STIHL 038 Service Manual

The STIHL 038 is a professional-grade chainsaw known for its durability and power. This service manual provides comprehensive information for maintenance, troubleshooting, and repair of the STIHL 038 chainsaw. It covers engine specifications, fuel system, ignition system, chain and bar maintenance, safety procedures, and step-by-step repair instructions. Below are key sections for safety, specifications, maintenance procedures, troubleshooting, and parts information.

Safety Information

Always prioritize safety when servicing the STIHL 038 chainsaw. Wear appropriate personal protective equipment (PPE) including safety glasses, gloves, and hearing protection.

Safety Rule	Description
Work Area	Ensure a clean, well-ventilated, and well-lit workspace free of flammable materials.
Chain Brake	Always engage the chain brake before starting any maintenance work.
Fuel Safety	Drain fuel tank before servicing. Use only STIHL-approved fuel mixtures.
Spark Plug	Disconnect spark plug wire to prevent accidental starting.
Sharp Chain	A sharp chain reduces kickback risk. Inspect and sharpen regularly.
Proper Tools	Use only STIHL-approved tools and replacement parts.

Specifications

• Engine Type: Two-stroke, single-cylinder, air-cooled.
• Displacement: 61.5 cc (3.75 cu. in.).
• Power Output: 3.6 kW (4.8 hp).
• Fuel Capacity: 0.55 L (18.6 fl. oz.).
• Oil Capacity: 0.26 L (8.8 fl. oz.).
• Ignition System: Electronic, breakerless.
• Spark Plug: Bosch WSR6F or equivalent.
• Idle Speed: 2,800 rpm.
• Maximum Power Speed: 9,500 rpm.
• Guide Bar Lengths: 40 cm (16") to 50 cm (20") recommended.
• Chain Pitch: 3/8" or .325".

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

1. Daily: Clean air filter, check chain tension and sharpness, inspect for loose fasteners.
2. Weekly: Clean cooling fins, check spark plug condition, clean spark arrestor screen.
3. Monthly: Clean fuel filter, check fuel lines for cracks, inspect anti-vibration elements.
4. Every 3 Months: Clean carburetor, check clutch and sprocket wear, replace spark plug.
5. Annually: Check piston and cylinder for scoring, replace fuel filter, inspect ignition module.

WARNING! Never operate a chainsaw with a loose, damaged, or dull chain.

Engine System

The engine is the heart of the chainsaw. Key components include cylinder, piston, crankshaft, and connecting rod.

1. Cylinder & Piston Inspection: Remove muffler to inspect for scoring or carbon buildup.
2. Compression Test: Should read at least 120 psi. Low compression indicates worn rings or cylinder.
3. Crankcase Seals: Check for leaks which can cause air/fuel mixture issues.
4. Muffler: Clean regularly to prevent power loss and overheating.

CAUTION! Engine components are precision parts. Handle with care and use proper torque specifications.

Fuel System

Includes fuel tank, filter, lines, and carburetor. Always use fresh fuel mix (50:1 gasoline to STIHL HP Ultra oil).

1. Fuel Filter: Replace if clogged. Located inside fuel tank.
2. Fuel Lines: Inspect for cracks, brittleness, or leaks. Replace as a set.
3. Fuel Tank Vent: Ensure it is clear to prevent vacuum lock.
4. Carburetor: Walbro or Zama carburetor. See section 8 for adjustment.

Tip: Use a fuel stabilizer if storing the saw for more than 30 days.

Ignition System

Electronic ignition system includes flywheel, ignition module, spark plug, and stop switch.

1. Spark Plug: Gap should be 0.5 mm (0.020"). Replace if electrodes are worn or fouled.
2. Ignition Module: Check for spark by grounding plug against cylinder. No spark indicates faulty module.
3. Flywheel Key: Check if sheared, which will cause timing issues.
4. Stop Switch: Test continuity. Should be open when off, closed when on.

WARNING! Always disconnect spark plug wire before testing ignition system.

Chain & Bar Assembly

Proper chain and bar maintenance is critical for safety and performance.

1. Chain Tension: Adjust so chain snaps back when pulled from bar. Should not sag.
2. Bar Maintenance: File down burrs on bar rails. Rotate bar regularly for even wear.
3. Chain Sharpening: Use correct round file size. Maintain proper filing angle (typically 30°).
4. Sprocket: Inspect for wear. Replace if teeth are hooked or worn down.
5. Oil System: Ensure oiler port on bar is clear. Adjust oil flow as needed.

CAUTION! A loose chain can derail and cause serious injury.

Carburetor Adjustment

The carburetor has three adjustment screws: L (low speed), H (high speed), and LA (idle).

1. Initial Settings: Turn L and H screws clockwise until lightly seated, then back out 1 turn.
2. Idle Adjustment: Set LA screw so chain does not move at idle but engine runs smoothly.
3. Fine Tuning (Warm Engine): Adjust L for fastest idle, then rich slightly. Adjust H for max RPM, then rich slightly (4-stroking sound).
4. Final Check: Chain must not move at idle. Engine should accelerate smoothly.

WARNING! Incorrect H screw setting can cause engine damage due to lean running.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine will not start	No spark, flooded, fuel issue	Check spark, dry plug, clean carburetor, ensure fuel flow.
Engine starts then dies	Clogged fuel filter, carb adjustment	Replace fuel filter, adjust L screw, check tank vent.
Loss of power	Dirty air filter, clogged spark arrestor, carb adjustment	Clean/replace air filter, clean spark arrestor screen, adjust H screw.
Chain does not oil	Clogged oil port, faulty oil pump	Clean bar oil hole, check oil lines, replace oil pump if necessary.
Excessive vibration	Loose components, worn anti-vibration mounts	Tighten all fasteners, replace anti-vibration elements.
Chain keeps coming loose	Worn bar, stretched chain, improper tensioning	Inspect bar for wear, replace chain, properly tension chain.

Reset: For electronic ignition issues, module may need replacement.

Parts List & Diagrams

Genuine STIHL parts are required for optimal performance and safety. Refer to official STIHL 038 IPL (Illustrated Parts List) for part numbers and exploded views of:

• Cylinder & Piston Assembly
• Crankshaft & Bearings
• Carburetor & Fuel System
• Ignition System
• Chain Brake & Clutch Assembly
• Anti-Vibration System
• Guide Bar & Chain

Tip: Always note the serial number of your saw when ordering parts.

Warranty & Support

STIHL 038 chainsaws are backed by a limited warranty. Proof of purchase is required.

Warranty Coverage: Covers defects in materials and workmanship for a specified period from date of retail purchase. Does not cover normal wear, misuse, or lack of maintenance.

Service Support: For technical assistance, parts, or to locate an authorized STIHL service dealer:

• Visit: www.stihlusa.com
• Contact: 1-800-GO-STIHL (1-800-467-8445)

CAUTION! Repairs by unauthorized personnel may void the warranty.