Stihl Chainsaw 031AV Parts Manual

The STIHL 031AV is a professional-grade chainsaw featuring an air-cooled, two-stroke engine, anti-vibration system (AV), automatic chain oiler, and manual chain brake. This parts manual provides detailed diagrams, part numbers, and ordering information for all components including engine, fuel system, ignition, clutch, guide bar, chain, and housing. Below are key sections for identification, engine parts, cutting attachments, controls, and maintenance.

1. Identification & Specifications 2. Engine Assembly Parts 3. Fuel & Ignition System Parts 4. Cutting Attachment Parts 5. Clutch & Drive System Parts 6. Housing & Handle Parts 7. Anti-Vibration System Parts 8. Controls & Safety Parts 9. Maintenance & Replacement 10. Parts Ordering Information 11. Troubleshooting Parts Issues

Identification & Specifications

Key identifiers: Model 031AV, Serial Number location on crankcase. Engine: Single cylinder, two-stroke, air-cooled. Displacement: XX cc. Power output: XX kW. Fuel: Gasoline/oil mix (50:1). Guide bar lengths: 16", 18", 20". Chain pitch: 3/8". Weight: XX lbs (without cutting attachment).

Component	Specification
Engine Type	Two-stroke, single cylinder
Displacement	XX cc
Fuel/Oil Ratio	50:1 (STIHL HP Ultra oil)
Ignition System	Electronic (breakerless)
Chain Pitch	3/8"
Guide Bar Mount	STIHL 3005 mount pattern
Oil Pump	Automatic (manual override)
Anti-Vibration	AV system with rubber buffers
Safety Features	Chain brake, hand guards
Serial Number	Located on crankcase

Engine Assembly Parts

Cylinder, piston, crankshaft, connecting rod, bearings, seals, crankcase.

Cylinder Assembly: Includes cylinder, fins, decompression valve port.
Piston Assembly: Piston, rings, wrist pin, circlips.
Crankshaft Assembly: Crankshaft, main bearings, seals.
Crankcase: Two halves, gasket, screws.

WARNING! Engine parts are precision fitted; use proper tools for disassembly. Replace gaskets and seals during reassembly.

Fuel & Ignition System Parts

Fuel tank, carburetor, fuel lines, filter, ignition coil, spark plug, stop switch.

Carburetor: WT-XXX model, includes diaphragm, gaskets, jets, adjustment screws.
Fuel System: Tank, cap, filter, lines, primer bulb (if equipped).
Ignition: Flywheel, coil, spark plug boot, stop switch wire.
Air Filter: Foam element, cover, retaining clips.

CAUTION! Ensure fuel lines are routed correctly to prevent leaks. Use genuine STIHL diaphragms for carburetor.

Cutting Attachment Parts

Guide Bar: STIHL Rollomatic, various lengths, replaceable sprocket nose.
Chain: 3/8" pitch, .050" gauge, round-chisel or semi-chisel.
Sprocket: Rim sprocket or spur sprocket, clutch drum.
Bar Nuts: Shouldered nuts and washers.
Chain Tensioner: Screw, adjuster, pin.
Chain Catcher: Mounted on crankcase.
Oil Pump: Gear pump, drive worm, outlet hose.

Clutch & Drive System Parts

Centrifugal clutch, drum, bearing, drive sprocket, worm gear for oil pump.

Clutch Assembly: Shoes, springs, retaining ring. Clutch Drum: Includes bearing and rim sprocket interface. Oil Pump Drive: Worm gear on crankshaft engages pump gear. Drive Shaft: Connects clutch to chain sprocket.

Note: Clutch springs fatigue over time; replace if shoes do not retract. Inspect drum for grooving.

Housing & Handle Parts

Main housing (crankcase cover), rear handle, front handle, AV mounts, screws.

Turn off saw and remove spark plug before disassembly.
Label screws and parts for correct reassembly.
Inspect housing for cracks, especially around handle mounts.

Tip: Use a magnetic tray to organize screws. Replace cracked housings immediately.

Anti-Vibration System Parts

Rubber buffers, springs, washers, mounting brackets.

Front AV: Rubber mounts between engine and front handle.
Rear AV: Rubber mounts between crankcase and rear handle.
Inspection: Check for hardened or cracked rubber. Replace in sets.
Replacement: Support engine, remove handle screws, replace buffers, reassemble.

WARNING! Worn AV mounts increase vibration and can lead to handle failure. Replace promptly.

Controls & Safety Parts

Throttle trigger, interlock, choke lever, stop switch, chain brake band, hand guard.

Maintenance & Replacement

Regularly replace: Air filter, spark plug, fuel filter, chain, guide bar, sprocket. Lubricate: Clutch bearing, throttle linkage.

CAUTION! Use only STIHL-approved parts. Improper parts can cause unsafe operation and void warranty.

Parts Ordering Information

Always reference the part number from the illustrated parts list. Provide model (031AV) and serial number when ordering. Contact an authorized STIHL dealer or visit www.stihlusa.com for parts diagrams and availability. Warranty may apply to certain components.

Troubleshooting Parts Issues

Symptom	Possible Part Failure	Corrective Action
Loss of power	Piston/cylinder scoring, clogged muffler	Inspect cylinder; replace piston/rings; clean muffler screen.
Hard starting	Fuel lines, carburetor diaphragm, ignition coil	Replace fuel lines and filter; rebuild carburetor; test coil.
Excessive vibration	Worn AV mounts, unbalanced flywheel	Replace all AV buffers; check flywheel for damage.
Chain not oiling	Oil pump, drive worm, clogged bar groove	Replace pump gears; clean oil passages; check bar groove.
Clutch slipping	Worn shoes, weak springs, glazed drum	Replace clutch assembly and drum.

Note: For complex repairs, consult a STIHL-trained technician.

Service: Authorized STIHL dealers; www.stihlusa.com