Caterpillar D9G
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar D9G is a large track-type tractor (crawler dozer) built from 1961 to 1974, sized at the top of Caterpillar's dozer line for that era. Power comes from the Cat D353, a turbocharged and aftercooled inline-six diesel of about 24.1 L (1,470 cu in), rated 385 hp (287 kW) gross at 1330 rpm. It drives through a direct-drive transmission with an integral torque divider, a combined torque converter and mechanical drive path that smooths starts and shifts without the fully hydraulic powershift used on later D9-series tractors. Bare tractor weight runs around 29.2 t (64,400 lb), climbing to roughly 39.6-40.8 t (87,300-90,000 lb) or more in full operating trim with blade, ripper, and fluids, depending on configuration. The D9G replaced the D9E and was itself replaced by the D9H in 1974. Caterpillar offered it with period-correct attachment codes for the dozer blade and ripper, including 9A, 9S, 9U, 9R, and 9C, plus a special tandem DD9G push-pull pairing of two D9G tractors joined by a yoke-and-ball coupling for pushloading large wheel scrapers.
Running changes through the 13-year production span were mostly in the operator station, controls, and starting system rather than the core engine rating. Early D9G units used a gasoline pony motor to crank the D353, and production shifted to 24-volt electric direct starting by around 1970. Blade and ripper linkage saw ongoing detail updates, but the D353 stayed at 385 hp for the model's entire run; Caterpillar saved the added-aftercooling power increase for the D9H that followed. Because the D9H carries the same D353 block, many engine and drivetrain components cross over between the two, which keeps parts supply for the D9G more workable than its age alone would suggest. In the used-equipment and parts market the D9G remains active in logging, land clearing, and heavy earthmoving fleets that value its simple mechanical governance and torque-divider drivetrain over electronically managed successors, and it holds a place as a recognized restoration platform, so engine cores, undercarriage components, and blade attachments still carry real resale 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 D9G specifications
Identification & Production
| Production span | 1961 to 1974, roughly a 13-year run. |
| Lineage | Superseded the D9E; replaced in 1974 by the higher-output D9H (410 hp / 306 kW). Do not blend D9H, D9L, D9N, D9R, or D9T figures into D9G specs — later generations use different engines and chassis. |
| Machine type | Crawler (track-type) tractor / dozer with a turbocharged diesel main engine and a gasoline pony/starting engine. |
| Special variants | DD9G (dual-tractor push unit) and side-by-side SxS D9G configurations were built for specific quarry/mining pushing duty; the specs below cover the standard single-tractor machine. |
Engine
| Engine model | Caterpillar D353, four-stroke-cycle diesel, 6 cylinders, turbocharged with aftercooling. |
| Displacement | 24.1 L (1473 cu in). |
| Bore x stroke | 159 x 203 mm (6.25 x 8.00 in). |
| Flywheel power (gross) | 287 kW (385 hp) at 1330 rpm, maintained up to 3000 m (10,000 ft) altitude. |
| Taxable horsepower | 79.4 hp — an old SAE tax-classification figure, not an output rating. |
| Fuel | No. 2 diesel fuel oil, minimum 35 cetane; higher-grade diesel fuel can be used but is not required. |
| Starting system | Main diesel is bump-started by a small gasoline pony/starting engine. On later production (per early-1970s factory literature) the pony engine is itself 24V electric-start, with a 19-amp base alternator (50- or 75-amp alternator optional). Earliest production years are reported to have used rope/hand-crank pony-engine starting — confirm the starting arrangement against the specific serial number. |
| Emissions | Pre-regulation era machine (built 1961-1974); no EPA/Tier emissions certification applies. |
Weights (by configuration)
| Bare tractor, shipping condition (lubricants, coolant, 10% fuel) | approximately 30,800 kg (68,000 lb); some general references cite a lighter bare figure near 29,200 kg (64,400 lb) — treat bare weight as approximate and configuration-dependent. |
| With 9C Cushion push blade, single-cylinder, incl. hydraulics | 37,000 kg (81,500 lb). |
| With 9C Cushion push blade, dual-cylinder, incl. hydraulics | 37,700 kg (83,200 lb). |
| With 9A Angling blade, incl. hydraulics | 38,500 kg (84,800 lb). |
| With 9S Straight blade, incl. hydraulics | 38,800 kg (85,600 lb). |
| With 9U Universal blade, incl. hydraulics | 39,600 kg (87,400 lb) — matches the operating-weight figure of roughly 87,300 lb commonly cited for this model. |
| With 9R Rip-pattern blade, incl. hydraulics | 40,400 kg (89,000 lb). |
| No. 9D single-shank ripper, installed with hydraulics | 5,200 kg (11,400 lb) standard shank; 5,400 kg (11,900 lb) deep-ripping shank. |
| No. 9D multi-shank ripper, installed with hydraulics | 5,300-6,000 kg (11,600-13,200 lb) across single to triple shank. |
| Cab/canopy options | steel cab 580 kg (1,280 lb); canopy 136 kg (300 lb); ROPS canopy with heavy-duty fenders and seat belt 1,160 kg (2,560 lb). |
Dimensions
| Ground clearance | 600 mm (23.5 in), measured from the bottom face of the shoe. |
| Track gauge (center to center) | 2290 mm (90 in). |
| Bare tractor width | 3100 mm (10 ft). |
| Bare tractor height | approximately 3400 mm (11 ft 2 in) overall; a secondary reference of roughly 2600-2800 mm (8 ft 7 in-9 ft 2 in) applies to the hood/operator-platform line, varying with exhaust stack routing and cab or canopy fitted. |
| Bare tractor length (no blade, ripper-drawbar mount) | 5150 mm (16 ft 11 in). |
| Track length on ground | 3350 mm (133 in). |
| Ground contact area, standard shoes, both tracks | 4.10 sq m (6354 sq in) on 610 mm (24 in) shoes. |
| Track shoe width options | 610 mm (24 in) standard; 610 mm and 690 mm (27 in) extreme-service; 690 mm and 760 mm (30 in) also offered. |
| Grouser height | 87 mm (3-7/16 in), from the ground face of the shoe. |
| Front idler oscillation travel | 540 mm (21-1/4 in). |
| With 9A Angling blade | overall length 6830 mm (22 ft 5 in); width 4850 mm (16 ft) straight, 4300 mm (14 ft 2 in) angled. |
| With 9S Straight blade | overall length 6930 mm (22 ft 9 in); width 4350 mm (14 ft 5 in). |
| With 9U Universal blade | overall length 7290 mm (23 ft 11 in); width 4800 mm (15 ft 9 in). |
| With 9R Rip-pattern blade | overall length 6860 mm (22 ft 6 in); width 4390 mm (14 ft 5 in). |
| With 9C Cushion blade | overall length 6600 mm (21 ft 8 in); width 3050 mm (10 ft 1 in). |
| With No. 9D single-shank ripper | overall length approximately 7.57 m (24 ft 10 in) shank lowered, 7.14 m (23 ft 5 in) shank raised; no width increase over bare tractor. |
| With No. 9D multi-shank ripper | overall length 7210 mm (23 ft 8 in) shank lowered, 6780 mm (22 ft 3 in) shank raised; no width increase. |
| With rear cushion push block | overall length 6100 mm (20 ft). |
Performance
| Transmission | Planetary-type power-shift with a single-stage torque converter and torque-divider, combining converter smoothness with direct-drive economy; 3 speeds forward and reverse. A Direct Drive transmission (oil-clutch forward/reverse, no torque converter) was also factory-offered on some D9G production; confirm transmission type against the specific unit's configuration. |
| Forward speed, 1st | 0-3.9 km/h (0-2.4 mph). |
| Forward speed, 2nd | 0-6.8 km/h (0-4.2 mph). |
| Forward speed, 3rd | 0-10.5 km/h (0-6.5 mph). |
| Reverse speed, 1st | 0-4.8 km/h (0-3.0 mph). |
| Reverse speed, 2nd | 0-8.4 km/h (0-5.2 mph). |
| Reverse speed, 3rd | 0-12.7 km/h (0-7.9 mph). |
| Drawbar pull | Peaks near 63,500 kg (140,000 lb) in 1st gear at stall, per the factory pull-versus-ground-speed curve, tapering off through the speed range and dropping further in 2nd and 3rd gear. Usable pull depends on ground traction and equipped tractor weight, not the peak curve value alone. |
| Ground pressure | Roughly 10.7-14 psi (74-97 kPa) on standard 610 mm (24 in) shoes, varying with bare-tractor versus bladed/rippered configuration weight; wider optional 690/760 mm shoes reduce it further. General references sometimes quote about 14.7 psi (101 kPa) for this weight class — that figure is more commonly tied to the heavier, later D9H and should be treated as approximate for the D9G specifically. |
| Gradeability | Not published as a standalone percentage rating in the factory dimensional spec sheet for this model; grade performance is governed by the drawbar-pull curve and available traction. |
| Steering | Hydraulically actuated multiple-disc oil clutches, no adjustment required, with oil-cooled hydraulically boosted contracting-band brakes; clutch and brake assemblies service as a unit. |
| Final drives | Planetary-type gearing with filtered, full-pressure lubrication and floating-ring seals; steel final-drive housings with field-replaceable sprocket rim segments. |
Blades
| Blade lineup | D9G-era factory blades used model-letter designations rather than the later SAE S/SU/A/VPAT naming: 9A Angling, 9S Straight, 9U Universal, 9R Rip-pattern, and 9C Cushion push blade (single- or dual-cylinder). Don't assume SU/VPAT nomenclature for this generation. |
| 9A Angling blade | straight width 4850 mm (16 ft), angled width 4300 mm (14 ft 2 in); overall machine length 6830 mm (22 ft 5 in). |
| 9S Straight blade | width 4350 mm (14 ft 5 in); overall machine length 6930 mm (22 ft 9 in). |
| 9U Universal blade | width 4800 mm (15 ft 9 in); overall machine length 7290 mm (23 ft 11 in). |
| 9R Rip-pattern blade | width 4390 mm (14 ft 5 in); overall machine length 6860 mm (22 ft 6 in); designed for use with the rear ripper and matching counterweight. |
| 9C Cushion push blade | width 3050 mm (10 ft 1 in); overall machine length 6600 mm (21 ft 8 in); offered in single- or dual-cylinder push configuration for scraper-pushing duty. |
| Push Cup attachment (for 9S/9R blades) | bolt-on pushing plate; not usable together with the moldboard push-plate option. |
| Rated SAE blade capacity | Not listed in the factory dimensional spec sheet for this model; confirm cubic capacity per blade type with a dealer or the blade-specific spec sheet rather than assume a figure. |
Attachments (Ripper)
| No. 9D single-shank adjustable ripper | installed weight with hydraulics 5,200 kg (11,400 lb) standard shank, 5,400 kg (11,900 lb) deep-ripping shank; overall tractor length approximately 7.57 m (24 ft 10 in) shank lowered, 7.14 m (23 ft 5 in) shank raised. |
| No. 9D multi-shank adjustable ripper | installed weight with hydraulics 5,300 kg (11,600 lb) single shank, 5,600 kg (12,400 lb) double shank, 6,000 kg (13,200 lb) triple shank; overall length 7210 mm (23 ft 8 in) lowered, 6780 mm (22 ft 3 in) raised. |
| Rear cushion push block | installed weight 1,300 kg (2,870 lb); overall tractor length 6100 mm (20 ft). |
Service Capacities
| Fuel tank | 760 L (200 US gal). |
| Cooling system | 151 L (40 US gal). |
| Engine (diesel) crankcase | 43 L (11.25 US gal). |
| Starting/pony engine crankcase | 2.8 L (0.75 US gal). |
| Transmission, bevel gear & steering clutch compartment (incl. torque converter) | 117 L (31 US gal). |
| Final drive, per side | 43 L (11.25 US gal). |
| Fluid types | No. 2 diesel fuel oil, minimum 35 cetane. Era-correct Caterpillar engine oil and powertrain/transmission oil; cross to the modern equivalent Cat DEO (engine oil) and Cat TDTO (transmission/drive-train oil) product lines for current servicing. Coolant per standard Cat cooling-system fluid specification. |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
D9G fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with filter) | Approx. 42.6 L (45 US qt / 37.5 imp qt) per structured spec references; one general spec aggregator lists a lower ~38 L figure. Treat as a range and confirm against the dipstick fill mark or OMM for your serial range. | Caterpillar diesel engine oil meeting the Cat DEO-class specification for this era. Viscosity graded by ambient air temperature per the OMM chart: heavier single grade (SAE 30) in warm climates, lighter grade or multigrade (SAE 10W or 10W-30) for cold starts near or below freezing. |
| Cooling system | Approx. 151 L (160 US qt, about 40 US gal) per structured spec references; one general aggregator lists a lower ~104 L figure. Varies by source — confirm against the OMM. | Water mixed with Caterpillar-approved permanent-type (ethylene-glycol) antifreeze/coolant plus corrosion inhibitor, mixed to the ratio specified for expected ambient temperature. Add cooling-system conditioner at the OMM's service interval. |
| Fuel tank | Approx. 757 L (200 US gal) per two independent spec references. One aggregator lists a notably higher ~870 L figure — varies by source/tank configuration; confirm against the tank plate or OMM. | No. 2-D diesel fuel; No. 1-D permitted in cold weather to reduce fuel waxing/gelling. |
| Power train (Direct Drive or Power Shift) and bevel gear/steering clutch compartment | The factory spec sheet lists the transmission, bevel gear, and steering clutch compartment (Power Shift configuration, incl. torque converter) at approximately 117 L (31 US gal). Other references cite a higher combined power-train figure near 164 L (43 US gal) without a per-compartment breakdown. Treat as varying by source/configuration and confirm against your OMM. | Caterpillar drivetrain oil to the original Cat TO-2 specification (typically SAE 30 grade for this era); the modern equivalent is Cat TDTO meeting the Cat TO-4 specification. Note: the D9G was factory-offered with two transmission choices -- a Direct Drive unit with an oil-clutch-actuated forward/reverse lever, and a Power Shift unit built around a torque converter and torque-divider for smoother starts. Both share multiple-disc, power-boosted steering clutches (air-cooled or oil-cooled brakes depending on configuration); confirm which transmission type a given unit carries against its OMM or configuration plate. |
| Final drives (each side) | Not separately published in available sources. Final drives share the same drivetrain oil circuit/specification used for the transmission and bevel gear compartment; confirm individual side fill capacity against your OMM. | Same drivetrain oil specification as the transmission/bevel gear compartment: Cat TO-2 (era) or modern Cat TDTO meeting Cat TO-4, typically SAE 30 grade. |
| Hydraulic system (implement/blade circuit) | Approx. 89 L (about 23.5 US gal) reported for the hydraulic fluid circuit in available references. This is a single-source figure — confirm against your OMM. | Caterpillar drivetrain/hydraulic oil to the Cat TO-2 specification (era) or modern Cat TDTO meeting Cat TO-4, matching the grade used elsewhere in the power train on this machine. |
| Pivot shaft | Not documented with a specific fill quantity in available sources. Serviced by checking oil level at a fill/check plug rather than a widely published bulk-quart specification for this model. | Same drivetrain oil specification as the power train: SAE 30 to the Cat TO-2 era specification, or the modern Cat TDTO/TO-4 equivalent. |
| Grease points (track roller frame, equalizer bar end/pin joint, idler, other chassis fittings) | Serviced on a grease-gun interval, not a bulk fluid capacity. | Caterpillar multipurpose-type chassis grease, NLGI 2, EP-rated. Where the machine is fitted with sealed-and-lubricated (SALT) track chain, the track pin/bushing joints carry their own internal oil reservoir and are not grease-serviceable at the chain itself. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar D9G maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 50 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 4,000 h |
|
| Every 6,000 h |
|
Servicing the D9G beyond the schedule
Predictive Maintenance & Fluid Analysis
Pull D353 oil samples on a set interval and watch trend data for turbocharger bearing wear and coolant intrusion before they show up as smoke or boost loss. Sample the torque divider and final drive oil separately, since metal in one does not mean wear in the other. Coolant condition matters too; the aftercooler side is a common spot for silicate dropout on tractors that sit idle between jobs. On pony-start units, log the pony engine's own fuel and oil checks apart from the main D353.
Corrective & Common Repairs
D9G corrective work centers on the turbocharger, the injection pump and governor linkage, and the steering clutch and brake bands. Turbo bearing play and boost loss are common at this age and usually call for a rebuild rather than adjustment. Injection timing drift shows up as rough starts and uneven power under load. Brake bands need periodic adjustment to hold proper engagement; worn bands are a frequent cause of turning drift on grade. Late electric-start units see starter and alternator faults, while early pony-start units see magneto and points failures.
Overhaul & Rebuild Points
Plan a D353 inframe or top-end overhaul around liner, piston, and injector condition once oil analysis or blow-by trends turn unfavorable. The torque divider clutch packs and converter stator are the next major rebuild point; slippage shows up first as sluggish direct-drive response. Final drives and steering clutches wear together and are usually rebuilt as a pair rather than one side alone. On the undercarriage, plan a full chain, roller, and sprocket turn rather than replacing links piecemeal, and check C-frame and blade trunnion bushings whenever the blade comes off.
Seasonal & Environment Servicing
Cold starts are the D9G's biggest seasonal weak point. Pony-start units need a warmed, freshly charged pony engine and clean fuel to fire; electric-start units need full battery capacity and correct antifreeze concentration to protect the aftercooled D353 from freeze-up. In dusty or logging settings, clean the radiator core and turbo intake screening more often than standard, since packed debris cuts cooling and starves the turbo of air. Loosen track tension for soft ground, tighten it for rock work, and match blade or ripper wear parts to the material pushed.
D9G attachments & work tools
Blades
Factory blade choices were the 9S straight blade, 9U universal blade, 9A angle blade, 9R rip blade (paired with the rear ripper), and 9C push blade offered with either one or two hydraulic cylinders. Straight/SU-style blades run roughly 4.3-4.4 m (14-14.5 ft) wide with capacity in the high-teens cu yd (about 13 m3), while the wider U-blade runs into the low-20s cu yd (around 16 m3) class; some special units were fitted with blades out to about 4.9 m (16 ft). No VPAT (variable pitch/angle/tilt) blade was offered — VPAT is a later Cat dozer feature, not part of the D9G-era lineup.
Rippers
Rear-mounted multi-shank ripper was the common rigging, typically paired with the 9R rip-blade combination for general ripping/scarifying work. A single-shank ripper was also offered for jobs needing maximum penetration in hard rock or deep material, trading production rate for shank strength versus the multi-shank unit. Both mount to the rear frame on a hydraulically actuated linkage typical of large dozers of this era.
Winches
A rear-mounted towing/cable winch is listed among the D9G's factory rear-attachment options alongside the ripper and counterweight, used for cable-control pulling duty, log skidding, and general towing/recovery work. The exact factory winch model/line-pull class for this specific vintage isn't well documented in available literature — verify winch make/model against the specific unit's parts book or dealer records.
Drawbars/counterweights
A rear drawbar/hitch was used to pull cable-controlled pull-type scrapers, a common D9G pairing for volume earthmoving; a weight-transferring hitch was also used in tandem push-pull setups (two D9Gs coupled, marketed as the DD9G). A rear counterweight could be fitted in place of the ripper or winch to balance the tractor when running a heavy front blade or in push-loading service.
Cab/ROPS guarding for forestry/waste configs
Standard D9G production ran an open operator station typical of the era; a rounded ROPS-type canopy became available as rollover protection standards emerged later in the model's production life and shows up on documented units. No factory forestry FOPS package is documented specifically for the D9G in available sources — period logging/waste-site operators typically added screened canopy guarding (mesh sized to reject falling limbs/debris) rather than a catalog forestry kit; confirm exact guarding on a given unit with a dealer or restoration source.
Hydraulic arrangement (front/rear tools)
The D9G shares its gear-type hydraulic implement pump architecture with siblings in the same-era large-dozer line, driving the front blade lift/angle/tilt circuit. Rear tools (ripper, winch) run off the same hydraulic system, routed to the rear of the tractor with controls back at the operator station. Exact valve pressure and pump flow figures vary by source and configuration — treat published psi/gpm numbers for this vintage as approximate and verify against the specific unit's service manual.
All D9G assemblies by section
Every catalogued assembly group for the Caterpillar D9G. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Diesel Engine
Aftercooler (9s2625 N/S)
| 9S***25 | Aftercooler | 1 |
Air Lines (4n7389 N/S)
| 4N***89 | Air Lines | 1 |
2p8673 Alternator Group--24 Volt, 19 Ampere
| 2P***73 | Alternator Group | 1 |
2p1204 Alternator Group--24 Volt, 19 Ampere
| 2P***04 | Alternator Group | 1 |
2p5113 Alternator Group--24 Volt, 19 Ampere
| 2P***13 | Alternator Group-Charging | 1 |
Alternator (2p5113 N/S)--24 Volt, 19 Ampere
| 2P***13 | Alternator Group-Charging | 1 |
5s9088 Alternator Assembly--Part 1 Of 2
| 5S***88 | Alternator Group-Charging | 1 |
5s9088 Alternator Assembly--Part 2 Of 2
| 5S***88 | Alternator Group-Charging | 1 |
4h9984 Camshaft Group
| 4H***84 | Camshaft Group; Camshaft Group | 1 |
Connecting Rod And Piston (6l4937 N/S)--6 Required
| 6L***37 | Connecting Rod And Piston Group; Connecting Rod & Piston Group | 1 |
Fuel Ratio Control (2p8708 N/S)
| 2P***08 | Control Group-Fuel Ratio; Fuel Ratio Control Group | 1 |
2p8708 Fuel Ratio Control Group
| 2P***08 | Control Group-Fuel Ratio; Fuel Ratio Control Group | 1 |
Crankshaft (5s5156 N/S)
| 5S***56 | Crankshaft | 1 |
Crankshaft Bearing Replacement Groups
Crankshaft Bearing Replacements
7n3630 Cylinder Head Assembly--Field Installation
| 7N***30 | Cyl Head A; Serial No. 47b4208-Up | 1 |
7n6340 Cylinder Head Assembly
| 7N***40 | Cyl Head A | 1 |
Cylinder Block And Covers (8s8081 N/S)--End View--Part 2 Of 2
| 8S***81 | Cylinder Block And Covers | 1 |
Cylinder Block And Covers (8s5173 N/S)--Side View--Part 1 Of 2
| 8S***73 | Cylinder Block And Covers | 1 |
Cylinder Block And Covers (8s5173 N/S)--End View--Part 2 Of 2
| 8S***73 | Cylinder Block And Covers | 1 |
Cylinder Block And Covers (8s8081 N/S)--Side View--Part 1 Of 2
| 8S***81 | Cylinder Block And Covers | 1 |
7n1497 Cylinder Block Assembly--Field Installation
| 7N***97 | Cylinder Block As; Cylinder Block Assembly | 1 |
8s8068 Cylinder Block Assembly
| 8S***68 | Cylinder Block Assembly | 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 |
Cylinder Head And Valve Mechanism (9s2605 N/S)--Side View--Part 1 Of 2
| 9S***05 | Cylinder Head And Valve Mechanism | 1 |
Cylinder Head And Valve Mechanism (9s2605 N/S)--End View--Part 2 Of 2
| 9S***05 | Cylinder Head And Valve Mechanism | 1 |
2p5115 Accessory Drive Group
| 2P***15 | Drive Group-Accessory | 1 |
Fuel Pump And Governor Drive (4n5095 N/S)
| 4N***95 | Drive Group-Governor & Fuel Pump; Governor & Fuel Injection Pump Drive Gp. | 1 |
4n5095 Fuel Pump And Governor Drive Group
| 4N***95 | Drive Group-Governor & Fuel Pump; Governor & Fuel Injection Pump Drive Gp. | 1 |
Rear Power Take-Off Drive (5m6432 N/S)
| 5M***32 | Drive Group-Power Take-Off | 1 |
Rear Power Take-Off Drive (4s6625 N/S)
| 4S***25 | Drive Group-Power Take-Off | 1 |
Oil Pump Drive (5h1429 N/S)
| 5H***29 | Drive Group-Pump; Oil Pump Drive Group | 1 |
Exhaust Elbow (6n2693 N/S)
| 6N***93 | Exhaust Elbow | 1 |
2p5112 Fan Drive Group
| 2P***12 | Fan Drive | 1 |
5h1111 Breather And Oil Filter Group
| 5H***11 | Filler & Breather Group; Breather And Filler Group | 1 |
Oil Filter (5h1113 N/S)
| 5H***13 | Filter Group-Engine Oil; Oil Filter Group | 1 |
1p9318 Fuel Filter Group
| 1P***18 | Filter Group-Fuel | 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 |
Fuel Injection Valves And Lines (7s9438 N/S)
| 7S***38 | Fuel Injection Valves And Lines | 1 |
Fuel Injection Valves And Lines (7m7423 N/S)
| 7M***23 | Fuel Injection Valves And Lines | 1 |
Fuel Pump And Governor Drive (2m7900 N/S)
| 2M***00 | Fuel Pump And Governor Drive Group | 1 |
Fuel Pump Housing (3s5456 N/S)
| 3S***56 | Fuel Pump Housing Group | 1 |
8s2704 Fuel Transfer Pump Assembly (4m9179 N/S)
| 8S***04 | Fuel Transfer Pump | 1 |
Gasket Kits
1m6441 Camshaft And Power Take-Off Rear Group
| 1M***41 | Gear Group-Rear | 1 |
3s5160 Glow Plug And Wiring Group
| 3S***60 | Glow Plug And Wiring Group; Glow Plug Group | 1 |
Governor (1p9891 N/S)--Part 1 Of 2
| 1P***91 | Governor | 1 |
Governor (1p9891 N/S)--Part 2 Of 2
| 1P***91 | Governor | 1 |
Governor And Decelerator Control (4n7186 N/S)--Part 1 Of 2
| 4N***86 | Governor And Decelerator Control | 1 |
Governor And Decelerator Control (4n7186 N/S)--Part 2 Of 2
| 4N***86 | Governor And Decelerator Control | 1 |
Governor Control (6n2330 N/S)--Part 1 Of 2
| 6N***30 | Governor Control | 1 |
Governor Control (6n2330 N/S)--Part 2 Of 2
| 6N***30 | Governor Control | 1 |
4n5136 Governor Group--Part 3 Of 3
| 4N***36 | Governor Group | 1 |
4s9281 Governor Group--Part 1 Of 3
| 4S***81 | Governor Group | 1 |
5s7496 Governor Group--Part 3 Of 3
| 5S***96 | Governor Group | 1 |
4s9281 Governor Group--Part 2 Of 3
| 4S***81 | Governor Group | 1 |
5s7496 Governor Group--Part 2 Of 3
| 5S***96 | Governor Group | 1 |
4n5136 Governor Group--Part 2 Of 3
| 4N***36 | Governor Group | 1 |
4n5136 Governor Group--Part 1 Of 3
| 4N***36 | Governor Group | 1 |
5s7496 Governor Group--Part 1 Of 3
| 5S***96 | Governor Group | 1 |
4s9281 Governor Group--Part 3 Of 3
| 4S***81 | Governor Group | 1 |
Governor Torque Spring (9s4641 N/S)
| 9S***41 | Governor Torque Spring | 1 |
4n6270 Fuel Injection Valves And Lines Group
| 4N***70 | Lines Group-Fuel Injection | 1 |
Water Lines (2p5116 N/S)
| 2P***16 | Lines Group-Water | 1 |
2p5116 Water Lines Group
| 2P***16 | Lines Group-Water | 1 |
Manifolds (2p4663 N/S)
| 2P***63 | Manifolds | 1 |
Manifolds (1p7882 N/S)
| 1P***82 | Manifolds | 1 |
Service Meter (9s9350 N/S)
| 9S***50 | Meter Group-Service | 1 |
8s3196 Electric Starter Group--24 Volt
| 8S***96 | Motor Group-Electric Starting; Electrical Starting Motor Group | 1 |
6n9245 Oil Cooler Core Assembly
| 6N***45 | Oil Cooler Core Assembly | 1 |
Oil Lines (6n1745 N/S)
| 6N***45 | Oil Lines | 1 |
Oil Lines (5s5196 N/S)
| 5S***96 | Oil Lines | 1 |
Oil Lines (5s1764 N/S)
| 5S***64 | Oil Lines | 1 |
Oil Lines (2p442 N/S)--Part 1 Of 2
| 2P***42 | Oil Lines | 1 |
Oil Lines (2p442 N/S)--Part 2 Of 2
| 2P***42 | Oil Lines | 1 |
Power Take-Off (4s6617 N/S)--Part 2 Of 2
| 4S***17 | Power Take-Off Group | 1 |
Power Take-Off (4s6617 N/S)--Part 1 Of 2
| 4S***17 | Power Take-Off Group | 1 |
2s308 Fuel Priming Pump Assembly
| 2S***08 | Pump As-Fuel Priming | 1 |
9m1068 Oil Pump Assembly (5h1379 N/S)
| 9M***68 | Pump Group-Engine Oil | 1 |
4n5111 Fuel Pump Housing Group
| 4N***11 | Pump Group-Fuel Injection | 1 |
Fuel Pump Housing (4n5111 N/S)
| 4N***11 | Pump Group-Fuel Injection | 1 |
8s2706 Fuel Priming Pump Group
| 8S***06 | Pump Group-Fuel Priming | 1 |
Rack Stop (9s3312 N/S)
| 9S***12 | Rack Stop Group | 1 |
Rear Power Take-Off And Air Compressor Drive (8s5003 N/S)
| 8S***03 | Rear Power Take-Off And Air Compressor Drive | 1 |
Service Meter (9s8955 N/S)
| 9S***55 | Service Meter | 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 Engine Support Group
| 5S***30 | Support Group-Engine | 1 |
7m6112 Engine Support Group
| 7M***12 | Support Group-Engine | 1 |
6n5123 Solenoid Switch Assembly--24 Volt
| 6N***23 | Switch As-Solenoid | 1 |
Torque Control (6n1636 N/S)
| 6N***36 | Torque Control Group | 1 |
Torque Converter And Engine Oil Cooler (8s3912 N/S)
| 8S***12 | Torque Converter And Engine Oil Cooler | 1 |
8s6471 Turbocharger Assembly (1s1103 N/S)
| 8S***71 | Turbocharger Assembly | 1 |
2p4664 Turbocharger Group (2p4665 N/S)
| 2P***64 | Turbocharger Group | 1 |
Turbocharger Group (4n5643 N/S)--Field Installation
| 4N***43 | Turbocharger Group | 1 |
2p5114 Water Pump Group
| 2P***14 | Water Pump Group | 1 |
Engine Arrangement
Engine Arrangements
4n3288 Engine Procurement Arrangement
| 2P***69 | Compressor Group-Refrigerant; Refrigerant Compressor Group | 1 |
| 4N***88 | Engine Procurement Arrangement | 1 |
| 8S***33 | Engine Arrangement | 1 |
D9G serial number reference
The D9G serial/PIN plate is on the dash panel, lower right side of the operator's compartment; the number is also stamped into the rear frame rail, up and to the left of the drawbar. Read the first three characters (two digits plus a letter, e.g. 66A) as the prefix identifying the production series/configuration, then the digits that follow are the sequential unit number within that series.
| Prefix | Identifies | Notes |
|---|---|---|
| 66A | D9G tractor, standard production (single-unit) | Main production run, 1961 to 1974. Cat D353 turbocharged inline-6 diesel, about 24 L (1,473 cu in), rated 385 hp (287 kW). Covers direct-drive and power-shift transmission tractors alike. On early units up to roughly unit 12015 the engine carries the same serial as the tractor; later units get a separate engine serial, matching a documented parts-manual break at that same unit number. |
| 90J | DD9G (Dual D9G), front tractor | Tandem twin-tractor D9G. Front unit carries the single operator's station and the controls for both tractors. Built 1968 to 1974. The two D353 diesels combine for roughly 770 hp (570 kW). Grew out of an independently developed tandem-dozer concept that Caterpillar bought and put into limited factory production. |
| 91J | DD9G (Dual D9G), rear tractor | Rear, unmanned unit of the DD9G tandem pair, slaved to the front tractor's controls. Same 1968-1974 build window and D353 powertrain as the 90J-prefix front unit. |
| 29N | SxS D9G (side-by-side pair), one of two coupled tractors - confirm with dealer | Side-by-side twin-tractor D9G, introduced 1969. Two tractors joined by ball-and-socket linkages at the rear and at the inner tracks, sharing one wide dozer blade (about 7.3 m / 24 ft) for overburden stripping and mine reclamation work. Limited production run. Which physical side (left or right) carries this prefix is not documented in available references. |
| 30N | SxS D9G (side-by-side pair), one of two coupled tractors - confirm with dealer | Companion prefix to 29N in the same side-by-side D9G pairing, from the 1969 production start. Same shared-blade, twin-D353 configuration. Exact left/right assignment not documented in available references. |
Frequently asked questions
What engine does the Caterpillar D9G use?
The D9G runs the Cat D353, a turbocharged and aftercooled diesel inline-six of about 24.1 L (1,470 cu in), rated 385 hp (287 kW) gross at 1330 rpm. It pairs with a direct-drive transmission built around an integral torque divider, not a full hydraulic powershift.
What is the operating weight of the Caterpillar D9G?
Weight varies by configuration: a bare tractor runs around 29.2 t (64,400 lb), while a blade-equipped machine in full operating trim with ripper and fluids can reach roughly 39.6-40.8 t (87,300-90,000 lb) or more.
What replaced the Caterpillar D9G?
Caterpillar replaced the D9G with the D9H in 1974. The D9H kept the same D353 engine block but added more aftercooling, raising output to roughly 410-420 hp. The D9G itself had replaced the earlier D9E in 1961.
What D9G owners discuss
What engine powers the D9G, and do owners consider it reliable?
Does the D9G's starting system change across the production run?
What's the normal behavior of the powershift transmission, and what does a 'won't move' complaint usually mean?
The blade lifts fine empty but sags or won't hold once it's loaded - what's the usual cause?
What undercarriage and final-drive wear patterns are typical for a D9G?
What electrical or charging-system quirks come up on these older D9Gs?
What should a buyer check before purchasing a used D9G?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
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