Model Spotlight

Case 850B Crawler Dozer: Specs, Parts & Common Issues

Produced 1976 – 1981, the Case 850B is the B-generation mid-large frame Case crawler dozer — Case A336BD inline six-cylinder diesel, power shift transmission, and a refined chassis over the original 850. The 850B brought a five-year production refinement of the 850 platform, with updated controls and accessory packages while retaining the workhorse A336BD engine.

Broken Tractor Editorial Team• Updated May 2026• 10 min read

The Case 850B Crawler Dozer is the B-generation mid-large frame Case crawler dozer, produced from 1976 through 1981. The 850B is the direct successor to the original Case 850 and refines that machine's chassis and controls while retaining the proven Case A336BD inline six-cylinder diesel engine. The B-generation introduced updated operator controls, refined accessory packaging, and small undercarriage improvements over the original 850.

For owners and operators today, the 850B sits in a useful spot: it's a 1970s/early-1980s Case dozer with a proven engine (the A336 6-cyl is well-documented and well-supported), a relatively simple power shift drivetrain, and broad parts availability across the 850 family.

The 850B is one machine in a deep 850 family The 850 model line spans roughly 50 years across many sub-generations: original 850 (mid-1970s), 850B (1976–1981), 850C (1981–1987), 850D (1980–1994), 850E (1987–1990), 850G, 850H (2000–2003), 850K (2004–2009), 850L (2009–2014), and 850M (2014–present). When sourcing parts, confirm which 850 generation you're working on — parts that look interchangeable across the family often are not.

At-a-glance specifications

Case 850B — factory specifications

Production years: 1976 – 1981
Predecessor: Case 850 (original, mid-1970s)
Successor: Case 850C (1981 – 1987)
Engine: Case A336BD inline 6-cylinder diesel
Displacement: 336 cu in (~5.5 L)
Power: ~75 horsepower flywheel
Transmission: Power shift
Hydraulics: Open-center implement circuit
Variants: Standard, LGP (Low Ground Pressure)
Operating weight: ~21,500 – 24,500 lb depending on configuration
Blade: 6-way bulldozer blade — angle and tilt blade options
Serial plate location: Right side of operator's platform / chassis frame

How the 850B differs from the original 850

Refined operator controls — the B-generation cleaned up control layout and ergonomics relative to the original 850.
Updated accessory packaging — alternator, starter, and accessory belt routing updated.
Small undercarriage refinements — improved idler seal designs and updated wear strip dimensions on later 850B production.
Power shift standardized — the 850B standardized on the power shift drivetrain across most production.
Same Case A336BD 6-cyl engine — engine architecture unchanged from the original 850, providing parts continuity.

Case A336BD inline 6-cylinder diesel

The Case A336BD is the workhorse Case six-cylinder diesel of the 1970s and early 1980s — 336 cubic inches of displacement (approximately 5.5 liters), inline naturally aspirated configuration. Used across multiple Case industrial and agricultural applications of the era. Approximately 75 horsepower flywheel in 850B-class trim.

The A336 engine ecosystem is broad — accessory parts (water pump, alternator, starter, oil pump) share with other Case industrial 6-cyl applications of the era. Injection pump and injector service is well-documented. Cylinder kits, bearings, and complete engine overhaul parts are available through both Case dealer and aftermarket diesel-engine specialists. Browse the Case Dozer Parts hub for current 850B engine service kits.

Power shift transmission

The 850B uses a power shift transmission — clutchless gear changes under load, with multiple forward and reverse speeds. Power shift was the standard configuration on 850B production and is the same transmission family used on the 850C and 850D successors. Routine service items include shift solenoids and pressure switches, clutch packs, transmission oil cooler, and the transmission filter.

Undercarriage

The 850B undercarriage shares component heritage with the 750 family below and 1150 family above. Sprocket bolt patterns, idler geometries, and master pin dimensions cross-fit on multiple components — confirm by part number against your serial. Track chain, roller, idler, and sprocket are all routine wear items at production-run age, and most field-service 850Bs have seen at least one full undercarriage rebuild.

Browse the Case Dozer Parts hub for current 850B-era undercarriage availability.

Blade system and hydraulics

The 850B ships with a 6-way bulldozer blade — angle and tilt control hydraulically actuated. Blade cylinders, blade-carrier slider blocks, and cutting edges are routine service items. Cutting edge replacement is generally needed every few hundred to few thousand hours of dozing depending on material and operator habit.

Hydraulic implement-circuit pressure is moderate by modern standards — open-center hydraulic systems were standard in this era. Seal kit availability for the blade cylinders is generally good, with aftermarket kits supporting most 850B-era cylinder dimensions.

Common 850B service items

Engine accessory aging

Water pump, alternator, starter, and injection pump on the A336BD are routinely rebuilt or replaced over the engine's service life. Cooling system service (radiator core flush or replacement, fan belt, hose set) is a routine maintenance milestone on 40-plus-year-old machines.

Power shift transmission service

Shift solenoid failure, clutch pack wear, and transmission oil cooler degradation are routine service items at production-run age. Transmission filter and fluid should be on a scheduled service interval — most experienced operators recommend more frequent change-out than the original service manual called for, particularly on high-hour machines.

Hydraulic seal failure

Blade cylinder seal failures are common at this age. Cylinder rod chrome corrosion and seal weep are typical symptoms. Seal kit rebuilds address most cases; severe rod corrosion requires rod replacement.

Undercarriage replacement cycles

Track chains, rollers, idlers, and sprockets all have measurable wear lives. Modern aftermarket undercarriage is available for the 850B family.

Operator station and ROPS

Cab and canopy hardware, seat cushion replacement, and floorboard wear are typical aging-machine issues. ROPS structural integrity should be verified before resale.

Wiring and electrical

40-plus-year-old wiring harnesses are routinely brittle. Hard starts, intermittent gauges, and dim lights are often traced to harness corrosion or insulation failure rather than the underlying component.

Parts and cross-fit components

Component area	What to look for	Notes
Sprockets & segments	Track sprocket assemblies, bolt-on segments	Some 850B-era sprockets cross-fit the 850 / 850C / 850D family on shared bolt patterns.
Idlers & rollers	Front idler assemblies, top and bottom roller sets	Idler and roller bushings see broad mid-large crawler cross-fit.
Track recoil & adjusters	Recoil spring, adjuster yoke, chrome rod	Confirm by serial — running production changes apply.
Master pins	Track master pin and bushing	Master pins share geometry across the 850 family.
Cutting edges & end bits	Standard and severe-duty cutting edges, end bits	Aftermarket cutting edges widely available.
Blade cylinder seal kits	Angle, tilt, lift cylinder seal kits	Confirm cylinder dimensions before ordering.
Engine accessory parts	Water pump, alternator, starter, fuel injection	Case A336BD accessories share parts with other Case industrial 6-cyl applications.
Radiators & cooling	Radiator cores, fan belts, hose sets	Aftermarket radiator and cooling cross-fit available.
Filter service kits	Engine oil, fuel, air, hydraulic filter sets	Filter kits packaged by application speed routine service.
Power shift transmission parts	Shift solenoids, clutch packs, oil cooler	Transmission service parts cross-fit with the 850C and 850D power shift family.
Operator seat	Universal industrial seat with mount kit	Universal Case industrial seats fit the 850B operator station with standard mount kits.

For 850B-era parts inventory and cross-fit confirmation, browse the Case Dozer Parts hub or contact our parts desk directly.

Working on a Case 850B?

The 850B is a 40-plus-year-old machine with a proven Case A336BD 6-cyl engine and broad parts cross-fit with the 850 / 850C / 850D family. Our specialists can verify fitment by serial and walk you through the 850 family's cross-fit options.

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Why the 850B is still in service

The 850B fills a productive sweet spot for mid-large dozer work — bigger than a 750 for serious pushing power but smaller and easier to transport than a 1150. For commercial dirt work, large agricultural site prep, private road maintenance, and major land-clearing, an 850B in good mechanical condition remains a productive machine. The Case A336 six-cylinder diesel is a known, well-supported engine, and the power shift drivetrain is simpler to troubleshoot in the field than the hydrostatic systems on the later 850H / K / L / M.

Broken Tractor Editorial Team

This spotlight was compiled from factory Case service literature for the 850B production family, CNH parts catalogs, Case A336BD engine documentation, and the verified BigCommerce catalog at brokentractor.com.