Caterpillaroff-highway trucktruck
Caterpillar 769
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar 769 is a 35-ton class rigid off-highway haul truck built from 1963 to 1967 — Caterpillar's first purpose-built haul truck and the machine that opened the rock-truck market for the company. It uses the mechanical Cat D343 inline-six diesel, naturally aspirated at around 375 hp on early production, moving to the turbocharged D343T later in the run with output climbing toward 400-415 hp depending on configuration. Operating weight runs from roughly 22.7 tonnes (25 tons) empty to about 51 tonnes (56.2 tons) gross loaded, and varies by body and front-axle brake option. The 769 has no earlier Cat haul truck predecessor, and it rides on a powershift transmission, oil-cooled rear disc brakes (a first for Cat), and independent pneumatic-over-oil suspension struts at all four corners. Cat offered it as a rear-dump only, with a molded fiberglass cab and a choice of air/shoe or oil-cooled disc front brakes depending on terrain and duty cycle.
Caterpillar kept the 769 name in production for over four decades, but each generation is effectively a different truck. The 769B (1967-1978) replaced the crack-prone fiberglass cab with steel, added front disc brakes as standard, and pushed the D343T toward 415 hp. The 769C (1978-1995) was a ground-up redesign around the 3408 V8 diesel and an electronically shifted powershift transmission. The 769D (1995-2007) closed out the line with the 3408E and full electronic engine controls before Caterpillar folded the family into the 770 series. None of those later trucks share the original 769's mechanical D343/D343T engine, fiberglass cab, or drivetrain, and mixing parts across generations is a common buyer mistake. In today's market the original 1963-1967 769 survives mainly in quarries, small mines, and vintage/collector fleets running it well past its original service life; its fully mechanical fuel system and total lack of electronic controls make it attractive to operators who want nothing to fail electronically, but parts sourcing leans on rebuilders and remanufactured stock rather than a live, current Cat parts book.
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 769 specifications
Engine
| Engine model | Cat D343, 6-cylinder diesel. Early production (1963) ran naturally aspirated; later production runs used the turbocharged D343T variant. |
| Gross power | 375 flywheel hp at introduction (1963), stepped up to 400 flywheel hp in later production (from 1964) |
| Displacement | approx. 14.6 L (893 cu in), 6 cylinders inline |
| Cylinders | 6, inline |
| Emissions tier | Not applicable — pre-emissions-regulation era machine |
Weights
| Operating weight (empty) | approx. 22.7-24 t / 50,000-53,000 lb (approx. 25 tons), figures vary slightly by source |
| Gross weight (fully loaded) | approx. 51-55.7 t / 112,400-122,860 lb (approx. 56-61 tons), figures vary by source |
| Rated payload | 35 tons (approx. 31.8 t) |
| Ground pressure | Not published |
Dimensions
| Overall length | 7.62-7.65 m (25 ft - 25 ft 1 in) |
| Overall width | 3.58 m (11 ft 9 in) |
| Overall height | 4.06 m (13 ft 4 in) |
| Loading (dump box) height | 3.07 m (10 ft 1 in) |
| Turning radius | 16.66 m (54 ft 8 in) |
| Tires | 18.00 x 25, 32-ply rock-service tires |
Performance
| Top travel speed | 66-69 km/h (41-43 mph), figures vary by source |
| Transmission | Powershift planetary transmission; later production literature lists a barrel-type unit with 9 forward / 1 reverse speeds |
| Braking | Oil-cooled disc brakes on rear axle; air-actuated shoe brakes offered as a front-axle option |
| Steering | Full hydraulic, dual steering cylinders |
| Gradeability | Not published |
Service capacities (summary)
| Fuel tank | 378 L (100 US gal), per the original factory spec sheet |
| Hydraulic system | Shares a combined transmission/brake/steering/hoist oil circuit rated at 227 L (60 US gal); no standalone hydraulic tank fill is broken out for this generation |
| Engine oil | 35 L (9.25 US gal), crankcase with filter |
| Cooling system | 131 L (34.5 US gal) |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
769 fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Engine crankcase (with filter) | 35 L (9.25 US gal) | Caterpillar heavy-duty diesel engine oil, single-grade selected by season: SAE 30 for moderate ambient range, SAE 40 for sustained hot climates, 10W or 10W-30 for cold starts. Nearest modern cross-reference is Cat DEO-family diesel engine oil. |
| Cooling system | 131 L (34.5 US gal) | Permanent-type ethylene-glycol antifreeze/coolant with Caterpillar-approved corrosion inhibitor. Nearest modern cross-reference is Cat ELC-type coolant. |
| Fuel tank | 378 L (100 US gal) | Economy-grade No. 2 diesel fuel oil (ASTM D396 type), minimum cetane rating 35. Premium-quality diesel fuel is usable but not required. |
| Differential | 61 L (16 US gal) | Caterpillar heavy-duty drivetrain/gear oil, viscosity chosen by ambient temperature. Nearest modern cross-reference is Cat TDTO. |
| Final drive (each side) | 12 L (3.25 US gal) per side | Same heavy-duty drivetrain gear oil as the differential fill, Caterpillar planetary-final-drive grade. Nearest modern cross-reference is Cat TDTO. |
| Transmission, brakes, steering & body hoist (integral refill circuit) | 227 L (60 US gal) | One common Caterpillar system oil supplies the powershift transmission, oil-cooled disc brakes, full-hydraulic steering, and twin body-hoist cylinders on this truck — factory literature does not break out a separate standalone hydraulic tank fill for this model. Nearest modern cross-reference is Cat TDTO-type transmission/hydraulic oil. |
| Grease (chassis lube points) | spec only — no fill volume published | General-purpose Caterpillar chassis grease, NLGI 2, lithium base. Exact branded product for this serial range is not confirmed in available factory literature — verify against the dealer parts book. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar 769 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 8,000 h |
|
Servicing the 769 beyond the schedule
Predictive Maintenance & Fluid Analysis
The 769 has no ECM, so oil sampling is the main early-warning tool. Pull engine oil off the D343/D343T at every 250-hour service and watch for babbit and liner-wear metals; sample powershift transmission and torque converter oil for clutch-pack wear, and differential/final-drive oil on each side for gear pitting. Check the disc brake oil-cooling circuit for contamination, since it shares fluid condition with braking performance. Confirm pneumatic-over-oil strut nitrogen charge with a soap-and-water leak check rather than relying on a gauge readout.
Corrective & Common Repairs
Expect fiberglass cab cracking around mounting points and window frames — a known weak spot Cat didn't fix until the steel-cab 769B. Oil-cooled disc brake packs glaze and lose stopping power if the cooling circuit runs low or contaminated. Turbocharged D343T units leak boost at worn intake couplings, costing power on grade. Pneumatic-over-oil struts sag from slow nitrogen leakdown at the seals, throwing ride height off corner to corner. Powershift clutch packs wear early when operators shift under load instead of easing off the throttle first.
Overhaul & Rebuild Points
Major rebuild points on the 769 center on the driveline and brakes. The powershift transmission and torque converter need clutch-pack and seal overhaul once wear metals climb in oil samples. Disc brake packs require refacing or plate replacement once friction material wears past service limits. The D343/D343T benefits from an inframe overhaul — liners, pistons, rings, and main/rod bearings — once compression or oil consumption drifts out of spec. Suspension struts need a full nitrogen-and-oil recharge with seal replacement on a set schedule, not just after a leak complaint.
Seasonal & Environment Servicing
Cold-climate starts on the mechanical D343/D343T need block heaters and correct-viscosity oil in the crankcase and combined transmission/brake/steering/hoist circuit, since there's no ECM to adjust injection timing for temperature. In hot, dusty pit and quarry work, service the air cleaner more often and watch disc brake cooling oil temperature on long grades — the oil-cooled rear brakes shed heat through flow, not air. Wet-season sites call for closer checks on the fiberglass cab seals and pneumatic-over-oil strut boots to keep moisture out of the system.
769 attachments & work tools
Dump body / payload class
Standard dual-slope body with a 3-section tapered floor, rated around 31.8 tonne (35 ton) payload and roughly 17.8 m3 (23.3 yd3) heaped capacity on the original D343T-powered truck. Body is offered lined or unlined depending on material density and site conditions.
Body liners and wear/impact packages
Impact and wear liner packages, external reinforcement plates and rock-shedder panels are offered to protect the body structure, cut spillage and help hold rated payload in abrasive or high-impact material. Liner thickness is typically zoned, heavier under the load-impact area and lighter toward the sides to manage added weight.
Tail extensions, sideboards and custom body work
Tail extensions, sideboards and custom body modifications are available to recover rated payload when hauling low-density material. These are treated as dealer/factory custom body work rather than a catalog work-tool line.
Body mounting and hoist arrangement
The dump body pivots on hinge pins at the rear of the frame and is raised by hydraulic hoist cylinders; there is no bucket-style quick-coupler interface since this is a rigid haul truck, not a loader or excavator. Hoist function is powered off the truck's own hydraulic system, not an add-on work-tool hydraulic kit.
Tires
The original 1960s 769 (D343T engine) specified 18.00x25, 32-ply, E3 bias tires. Later trucks in the 769 lineup are commonly fitted with larger 18.00-33 bias or 18.00R33 radial tires; exact size varies by series/production year and application, verify against the machine's build sheet.
Braking and retarder
Oil-cooled multiple-disc brakes are standard on the rear axle, with front disc brakes offered as a factory-fit option on the original truck (replacing older air-shoe brake practice). Automatic Retarder Control, which lets the engine retard against compression on descents for low-fuel-burn grade control, is documented as a factory option on later trucks in the 769 lineup (769D) — confirm availability for a given serial range with the dealer.
Traction control
A factory-fit Traction Control System to manage wheel slip in poor underfoot conditions is documented as an available option on later 769-lineup trucks (769D). Not confirmed as available on the original D343T-powered 769; verify by serial range.
ROPS/FOPS structure and guarding
A bolt-on Rollover Protective Structure that attaches to four castings welded into the truck frame is documented for later 769-lineup trucks (769D). Optional canopy/rock-guard rail is referenced in truck spec sheets for operation where falling material is a risk; confirm fitment by series.
Exhaust and muffler configuration
Standard configuration runs the exhaust through the body floor for heating (aids material release in cold/sticky conditions), exiting through a notch at the rear right side. Factory options include a full muffled exhaust system or an exhaust diverter for sites with noise or spark restrictions.
Engine starting option (original 769)
On the original D343T-powered 769, buyers could specify either direct electric starting or a 2-cylinder gasoline pony-motor starting engine. This option is specific to the original series and not documented for later 769-lineup trucks with different engines.
All 769 assemblies by section
Every catalogued assembly group for the Caterpillar 769. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Attachments
Air And Hydraulic Brake Control--Front View--Part 2 Of 2--Type 2
Air And Hydraulic Brake Control--Side View Part 1 Of 2--Type 1
Air And Hydraulic Brake Control--Side View--Part 1 Of 2--Type 2
Air And Hydraulic Brake Control--Front View Part 2 Of 2--Type 1
9m4824 Air Motor Assembly
| 9M***24 | Air Motor Assembly | 1 |
8m6159 Air Starting Arrangement--Factory Installation
| 1S***79 | Air Starting Control Group | 1 |
| 7M***12 | Air Starting Motor Group | 1 |
| 7M***44 | Electrical System Group | 1 |
1s479 Air Starting Control Group--Upper Half- Part 1 Of 2
| 1S***79 | Air Starting Control Group | 1 |
1s479 Air Starting Control Group--Lower Half -Part 2 Of 2
| 1S***79 | Air Starting Control Group | 1 |
7m2212 Air Starting Motor Group
| 7M***12 | Air Starting Motor Group | 1 |
4j1943 Air Valve Assembly
| 4J***43 | Air Valve Assembly | 1 |
7d2621 Alarm Assembly
| 7D***21 | Alarm Assembly | 1 |
1s2585 Alternator Assembly--12 Volt, 55 Ampere--Type 2
| 1S***85 | Alternator Assembly | 1 |
1s2585 Alternator Assembly--12 Volt, 55 Ampere--Type 1
| 1S***85 | Alternator Assembly | 1 |
9m6517 Alternator Group--12 Volt, 55 Ampere
| 9M***17 | Alternator Group | 1 |
8m3864 Back-Up Light Group--24 Volt
| 8M***64 | Back-Up Light Group | 1 |
7m6372 Back-Up Light Group--12 Volt
| 7M***72 | Back-Up Light Group | 1 |
7m6371 Back-Up Warning Group--12 Volt--Type 2
| 7M***71 | Back-Up Warning Group | 1 |
8m3896 Back-Up Warning Group--24 Volt--Type 3
| 8M***96 | Back-Up Warning Group | 1 |
8m3896 Back-Up Warning Group--24 Volt--Type 2
| 8M***96 | Back-Up Warning Group | 1 |
7m6371 Back-Up Warning Group--12 Volt--Type 1
| 7M***71 | Back-Up Warning Group | 1 |
7m6371 Back-Up Warning Group--12 Volt--Type 3
| 7M***71 | Back-Up Warning Group | 1 |
8m3896 Back-Up Warning Group--24 Volt--Type 1
| 8M***96 | Back-Up Warning Group | 1 |
7d9376 Basic Alarm Group--12 Volt--Type 1
| 7D***76 | Basic Alarm Group | 1 |
7d9376 Basic Alarm Group--12 Volt--Type 3
| 7D***76 | Basic Alarm Group | 1 |
7d9376 Basic Alarm Group--12 Volt--Type 2
| 7D***76 | Basic Alarm Group | 1 |
7d9375 Basic Alarm Group--24 Volt--Type 3
| 7D***75 | Basic Alarm Group | 1 |
7d9376 Basic Alarm Group--12 Volt--Type 5
| 7D***76 | Basic Alarm Group | 1 |
7d9375 Basic Alarm Group--24 Volt--Type 1
| 7D***75 | Basic Alarm Group | 1 |
7d9375 Basic Alarm Group--24 Volt--Type 2
| 7D***75 | Basic Alarm Group | 1 |
7d9376 Basic Alarm Group--12 Volt--Type 4
| 7D***76 | Basic Alarm Group | 1 |
7m8274 Brake Master Cylinder Assembly
| 7M***74 | Brake Master Cylinder Assembly | 1 |
9m5516 Brake Oil Cooler Group
| 9M***16 | Brake Oil Cooler Group | 1 |
5d5250 Cab Heater Group--24 Volt
| 5D***50 | Cab Heater Group | 1 |
5d5240 Cab Heater Group--12 Volt
| 5D***40 | Cab Heater Group | 1 |
8m3894 Cab Heater Group--12 Volt
| 8M***94 | Cab Heater Group | 1 |
8m3792 Cab Heater Group--24 Volt
| 8M***92 | Cab Heater Group | 1 |
8d246 Cab Visor Group
| 8D***46 | Cab Visor Group | 1 |
2s3025 Protection Cover Group--Oil Filler Cap
| 2S***25 | Cover Group-Protection; Protection Cover Group | 1 |
5d1910 Protection Cover Group--Hydraulic Tank Cap
| 5D***10 | Cover Group-Protection; Protection Cover Group Hydraulic Tank Cap | 1 |
9s8813 Downshift Blocker Group
| 9S***13 | Downshift Blocker Group | 1 |
1s4860 Drive Assembly
| 1S***60 | Drive Assembly | 1 |
7m5544 Electrical System Group--12 Volt--As Viewed From Side Of Truck--Part 6 Of 7
| 7M***44 | Electrical System Group | 1 |
7m5544 Electrical System Group--12 Volt--Batteries--Part 7 Of 7
| 7M***44 | Electrical System Group | 1 |
5d7030 Electrical System Group--12 Volt--Rear Portion As Viewed From Front Left Hand Side Of Truck--Part 4 Of 7
| 5D***30 | Electrical System Group | 1 |
5d7030 Electrical System Group--12 Volt--Front Portion As Viewed From Front Left Hand Side Of Truck--Part 2 Of 7
| 5D***30 | Electrical System Group | 1 |
5d7030 Electrical System Group--12 Volt--Front Portion As Viewed From Front Left Hand Side Of Truck--Part 3 Of 7
| 5D***30 | Electrical System Group | 1 |
5d7030 Electrical System Group--12 Volt--Batteries--Part 7 Of 7
| 5D***30 | Electrical System Group | 1 |
5d7030 Electrical System Group--12 Volt--Front Portion As Viewed From Left Hand Side Of Truck--Part 1 Of 7
| 5D***30 | Electrical System Group | 1 |
7m5544 Electrical System Group--12 Volt--Front Portion As Viewed From Front Left Hand Side Of Truck--Part 2 Of 7
| 7M***44 | Electrical System Group | 1 |
7m5544 Electrical System Group--12 Volt--As Viewed From Front Of Truck--Part 5 Of 7
| 7M***44 | Electrical System Group | 1 |
5d7030 Electrical System Group--12 Volt--As Viewed From Side Of Truck--Part 6 Of 7
| 5D***30 | Electrical System Group | 1 |
7m5544 Electrical System Group--12 Volt--Front Portion As Viewed From Front Left Hand Side Of Truck--Part 1 Of 7
| 7M***44 | Electrical System Group | 1 |
7m5544 Electrical System Group--12 Volt--Rear Portion As Viewed From Front Left Hand Side Of Truck--Part 4 Of 7
| 7M***44 | Electrical System Group | 1 |
5d7030 Electrical System Group--12 Volt--As Viewed From Front Of Truck--Part 5 Of 7
| 5D***30 | Electrical System Group | 1 |
7m5544 Electrical System Group--12 Volt--Front Portion As Viewed From Front Left Hand Side Of Truck--Part 3 Of 7
| 7M***44 | Electrical System Group | 1 |
Electrical System Wiring Diagram--12 Volt System
2m856 Flood Lamp Assembly--12 Volt
| 2M***56 | Flood Lamp Assembly | 1 |
Front Brake--2 Required
8m6160 Front Brake Arrangement
| 8M***60 | Front Brake Arrangement | 1 |
8m8735 Glow Plug And Wiring Group--12 Volt
| 8M***35 | Glow Plug And Wiring Group | 1 |
8f9866 Grease Gun
| 8F***66 | Grease Gun As | 1 |
8m9858 Tool Group
| 8M***58 | Hand Tool Group | 1 |
Additional Parts Of 8m9531 Harness Referred To On Page 174a
| 8M***31 | Harness | 1 |
2m4166 Head Lamp Assembly--12 Volt
| 2M***66 | Head Lamp Assembly | 1 |
8d3300 High Speed Oil Change Group
| 8D***00 | High Speed Oil Change Group | 1 |
9m4801 Hot Water Heater--12 Volt
| 9M***01 | Hot Water Heater | 1 |
9m4802 Hot Water Heater--24 Volt
| 9M***02 | Hot Water Heater Assembly | 1 |
9m5619 Hydraulic Lines Group
| 9M***19 | Hydraulic Lines Group | 1 |
Instrument Panel--12 Volt
7m7910 Instrument Panel Group--12 Volt
| 7M***10 | Instrument Panel Group | 1 |
8m110 Rear Tail, Stop And Reflex Lamp Assembly--12 Volt
| 8M***10 | Lamp As-Tail | 1 |
Name Plates And Transfers
| 1S***21 | Plate -Lubrication Instructions | 1 |
| 1S***34 | Plate; Shifting On Power Shift Console | 1 |
| 1S***16 | Transfer- Caterpillar | 2 |
Rear View Of 7m7906 Panel Assembly Portion Of This Instrument Panel Shown On Page 174
| 7M***06 | Panel Assembly Portion Of This Instrument | 1 |
Rear View Of 6d496 Panel Portion Of Instrument Panel Shown On Page 174b
| 6D***96 | Panel Portion Of This Instrument | 1 |
7m5383 Passenger Seat Group--R.H.
| 7M***83 | Passenger Seat Group--R.H. | 1 |
5d1920 Protection Cover Group--Fuel Tank Cap
| 5D***20 | Protection Cover Group-Fuel Tank Cap; Protection Cover Group | 1 |
8d200 Rear Vision Mirror Group--R.H.--Fender Mounted
| 8D***00 | Rear View Mirror Group | 1 |
9m3990 Rear Vision Mirror Group--L.H.--Cab Mounted
| 9M***90 | Rear Vision Mirror Group | 1 |
7m6368 Rear Vision Mirror Group--R.H.--Fender Mounted
| 7M***68 | Rear Vision Mirror Group | 1 |
6d1180 Rear Vision Mirror Group--L.H.--Type 1
| 6D***80 | Rear Vision Mirror Group--L.H. | 1 |
6d1180 Rear Vision Mirror Group--L.H.--Type 2
| 6D***80 | Rear Vision Mirror Group--L.H. | 1 |
9m5618 Rear Wheel Brake Cooler Arrangment
| 9M***16 | Brake Oil Cooler Group | 1 |
| 9M***18 | Rear Wheel Brake Cooler Arrangment | 1 |
| 9M***19 | Hydraulic Lines Group | 1 |
9m9324 Recording Tachograph Group--24 Volt--Top View--Type 1
| 9M***24 | Recording Tachograph Group | 1 |
9m9323 Recording Tachograph Group--12 Volt--Top View--Type 1
| 9M***23 | Recording Tachograph Group | 1 |
9m9324 Recording Tachograph Group--24 Volt--Top View--Type 2
| 9M***24 | Recording Tachograph Group | 1 |
9m9323 Recording Tachograph Group--12 Volt--Top View--Type 2
| 9M***23 | Recording Tachograph Group | 1 |
9m4509 Rotochamber
| 9M***09 | Rotochamber | 1 |
8m3898 Sun Visor Group
| 8M***98 | Sun Visor Group | 1 |
6d1930 Tachometer And Tachograph Drive Group
| 6D***30 | Tachometer And Tachograph Drive Group | 1 |
9s7978 Tool Group
| 9S***78 | Tool Group-Hand | 1 |
Tools
4d3278 Control Valve Assembly
| 4D***78 | Valve Group-Air Control; -Parking Brake Switch | 1 |
5d2830 Windshield Washer Group
| 5D***30 | Windshield Washer Group | 1 |
Diesel Engine
Aftercooler (9m4825 N/S)
| 9M***25 | Aftercooler Group; Aftercooler Group | 1 |
Air Cleaner--Right Hand Side View
Air Compressor
2s2765 Air Compressor Assembly
| 2S***65 | Air Compressor Assembly | 1 |
Air Compressor Drive
1s2584 Alternator Assembly--24 Volt, 45 Ampere
| 1S***84 | Alternator Assembly | 1 |
9m4180 Alternator Group--24 Volt, 45 Ampere
| 9M***80 | Alternator Group | 1 |
5d6529 Box Assembly
| 5D***29 | Box Assembly | 1 |
9m8398 Box Assembly
| 9M***98 | Box Assembly | 1 |
Breather
Camshaft
Camshaft Drive
5m8271 Air Compressor Assembly
| 5M***71 | Compressor As | 1 |
Connecting Rod And Piston--6 Required
Crankshaft
Crankshaft Bearing Replacement Groups
Crankshaft Bearing Replacements
Cylinder Block And Covers--End View--Part 2 Of 2
Cylinder Block And Covers--Side View--Part 1 Of 2
2s1803 Cylinder Block Assembly
| 2S***03 | Cylinder Block Assembly | 1 |
Cylinder Head And Valve Mechanism--End View--Part 2 Of 2
Cylinder Head And Valve Mechanism--Side View--Part 1 Of 2
1m5061 Tachometer Drive Group
| 1M***61 | Drive Group-Tachometer | 1 |
Drive Pulley And Damper
Electrical System--24 Volt--As Viewed From Side Of Truck--Part 6 Of 7
Electrical System--24 Volt--Front Portion As Viewed From Front Left Hand Side Of Truck--Part 2 Of 7
Electrical System--24 Volt--As Viewed From Front Of Truck--Part 5 Of 7
Electrical System--24 Volt--Front Portion As Viewed From Front Left Hand Side Of Truck--Part 1 Of 7
Electrical System--24 Volt--Batteries--Part 7 Of 7
Electrical System--24 Volt--Front Portion As Viewed From Front Left Hand Side Of Truck--Part 3 Of 7
Electrical System--24 Volt--Rear Portion As Viewed From Front Left Hand Side Of Truck--Part 4 Of 7
Electrical System Wiring Diagram--24 Volt System
Engine Oil Cooler
Engine Support
Exhaust By-Pass
Fan And Shroud--Part 2 Of 2
Fan And Shroud--Part 1 Of 2
9m3223 Oil Filter Group
| 9M***23 | Filter Group-Engine Oil; Oil Filter Group | 1 |
8h7204 Fuel Filter Group
| 8H***04 | Filter Group-Fuel | 1 |
Flywheel
Fuel Filter
Fuel Injection Pump Drive
Fuel Injection Valves And Lines
Fuel Lines
Fuel Pump Housing
Fuel System--Rear View
5m6488 Fuel Transfer Pump Group
| 5M***88 | Fuel Transfer Pump Group | 1 |
Gasket Kits
| 2R***18 | Water Pump | 0 |
| 2S***52 | Diesel Engine Complete | 0 |
| 2S***53 | Valve Grinding | 0 |
7s4280 Glow Plug And Wiring Group--24 Volt
| 7S***80 | Glow Plug And Wiring Group | 1 |
4m308 Glow Plug And Wiring Group--24 Volt
| 4M***08 | Glow Plug And Wiring Group | 1 |
8m2425 Governor Group--With Rack Limiter--Part 1 Of 2
| 8M***25 | Governor Group | 1 |
8m2425 Governor Group--With Rack Limiter--Part 2 Of 2
| 8M***25 | Governor Group | 1 |
Governor Torque Spring
Additional Parts Of 8m9531 Harness Referred To On Page 71
| 8M***31 | Harness | 1 |
Instrument Panel--24 Volt
Instrument Panel Wiring Diagram
Instrument Panel Wiring Diagram--24 Volt Or 12 Volt Systems
7m7147 Combination Stop And Tail Lamp Assembly--24 Volt
| 7M***47 | Lamp As-Stop & Tail | 1 |
1m1882 Flood Lamp Assembly--24 Volt--Type 1
| 1M***82 | Lamp Group | 1 |
1m3379 Head Lamp Assembly--24 Volt--Type 1
| 1M***79 | Lamp Group | 1 |
1m1882 Flood Lamp Assembly--24 Volt--Type 2
| 1M***82 | Lamp Group | 1 |
1m3379 Head Lamp Assembly--24 Volt--Type 2
| 1M***79 | Lamp Group | 1 |
Manifolds--As Viewed From Rear Of Engine--Part 2 Of 2
Manifolds--As Viewed From Right Hand Side Of Engine--Part 1 Of 2
2m1464 Motor Assembly--24 Volt--Part 1 Of 2
| 2M***64 | Motor Assembly | 1 |
2m1464 Motor Assembly--24 Volt--Part 2 Of 2
| 2M***64 | Motor Assembly | 1 |
9m3202 Oil Filter Base Assembly--Top View
| 9M***02 | Oil Filter Base Assembly | 1 |
Oil Lines
4m8026 Oil Pump Assembly
| 4M***26 | Oil Pump Assembly | 1 |
Rear View Of 7m7906 Panel Assembly Portion Of This Instrument Panel Shown On Page 70
| 7M***06 | Panel Assembly Portion Of This Instrument | 1 |
Rear View Of 6d496 Panel Portion Of This Instrument Panel Shown On Page 70b
| 6D***96 | Panel Portion Of This Instrument | 1 |
3s860 Pressure Ratio Regulator Assembly
| 3S***60 | Pressure Ratio Regulator Assembly | 1 |
1s7388 Pressure Ratio Regulator Assembly
| 1S***88 | Pressure Ratio Regulator Assembly | 1 |
1m7022 Fuel Priming Pump Group
| 1M***22 | Pump Group-Fuel Priming | 1 |
Radiator--Right Hand Side View--Part 2 Of 2
Radiator--As Viewed From The Front Of The Truck--Part 1 Of 2
Radiator--As Viewed From Front Of Truck--Part 1 Of 2
Radiator--As Viewed From Front Of The Truck--Part 1 Of 2
4s9643 Crankshaft Replacement Gear Group
| 4S***43 | Replacement Crankshaft Gear Group | 1 |
3s3584 Service Meter And Tachometer Drive Group
| 3S***84 | Service Meter And Tachometer Drive Group | 1 |
2s9582 Service Meter And Tachometer Drive Group
| 2S***82 | Service Meter And Tachometer Drive Group | 1 |
4m1245 Service Meter And Tachometer Drive Group
| 4M***45 | Service Meter And Tachometer Drive Group | 1 |
Speedometer And Tachometer Drive
1m7039 Electric Starter Group--24 Volt
| 1M***39 | Starter Group-Electric; Electric Starter Group | 1 |
7h7290 Disconnect Switch Assembly
| 7H***90 | Switch As-Disconnect | 1 |
4m1812 Solenoid Switch Assembly
| 4M***12 | Switch As-Solenoid | 1 |
Torque Converter Oil Pump Drive
1s9162 Turbocharger Assembly
| 1S***62 | Turbocharger Assembly | 1 |
3s1414 Turbocharger Assembly
| 3S***14 | Turbocharger Assembly | 1 |
Water Lines
2s7209 Water Pump Assembly
| 2S***09 | Water Pump Assembly | 1 |
1s8755 Water Pump Assembly
| 1S***55 | Water Pump Assembly | 1 |
6d498 Wiring Harness
| 6D***98 | Wiring Harness | 1 |
Transmission And Chassis
7m8392 Accumulator Body Group
| 7M***92 | Accumulator Body Group | 1 |
Air And Brake Control--Rear Half--Side View--Part 6 Of 6
Air And Brake Control--Top View Of Tank--Part 4 Of 6
Air And Brake Control--Rear Half--Top View--Part 5 Of 6
Air And Brake Control--Middle Half--Side View--Part 3 Of 6
Air And Brake Control--Front Half--Side View--Part 2 Of 6
Air And Brake Control--Front Half--Top View--Part 1 Of 6
Body--Part 1 Of 2
Body--Part 2 Of 2
Brake Lines--Rear Half--Top View--Part 2 Of 2
Brake Lines--Front Half--Top View -Part 1 Of 2
Brake Lines--Rear Half--Top View -Part 2 Of 2
5d3640 Brake Valve Assembly
| 5D***40 | Brake Valve Assembly | 1 |
Cab--As Viewed From Left Hand Side Of Truck--Part 1 Of 3
Cab--As Viewed From Right Hand Side Of Truck--Part 2 Of 3
Cab--As Viewed From Right Hand Side Of Truck--Part 3 Of 3
5d8047 Control Valve Assembly
| 5D***47 | Control Valve Assembly | 1 |
1s4298 Control Valve Assembly
| 1S***98 | Control Valve Assembly | 1 |
4j4826 Control Valve Group
| 4J***26 | Control Valve Group | 1 |
6d2503 Cowl Group
| 6D***03 | Cowl Group | 1 |
Cowling--As Viewed From Front Of Truck
4j4627 Cylinder Group--3.50" Bore X 14" Stroke--Type 2--Field Installation
| 4J***27 | Cylinder Group | 1 |
4j4627 Cylinder Group--3.50" Bore X 14" Stroke
| 4J***27 | Cylinder Group | 1 |
Differential And Bevel Gear (9m3946 N/S)--Top View
| 9M***46 | Differential And Bevel Gear | 1 |
Differential And Bevel Gear--Top View
8m3876 Door Group--L.H.
| 8M***76 | Door Group | 1 |
5d7930 Door Group--Right Hand
| 5D***30 | Door Group | 1 |
2d8913 Double Check Valve Assembly
| 2D***13 | Double Check Valve Assembly | 1 |
9m7784 Double Universal Joint Assembly--Type 2
| 9M***84 | Double Universal Joint Assembly | 1 |
9m7784 Double Universal Joint Assembly--Type 1
| 9M***84 | Double Universal Joint Assembly | 1 |
Drive Shaft (9m2193 N/S)
| 9M***93 | Drive Shaft | 1 |
Drive Shaft Guard
Exhaust Deflector
3d7090 Hydraulic Oil Filter Group
| 3D***90 | Filter Group-Oil | 1 |
Frame--As Viewed From Rear Right Hand Side Of Truck--Part 2 Of 2
Frame--Left Front View- Part 1 Of 2
Frame--As Viewed From Front Left Hand Side Of Truck--Part 1 Of 2
Frame--Right Rear View--Part 2 Of 2
Frame--Left Front View--Part 1 Of 2
Front Axle And Wheels--18.00 X 25 Tubeless Tires
4j9030 Front Suspension Group--2 Groups Required
| 4J***30 | Front Suspension Group | 1 |
4j9030 Front Suspension Group--2 Required
| 4J***30 | Front Suspension Group | 1 |
2s500 Governor Group
| 2S***00 | Governor Group | 1 |
1s122 Governor Group
| 1S***22 | Governor Group | 1 |
9m5587 Hoist And Steering Pump Assembly
| 9M***87 | Hoist And Steering Pump Assembly | 1 |
Hoist Control
9m1366 Hoist Cylinder Group--2 Groups Required
| 9M***66 | Hoist Cylinder Group | 1 |
Hoist Lines--As Viewed From Left Hand Side Of Truck
Hood
5d6998 Air Horn Assembly
| 5D***98 | Horn Group-Air | 1 |
4j5850 Hydraulic Oil Filter Group
| 4J***50 | Hydraulic Oil Filter Group | 1 |
5j6488 Hydraulic Oil Filter Group
| 5J***88 | Hydraulic Oil Filter Group | 1 |
9m1361 Hydraulic Pump Group
| 9M***61 | Hydraulic Pump Group | 1 |
7m5810 Lubrication Relief Valve Group
| 7M***10 | Lubrication Relief Valve Group | 1 |
2s1485 Lubrication Relief Valve Group
| 2S***85 | Lubrication Relief Valve Group | 1 |
9m6849 Override Selector Valve Group
| 9M***49 | Override Selector Valve Group | 1 |
3k6559 Parking Brake Assembly
| 3K***59 | Parking Brake Assembly | 1 |
Parking Brake Control
Planetary Final Drive
Planetary Transmission--Part 2 Of 2
Planetary Transmission--Part 1 Of 2
Platform--R.H.--Top View
Platform--L.H.--Top View
9f1996 Pneuphonic Horn
| 9F***96 | Pneuphonic Horn | 1 |
1s3216 Pressure Control Group
| 1S***16 | Pressure Control Group | 1 |
2s3532 Pressure Control Group
| 2S***32 | Pressure Control Group | 1 |
2s4996 Pressure Control Valve Group
| 2S***96 | Pressure Control Valve Group | 1 |
2s1398 Pressure Control Valve Group
| 2S***98 | Pressure Control Valve Group | 1 |
7m5826 Range Transmission Arrangement--Right Hand Side View -Part 1 Of 2
| 7M***26 | Range Transmission Arrangement | 1 |
7m5826 Range Transmission Arrangement--As Viewed From The Rear Of The Truck- Part 2 Of 2
| 7M***26 | Range Transmission Arrangement | 1 |
Rear Axle Housing--As Viewed From Left Hand Side Of Truck
1s2508 Rear Brake Group
| 1S***08 | Rear Brake Group | 1 |
6d501 Rear Brake Group
| 6D***01 | Rear Brake Group | 1 |
Rear Wheels And Brakes--18.00 X 25 Tubeless Tires
3j4887 Relay Valve Assembly
| 3J***87 | Relay Valve Assembly | 1 |
5j1919 Relief And Flow Control Valve Group
| 5J***19 | Relief And Flow Control Valve Group | 1 |
5j674 Relief Valve Group
| 5J***74 | Relief Valve Group | 1 |
8m6334 Safety Reset And Converter Hold Valve Group
| 8M***34 | Safety Reset And Converter Hold Valve Group | 1 |
Seat--L.H.--Front View--Part 2 Of 2
Seat--L.H.--Side View--Part 1 Of 2
1s2332 Seat Assembly
| 1S***32 | Seat Assembly | 1 |
7m8391 Selector Body Group
| 7M***91 | Selector Body Group | 1 |
2s7856 Selector Body Group
| 2S***56 | Selector Body Group | 1 |
2s7855 Selector Valve Group
| 2S***55 | Selector Valve Group | 1 |
5m4599 Selector Valve Group
| 5M***99 | Selector Valve Group | 1 |
9m4351 Selector Valve Group
| 9M***51 | Selector Valve Group | 1 |
Steering Gear And Mounting
9m7592 Steering Gear Assembly
| 9M***92 | Steering Gear Assembly | 1 |
Steering Lines--As Viewed From Left Hand Side Of Truck -Part 1 Of 2
Steering Lines--As Viewed From Left Hand Side Of Truck--Part 1 Of 2
Steering Lines--Top View--Part 2 Of 2
Steering Lines--Top View Part 2 Of 2
Steering Linkage--Part 1 Of 2
Steering Linkage--Part 2 Of 2
4j8770 Rear Suspension Group--2 Required
| 4J***70 | Suspension Group-Rear | 1 |
Tank And Valve--Part 2 Of 2--Type 1
Tank And Valve--Part 1 Of 2--Type 1
Tank And Valve--Part 2 Of 2--Type 2
Tank And Valve--Part 1 Of 2
Tank And Valve--Part 1 Of 2--Type 2
Tank And Valve--Part 2 Of 2
8m1071 Three Speed Planetary Transmission Group
| 8M***71 | Three Speed Planetary Torque Divider | 1 |
Three Speed Torque Divider Hydraulic Control
Throttle Control--As Viewed From Right Hand Side Of Truck--Part 1 Of 2
Throttle Control--As Viewed From Front Of Truck--Part 2 Of 2
3s118 Throttle Pressure And Converter Hold Valve Group
| 3S***18 | Throttle Pressure And Converter Hold Valve Group | 1 |
8m1012 Throttle Pressure Valve Group
| 8M***12 | Throttle Pressure Valve Group | 1 |
1t361 Torque Converter Group
| 1T***61 | Torque Converter Group | 1 |
Torque Converter Oil Cooler
Torque Divider
7m5845 Torque Divider Arrangement
| 7M***45 | Torque Divider Arrangement | 1 |
Transfer Gears
Transmission Control--As Viewed From Rear Of Truck -Part 2 Of 2
Transmission Control--As Viewed From Left Hand Side Of Truck- Part 1 Of 2
Transmission Control Linkage Guard
Transmission Hydraulic Control--End View -Part 2 Of 2
Transmission Hydraulic Control--Top View -Part 1 Of 2
Transmission Hydraulic Control--Top View- Part 1 Of 2
Transmission Lines--As Viewed From Rear Right Hand Side Of Truck--Part 2 Of 4
Transmission Lines--As Viewed From Rear Right Hand Side Of Truck--Part 1 Of 4
Transmission Lines--As Viewed From Rear Right Hand Side Of Truck--Part 3 Of 4
Transmission Lines--As Viewed From Rear Right Hand Side Of Truck--Part 4 Of 4
Transmission Pump And Lines--As Viewed From Rear Right Hand Side Of Truck--Part 4 Of 4
Transmission Pump And Lines--As Viewed From Rear Right Hand Side Of Truck--Part 3 Of 4
Transmission Pump And Lines--As Viewed From Rear Right Hand Side Of Truck--Part 1 Of 4
Transmission Pump And Lines--As Viewed From Rear Right Hand Side Of Truck--Part 2 Of 4
4h8461 Universal Joint Assembly
| 4H***61 | Universal Joint Assembly | 1 |
4d2287 Valve Assembly
| 4D***87 | Valve As; -Parking, Service | 1 |
5d3056 Double Check Valve Assembly
| 5D***56 | Valve As-Double Check; -Brakesaver Air Supply | 1 |
3d9943 Horn Valve
| 3D***43 | Valve As-Horn | 1 |
1s3998 Retarder Valve Assembly
| 1S***98 | Valve As-Retarder; -Operator Control | 1 |
4d1084 Brake Valve Assembly
| 4D***84 | Valve Group | 1 |
5j644 Relief Valve Group
| 5J***44 | Valve Group-Relief | 1 |
Windshield Wiper
769 serial number reference
The PIN/serial plate on a 769-series off-highway truck is mounted on the truck frame, typically on the left front frame rail or inside the cab structure near the operator's seat base; older units may also stamp the number on the frame itself. Read the first three characters as the plant/model prefix and the digits that follow as the sequential unit number within that prefix; a plate reading 99F00123 means prefix 99F, unit 123.
| Prefix | Identifies | Notes |
|---|---|---|
| 99F | 769 (original series) | Covers the original Cat 769 off-highway rear-dump truck, produced roughly 1963 to 1967 (commercial production began January 1963). Fitted with the Cat D343 diesel, turbocharged as D343T on later production. Output rose over the run; sources vary on exact figures, ranging from about 375 hp at introduction up to roughly 400-415 hp on later units. 35-ton nominal payload class, Caterpillar's first purpose-built haul truck. Do not confuse with 769B (same D343T family, output nearer 415 hp, 1967-1978) or 769C/769D, which switch to the 3408/3408E V-8 and use their own prefix ranges. |
Frequently asked questions
What engine does the Caterpillar 769 use?
The original 769 (1963-1967) runs the Cat D343 mechanical inline-six diesel, naturally aspirated at around 375 hp on early production, with the turbocharged D343T version arriving later in the run and pushing output toward 400-415 hp depending on configuration. It predates Cat's electronically controlled engines entirely; later 769C/769D trucks use different engines and are not interchangeable with the original 769's drivetrain.
What is the operating weight of the Caterpillar 769?
Empty weight runs around 22.7 tonnes (25 tons), with a gross loaded weight of roughly 51 tonnes (56.2 tons) carrying its rated 35-ton payload class. Exact figures vary by body configuration and front-axle brake option, so treat this as a range rather than a fixed number.
What replaced the Caterpillar 769?
Caterpillar replaced the original 769 with the 769B in 1967, which kept the model name but switched to a steel cab, standard front disc brakes, and higher horsepower. The 769B was followed by the completely redesigned 769C and then 769D before Caterpillar retired the 769 name in favor of the 770-series haul trucks in the 2000s.
What 769 owners discuss
What engine powers the original 1963-1967 Cat 769, and how much horsepower does it make?
The base 769 runs Cat's D343 overhead-cam diesel, offered naturally aspirated at introduction and turbocharged (D343T) on later production. Flywheel output climbed through the run: roughly 280 kW (375 hp) on early units, up to about 298-309 kW (400-415 hp) on later turbocharged trucks. Figures vary by source and serial range, so match horsepower claims to the data plate rather than the model year alone. The D343 family also went into several Cat scrapers and loaders/compactors of the same era, so some parts crossover exists, but owners consistently describe the OHC D343 as costly to rebuild versus later Cat truck engines.
The old spec sheet mentions two starting options on the 769 - what's that about, and does it cause problems?
Early 769s could be ordered with direct electric start or a small petrol auxiliary (pony) starting engine, the same layout Cat used on its track-type tractors of that era. On surviving machines the pony-motor setup is the one that gives trouble: magneto timing drift, worn breaker-point pivot blocks, and flooding are the classic complaints on this style of starting engine across the whole Cat lineup, not unique to the 769. If a pony motor won't hold a spark or backfires on crank, check magneto point gap and timing before suspecting the main engine.
How well do the 769's oil-cooled disc brakes hold up, and what do they need?
The 769 was one of the first Cat trucks to run oil-cooled disc brakes on the rear axle instead of air shoe brakes, with shoe brakes offered only as a front-axle option. The two-piston design combines service, parking, and retarding functions in one oil circuit, so there's no shoe adjustment to chase, but it lives or dies on that oil being clean, at the right level, and circulating through the cooler. Restricted cooler flow or degraded oil is the usual root cause when these systems run hot. Given brakes, parking, and retarding share this circuit, have your dealer verify oil condition and cooler flow before putting a long-idle 769 back to work.
The 769 doesn't have track undercarriage - what wears out on the frame and suspension instead?
In place of leaf springs, the 769 uses independent pneumatic-over-oil suspension struts at each wheel, which absorb shock and were credited at the time with extending frame life versus rigid-mounted competitors. The wear point on surviving trucks is the strut seals and nitrogen/oil charge: leakage shows up as a sagging corner or a harsher ride well before the frame itself cracks. Frame integrity on the base 769 is generally regarded as sound - it's the cab, not the frame, that period owners flag as the weak point.
I've read the original 769's cab was a problem - what happened there?
Cat built the first 769's cab from fiberglass to cut resonance and make crash damage easy to patch. In service the material didn't hold up: period accounts describe the fiberglass cab as prone to cracking under vibration and thermal cycling, enough that it's called out as one of the truck's defining flaws. Cat dropped the approach on the 769B, switching to a steel cab and revised entry layout. On a surviving original 769, expect prior cab repairs or reinforcement, and inspect mounting points for stress cracks before relying on the structure.
Does the original 769 have a reputation for being unreliable?
Mixed. The D343 engine itself carries a solid reputation among owners of the wider D343 family. The truck as a package is a different story: period accounts describe entire fleets of early 769s at one mid-1960s power-plant site sidelined by recurring problems and eventually parked for good rather than repaired, well before the trucks were worn out. Treat the base 769 as a first-generation design - sound powertrain, but expect the truck-specific systems (cab, suspension struts, brake circuit) to need more attention than the engine itself.
What should I check before buying a used original Cat 769?
Confirm generation first: the base 769 (1963-1967) is mechanically distinct from the 769B/C/D that followed it, so match the serial/data plate to the model year, not just the badge. Then walk the truck in this order - cab for cracking or repairs at mounting points; suspension struts at each wheel for leakage or sag; disc-brake oil condition and cooler flow; D343/D343T engine for oil condition, compression, and, if turbocharged, shaft play and boost leaks; and the pony-motor magneto/starting system if fitted. Parts for a machine this old are scarce and often sourced through owner and collector networks rather than a dealer counter, so confirm completeness before assuming anything missing can be easily replaced. Because the disc brakes also carry the parking and retarding function, have your dealer or a qualified tech verify fluid condition and system pressures before putting a used 769 to work.
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Serial-range & configuration variants
This page covers the Caterpillar 769. Related factory variants of the same model family:
769
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