STIHL BR 380 Repair Manual

The STIHL BR 380 is a professional-grade backpack blower designed for demanding commercial and residential use. This repair manual provides comprehensive instructions for troubleshooting, maintenance, disassembly, and reassembly of the unit. Key sections cover safety precautions, engine specifications, fuel system, ignition system, air filter, cooling system, starting system, carburetor adjustment, and common fault diagnosis. Always refer to the official STIHL manual for complete specifications and torque values.

Safety Precautions

Before attempting any repair, ensure the blower is turned off, cooled down, and the spark plug boot is disconnected to prevent accidental starting. Work in a well-ventilated area away from ignition sources.

Hazard	Preventive Measure
Fuel Fire/Explosion	Drain fuel tank before service. No smoking.
Hot Surfaces	Allow engine to cool completely before disassembly.
Rotating Impeller	Ensure blower tube is removed and unit is secure.
Sharp Edges	Wear cut-resistant gloves when handling fan housing or crankcase.
Chemical Exposure	Use safety glasses and gloves when handling fuel, oil, or solvents.
Electrical Shock	Disconnect spark plug wire and keep away from plug terminal.

Specifications & Identification

Identify your unit via the serial number plate located on the fan housing or crankcase.

• Engine Model: STIHL 2-Mix engine.
• Displacement: 36.3 cc (approx).
• Power Output: 1.4 kW / 1.9 hp.
• Fuel/Oil Mix: 50:1 (High-quality 2-stroke oil with 89+ octane gasoline).
• Ignition System: Electronic, capacitor discharge.
• Carburetor: Zama C1Q-S series (adjustable H, L, LA screws).
• Air Filtration: Dual-stage foam and felt filter.
• Starting System: Rewind starter with decompression valve.
• Impeller Speed: Approx. 7,500 rpm at max power.
• Weight (dry): 9.5 kg (20.9 lbs).

Tools & Workshop Requirements

Gather the necessary tools before beginning repairs.

1. STIHL special tools: Flywheel puller (1110 890 4500), piston stop tool.
2. Standard tools: Torx screwdrivers (T20, T25, T27), socket set (8mm-13mm), needle-nose pliers, circlip pliers.
3. Measuring tools: Feeler gauge set, spark plug gap tool, compression tester.
4. Cleaning supplies: Carburetor cleaner, compressed air, lint-free cloths.
5. Consumables: STIHL HP Ultra oil, gasket kit, fuel line, impulse line, air filter.

WARNING! Use genuine STIHL parts for critical components like fuel lines and gaskets to ensure proper fit and safety.

Engine Disassembly Sequence

Follow this order to avoid damage. Document or photograph wire and hose routing.

1. Remove blower tube, backpack harness, and fuel tank.
2. Remove fan housing, recoil starter assembly, and air filter cover.
3. Disconnect spark plug wire, throttle linkage, and choke rod from carburetor.
4. Remove carburetor, intake manifold, and cylinder cover.
5. Secure piston at Top Dead Center (TDC) using piston stop tool.
6. Remove flywheel nut and use puller to remove flywheel.
7. Remove ignition module (coil).
8. Remove cylinder bolts and carefully lift off cylinder.
9. Remove piston pin circlips and push out piston pin to separate piston from connecting rod.
10. Remove crankcase screws and separate halves (requires heat and careful prying).

CAUTION! Do not force components. Label all parts and fasteners.

Fuel System Repair

Common issues: hard starting, loss of power, engine stalling. Inspect all lines and the fuel filter.

Component	Inspection & Repair
Fuel Tank & Cap	Check for cracks. Ensure vent in cap is clear.
Fuel Lines	Replace if hardened, cracked, or discolored. Use ethanol-resistant line.
Fuel Filter	Replace annually or if clogged. Ensure it sits at bottom of tank.
Impulse Line	Critical for pump operation. Check for leaks or cracks; replace if faulty.
Carburetor Diaphragms	Inspect for stiffness or holes. Replace carburetor kit if damaged.

Tip: Pressurize the fuel tank slightly (by mouth) to check for fuel line leaks.

Ignition System Service

No-spark condition is a common failure. System includes flywheel magnets, ignition module, spark plug, and stop switch.

1. Test spark plug: Remove, reconnect boot, ground electrode to cylinder, pull starter. Look for strong blue spark.
2. Check spark plug gap: Adjust to 0.5 mm (0.020 in).
3. Test ignition module: Use an ohmmeter to check primary and secondary coil resistance (refer to STIHL specs).
4. Inspect flywheel: Look for damaged magnets or keyway. Ensure it is seated properly on crankshaft taper.
5. Check stop switch wire: Disconnect at module; test for continuity to ground when switch is pressed.

WARNING! Never pull the starter with the spark plug removed and boot disconnected without grounding the electrode, as it can damage the ignition module.

Carburetor Adjustment & Cleaning

Default screw positions (turned gently clockwise until seated, then backed out): L screw ~ 1 turn out, H screw ~ 1 turn out, LA (idle) screw ~ 1 turn out.

1. Initial setting: Set screws to default. Start engine and warm up for 5 minutes.
2. Idle adjustment: Turn LA screw to achieve a steady idle (approx. 2800 rpm). Chain should not turn.
3. Low-speed (L) adjustment: Turn L screw for fastest, smoothest idle, then enrich slightly (1/8 turn counter-clockwise).
4. High-speed (H) adjustment: With throttle fully open, adjust H screw for maximum RPM (do not exceed max RPM spec). Lean slightly (1/8 turn clockwise) from peak.
5. Final idle check: Re-check and adjust LA screw after H/L adjustments. Engine should accelerate smoothly without hesitation.

CAUTION! Do not over-lean the H screw, as it can cause engine seizure. Use a tachometer for accuracy.

Air Filter & Cooling System

Restricted airflow causes overheating and power loss.

• Air Filter Service: Remove foam pre-filter and felt main filter. Wash in warm, soapy water. Rinse and air dry completely. Re-oil foam element with STIHL filter oil (squeeze out excess).
• Cooling Fins: Remove cylinder cover and clean debris from cylinder fins and fan housing passages with a brush and compressed air.
• Fan Impeller: Inspect for cracks or damage. Ensure it is securely fastened to the crankshaft.
• Decompression Valve: Test by pressing; it should spring back. Clean or replace if leaking compression.

Starting System Troubleshooting

Hard starting or starter rope not retracting.

Symptom	Check	Solution
Rope pulls very hard	Compression, piston seizure	Check decomp valve; inspect cylinder/piston.
Rope doesn't retract	Starter spring broken/disengaged	Replace spring or rewind assembly.
Starter engages but engine doesn't turn	Sheared flywheel key	Replace key; check flywheel and crankshaft.
Rope pulls with no resistance	Rope not engaged on pulley	Rewind rope onto starter pulley.

Reassembly & Torque Specifications

Use new gaskets and seals. Apply a thin coat of 2-stroke oil to piston, rings, and cylinder wall.

1. Crankcase: Apply sealant (Loctite 518 or equivalent) to mating surfaces. Torque crankcase screws to 10 Nm (88 in-lb) in a crisscross pattern.
2. Piston & Cylinder: Install piston with arrow facing exhaust port. Torque cylinder nuts to 20 Nm (177 in-lb).
3. Flywheel: Clean crankshaft taper and flywheel bore. Torque flywheel nut to 40 Nm (30 ft-lb).
4. Fan Housing/Impeller: Ensure impeller does not contact housing. Torque impeller nut to 35 Nm (26 ft-lb).
5. General Fasteners: M5 screws: 6-8 Nm (53-71 in-lb). M6 screws: 10-12 Nm (88-106 in-lb).

WARNING! Do not over-torque small screws, especially in magnesium housings.

Common Faults & Diagnostic Flowchart

Use this guide for systematic troubleshooting.

Problem	Possible Cause	Corrective Action
Engine won't start	No spark, no fuel, flooded	Check spark, fuel delivery, dry plug.
Starts then dies	Clogged fuel filter, bad impulse line, dirty carb	Replace filter/lines, clean carb.
Loss of power at high speed	Clogged main jet, air leak, faulty ignition	Clean H circuit, pressure test crankcase.
Excessive vibration	Bent crankshaft, unbalanced impeller, loose mounts	Inspect crankshaft runout; replace impeller; tighten mounts.
Overheating	Clogged cooling fins, lean carb setting, low oil mix	Clean fins, enrich L/H screws, use proper mix.
Smoking excessively	Too much oil in mix, crankcase seal leak	Use correct 50:1 mix; replace seals.

Reset: After major repairs, run engine at varying loads for 10 minutes to break in.

Service: For technical assistance or genuine parts, contact an authorized STIHL servicing dealer.