58 | Turbocharger Group | 1 |
7n1758 Turbocharger Group
| 7N***58 | Turbocharger Group | 1 |
2p4665 Turbocharger Group
| 2P***65 | Turbocharger Group | 1 |
2p4664 Turbocharger (2p4665 N/S)
| 2P***64 | Turbocharger Group | 1 |
8n8333 Turbocharger Oil Lines Group
| 8N***33 | Turbocharger Group | 1 |
8n6554 Turbocharger Group
| 8N***54 | Turbocharger Group | 1 |
6n2414 Turbocharger Oil Lines Group
| 6N***14 | Turbocharger Oil Lines Group | 1 |
7n1671 Turbocharger Oil Lines Group
| 7N***71 | Turbocharger Oil Lines Group | 1 |
6n998 Valve Mechanism Group
| 6N***98 | Valve-Mechanism Group | 1 |
2p5114 Water Pump Group
| 2P***14 | Water Pump Group | 1 |
Engine Arrangement
7n3240 Basic Engine Arrangement--Part 2 Of 2
| 1P***18 | Filter Group-Fuel | 1 |
| 2P***65 | Turbocharger Group | 1 |
| 2P***16 | Lines Group-Water | 1 |
4n7592 Basic Engine Arrangement--Part 2 Of 2
| 1P***18 | Filter Group-Fuel | 1 |
| 2P***65 | Turbocharger Group | 1 |
| 2P***14 | Water Pump Group | 1 |
4n5998 Basic Engine Arrangement--Part 2 Of 2
| 1P***18 | Filter Group-Fuel | 1 |
| 2P***65 | Turbocharger Group | 1 |
| 2P***13 | Alternator Group-Charging | 1 |
4n7590 Basic Engine Arrangement--Part 1 Of 2
| 1M***41 | Gear Group-Rear | 1 |
| 2P***15 | Drive Group-Accessory | 1 |
| 4H***84 | Camshaft Group; Camshaft Group | 1 |
4n7590 Basic Engine Arrangement--Part 2 Of 2
| 1P***18 | Filter Group-Fuel | 1 |
| 2P***65 | Turbocharger Group | 1 |
| 2P***14 | Water Pump Group | 1 |
7n3241 Basic Engine Arrangement--Part 1 Of 2
| 1M***41 | Gear Group-Rear | 1 |
| 2P***15 | Drive Group-Accessory | 1 |
| 4H***84 | Camshaft Group; Camshaft Group | 1 |
7n3241 Basic Engine Arrangement--Part 2 Of 2
| 1P***18 | Filter Group-Fuel | 1 |
| 2P***65 | Turbocharger Group | 1 |
| 2P***16 | Lines Group-Water | 1 |
7n3240 Basic Engine Arrangement--Part 1 Of 2
| 1M***41 | Gear Group-Rear | 1 |
| 2P***15 | Drive Group-Accessory | 1 |
| 4H***84 | Camshaft Group; Camshaft Group | 1 |
4n7665 Basic Engine Arrangement--Part 2 Of 2
| 1P***18 | Filter Group-Fuel | 1 |
| 2P***65 | Turbocharger Group | 1 |
| 2P***13 | Alternator Group-Charging | 1 |
4n7665 Basic Engine Arrangement--Part 1 Of 2
| 1M***41 | Gear Group-Rear | 1 |
| 2P***15 | Drive Group-Accessory | 1 |
| 4H***84 | Camshaft Group; Camshaft Group | 1 |
4n7592 Basic Engine Arrangement--Part 1 Of 2
| 1M***41 | Gear Group-Rear | 1 |
| 2P***15 | Drive Group-Accessory | 1 |
| 4H***84 | Camshaft Group; Camshaft Group | 1 |
4n5998 Basic Engine Arrangement--Part 1 Of 2
| 1M***41 | Gear Group-Rear | 1 |
| 2P***15 | Drive Group-Accessory | 1 |
| 4H***84 | Camshaft Group; Camshaft Group | 1 |
6n3057 Engine Arrangement--Air Conditioning
| 2P***69 | Compressor Group-Refrigerant; Refrigerant Compressor Group | 1 |
| 4N***98 | Basic Engine Arrangement | 1 |
| 6N***57 | Engine Arrangement | 1 |
D9H serial number reference
The PIN/serial plate on a D9H is mounted at the rear of the machine, high on the left side at the end of the left frame rail; a rear ripper attachment can hide it from view. Like other pre-2001 Caterpillar machines, the D9H serial is 8 characters: a 3-character prefix followed by a sequence number. The prefix identifies the specific build (standard single tractor, dual tandem front/rear, or side-by-side left/right) and the plant/market batch; the digits that follow are just the unit's running number within that build.
| Prefix | Identifies | Notes |
|---|---|---|
| 90V | Standard single-unit D9H track-type tractor, Power Shift | Base D9H configuration and by far the most common prefix for the model. 3-speed Power Shift transmission. Diesel is the Caterpillar D353 turbocharged six-cylinder, roughly 306 kW (410 hp) net flywheel power, 24.1 L displacement. Spans most of the D9H production run, 1974 into the early 1980s, before the line moved to the D9L. Built for the U.S. market. |
| 97V | Dual D9H (DD9H) tandem push-dozer, front tractor unit | Front half of the coupled two-tractor DD9H push-dozer, controlled from a single steering station on the front unit, with the rear tractor's controls linked to follow it. Same Power Shift/D353 driveline as the standard tractor; a mated pair combines to roughly 610 kW (820 hp). Limited-production run, mid-to-late 1970s. Built for the U.S. market. |
| 98V | Dual D9H (DD9H) tandem push-dozer, rear tractor unit | Rear half of the coupled DD9H pair, always numbered alongside a 97V front unit and slaved to its controls. Same driveline and production window as 97V. Built for the U.S. market. |
| 12U | Side-by-side (SxS) D9H, right-hand tractor | One of a mated pair of D9H tractors joined side by side to share one extra-wide dozer blade; the pair combines to roughly 610 kW (820 hp). This is the right-hand tractor of the pair, always paired with a 99V left-hand unit, which carries the operator's controls for both machines. Power Shift, D353 diesel. Very limited production, mid-1970s, discontinued by the late 1970s. Built for the U.S. market. |
| 99V | Side-by-side (SxS) D9H, left-hand tractor | Left-hand counterpart to the 12U right-hand SxS tractor, same pairing, driveline, and production window. Carries the operator's station that controls both machines in the pair. |
Frequently asked questions
What engine does the Caterpillar D9H use?
The D9H uses Caterpillar's D353 diesel inline-six with turbocharging, rated at approximately 410 gross hp (306 kW). This was a turbocharged step up on the same basic engine architecture from the naturally aspirated engine in the preceding D9G.
What is the operating weight of the Caterpillar D9H?
Operating weight varies by configuration and source: roughly 32.8 tonnes (72,400 lb) for a base tractor with a standard blade, up to about 42.8 tonnes (94,300 lb) for a ripper-equipped unit. Confirm the exact figure against the specific machine's configuration and serial number.
What replaced the Caterpillar D9H?
The D9H was replaced by the D9L in 1980, which introduced Caterpillar's elevated-sprocket undercarriage to the D9 line. The D9H itself had replaced the D9G, produced from 1961 to 1974.
What D9H owners discuss
What drivetrain does the D9H use, and what powertrain problems come up most in the field?
The D9H runs a torque-converter-drive powershift transmission, not a direct-drive gearbox, carrying more horsepower than the D9G it replaced on the same basic torque-converter/powershift layout. The most-reported failure path is transmission oil contamination: worn clutch-pack material sheds metal fines that load up the magnetic screen, and once that debris circulates it damages the torque converter and the pressure control valves. Reported symptoms include hesitation shifting forward to reverse, a thump felt in gear or in neutral, and low or zero pressure reading at the speed or direction clutch when checked at the control valve. Field habit: pull and check the magnetic screen on a regular interval, and treat metal on the screen as a reason to sample the transmission oil before putting the machine back to work. A transmission or converter fault that affects clutch engagement is a drivetrain safety item — have a dealer confirm repairs before returning the machine to service.
How does the D9H's undercarriage wear compared to other large Cat dozers, and what do owners watch for?
Owners describe the same wear order seen on other large Cat crawler dozers: bushings and sprockets wear fastest under heavy drawbar or ripping work, with rail, roller, and idler wear following behind. A stretched chain past its adjustment range accelerates sprocket wear because the pitch mismatch re-cuts the sprocket teeth, and a loose, snaking chain marks up roller flanges and track guards as well. Mechanics caution against mixing heavily worn rails or sprockets with new components unless the worn parts are built back up to spec first, since the mismatch just transfers wear onto the new part. Aftermarket track chain gets positive reports from owners, holding up well over extended running hours with only routine adjustment. Wear rate varies a lot by application (ripping and scraper-pull duty is harder on the chain than straight dozing) and by which undercarriage package is fitted, so treat any single wear figure as a guide, not a spec.
What engine does the D9H actually use, and does it have any known quirks?
The D9H is powered by Caterpillar's turbocharged D353, a six-cylinder diesel rated well above the engine used in the D9G it replaced. Do not confuse this with the D342 used in D8-series tractors of the same era — that mix-up shows up often in casual write-ups, and the two engines are not interchangeable. Reported quirks center on the fuel system: operators chasing high exhaust temperature and heavy smoke under load have traced it to a failing injector nozzle spray pattern rather than the turbocharger, since a worn nozzle keeps burning fuel later in the stroke and drives exhaust temperature up even when boost and turbo spin are normal. Because the D353 also saw duty in generator sets and other applications, an engine sourced for a swap needs its flywheel and bolt pattern checked against the dozer application before assuming it's a straight fit.
Are there electrical or sensor issues to watch for on a D9H?
This generation of dozer is almost entirely mechanical and hydraulic in its controls, so there is no sensor network to fail the way later electronically-monitored machines have. The electrical side is essentially the starting and charging circuit. Cold starts often use an ether aid, and operators caution to use it sparingly and only while cranking, since over-applying it on a warm engine risks damage. On the charging side, reported alternator problems are mostly bearing wear from dirt and heat buildup, which eventually keeps the rotor from spinning freely or seizes it outright. A deeply discharged battery can also mimic a failing alternator (high charge current, low system voltage), so battery condition should be ruled out before condemning the alternator.
Are there structural weak points on the D9H frame or final drives?
Owners and mechanics point to the mainframe around the equalizer-bar saddle as a known crack point on this generation of long-nose Cat dozer, a frame layout the D9H shares with the D8H/D9G it followed. The long nose carrying the heavy engine acts as a lever over rough ground, so impacts from rocks or stumps transmit shock straight into the frame near the saddle, and cracks tend to open on either side of it. Final drives on the D9H specifically are also reported to see extra strain, since the model carries more horsepower and often a larger blade than the D9G without a corresponding change in final-drive sizing, so drivetrain wear can run ahead of what a lighter D9G would show under the same hours. Any visible mainframe crack, weld repair, or unusual final-drive heat or noise is a structural and drivetrain safety issue — have a dealer or qualified crawler-tractor shop inspect and confirm before the machine returns to work.
What do owners say about the foot brakes and steering clutches on the D9H?
The D9H uses power brakes: the foot pedal presses a spool valve inside the brake actuator housing that applies oil pressure to the brake band, and the linkage stays directly connected to the band so braking still works with the engine off and no oil pressure. Reported complaints include a pedal that goes dead or loses pressure on one side, and a brake that grabs hard instead of easing on smoothly, both of which owners trace to the actuator or its adjustment rather than the band itself. Mechanics describe a field adjustment at the rear housing covers on each side, seating the internal adjuster and then backing it off evenly, since even a small side-to-side adjustment mismatch leaves one brake noticeably weaker than the other. Because steering clutches and brakes are both steering-and-stopping safety items, a one-sided pull under load or an uneven pedal feel should be checked and adjusted by a dealer before the machine goes back into normal operation.
What should I check before buying a used D9H?
Community advice for this model tracks general used-crawler buying practice, focused on the D9H's known weak points. Pull the transmission magnetic screen, or have the seller pull it, and look for metal, since contaminated transmission oil and a worn clutch pack are the most-reported drivetrain failure on this model. Walk the mainframe around the equalizer-bar saddle for cracks or repair welds, a known stress point on this frame generation. Check final-drive housings for oil weep, unusual heat, or gear noise, since these run under the power upgrade that set the D9H apart from the D9G. Inspect undercarriage wear (bushings and sprockets versus rail and roller wear) against the machine's reported hours, and ask what track chain, factory or aftermarket, is currently fitted. Test both foot brakes and steering clutches under load for even, smooth engagement. Confirm the engine is the correct turbocharged D353 dozer-rated variant, not a generator-set or otherwise mismatched engine, with the right flywheel and bolt pattern for the application. Given the age of these machines, have a dealer or independent crawler-tractor specialist complete a full inspection, including frame and final drives, before committing to a purchase.
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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