Stihl 029/039 Chainsaw Service Manual

This 96-page PDF set covers STIHL 029 and 039 chain saws on the 1127-series platform. It combines the 83-page 1992 service manual with a 13-page illustrated parts list prepared for the US 01/2003 parts CD. STIHL states that the two saws share nearly the same design and that model-specific differences are identified where they matter. Written for STIHL servicing dealers and staff, the material is best suited to trained small-engine technicians and experienced mechanics who already understand two-stroke repair and have the required measuring and service tools.

• Engine repair coverage includes exhaust and spark-arrestor service, pressure and vacuum leak testing, oil-seal replacement, complete engine removal, and work on the cylinder, piston, rings, crankshaft, bearings, and engine pan.
• Clutch and cutting-drive procedures cover the clutch drum, spur and rim sprockets, centrifugal clutch, chain-brake disassembly and assembly, front and side chain tensioners, and bar-mounting studs.
• Ignition, starter, and control work addresses spark fault isolation, ignition-module replacement and air-gap setting, flywheel removal, stop-circuit wiring, starter rope and rewind-spring service, and Master Control repairs.
• Fuel-system diagnosis and repair includes carburetor removal, leak testing, internal service, adjustment, tank ventilation, fuel pickup and hose work, plus automatic-choke valve, bellows, filter, hose, and linkage testing.
• Six system troubleshooting charts cover the engine, ignition, fuel delivery, rewind starter, chain lubrication, and clutch/chain-brake drive. A separate automatic-choke diagnostic flowchart supports fault isolation in that system.
• The illustrated parts list supplies 12 exploded assembly views with reference numbers, quantities, and part numbers for the two cylinder groups, engine housing, oil pump and clutch, chain brake, ignition, starter, handle housing, carburetors, and tools.

Engine and Chassis Detail

The engine chapter explains the saw's nonconventional crankcase arrangement, in which the cylinder, piston, crankshaft, and engine pan form the power unit. It documents cylinder-to-pan sealing, correct crankshaft and piston orientation, ring installation, and replacement of the crankshaft as a complete connecting-rod and needle-bearing assembly. Low-compression machines carrying an “N” suffix require the matching special piston, while replacement cylinders are supplied with their corresponding pistons.

Repair coverage extends beyond the powerhead. Separate chapters deal with the AV buffer system, front and handle housings, throttle interlock, switch shaft, adjustable oil pump, suction hose, pickup body, oil-tank vent, and the one-piece fuel-tank/engine-housing replacement procedure. Component-specific torque tables, leak-test specifications, ignition settings, carburetor data, cutting-attachment specifications, capacities, and approved service aids are included.

Carburetor and Automatic-Choke Coverage

The service manual explains the shared Zama/Walbro diaphragm-carburetor construction and identifies differences where individual parts or assembly details change. The companion parts list distinguishes HD-19B, HD-18B for the US-market 029, HD-21B for the US-market 039, and HD-5 configurations, including fixed-jet and high-altitude parts.

Automatic-choke coverage is unusually deep: operating theory, temperature-dependent action, the control valve, bellows, foam and sintered filters, hose connections, carburetor linkage, leak checks, and removed-component tests are all documented. Named visuals include the Automatic Choke schematic, Ignition System troubleshooting flowchart, engine Pressure Test and Vacuum Test setups, Chain Brake assembly views, and the Oil Pump, Clutch exploded illustration. This is not a full wiring-diagram publication; electrical repair is limited to the breakerless magneto ignition, stop circuit, related wiring, and their diagnostic chart.

Parts Changes, Tools, and Repair Cautions

The parts list flags a 029 cylinder and piston change at machine-number notation X 39 305 257 (46.97), a US muffler change at X 39 304 256, dated component revisions, and Brazil-, USA-, Australia-, and Canada-specific parts. These distinctions help prevent ordering from the wrong exploded view or carburetor group.

The service-tool table gives applications and STIHL part numbers, including carburetor/crankcase tester 1106 850 2905, vacuum pump 0000 850 3500, ignition setting gauge 1127 890 6400, piston-ring clamping strap 1127 893 2600, and clutch-spring assembly hook 5910 890 2800.

Several factory cautions matter during repair. The clutch uses a left-hand thread, and STIHL warns that substituting another piston stop for the specified locking strip can damage the piston. The DG fasteners form permanent threads in polymer and light-alloy parts; starting one on a new path instead of the existing thread can damage the housing. Ignition high voltage, fuel handling, the tensioned chain-brake and rewind springs, and sharp cutting components require normal professional workshop precautions.