The Stihl 038 is a professional-grade chainsaw known for its durability and power. This repair manual provides comprehensive instructions for maintenance, troubleshooting, and repair of the Stihl 038 series, including the 038 AV, 038 AV Super, and 038 Magnum models. It covers engine systems, fuel system, ignition, chain brake, lubrication, and electrical components. Below are key sections for safety, specifications, disassembly, repair procedures, and troubleshooting.
Before performing any repair, ensure the chainsaw is turned off, the spark plug wire is disconnected, and all pressure is released from the fuel system. Wear appropriate personal protective equipment (PPE).
| Hazard | Precaution |
|---|---|
| Fuel & Oil | Work in well-ventilated area; no smoking or open flames |
| Sharp Components | Wear cut-resistant gloves when handling chain, bar, or cutter teeth |
| Spring Tension | Use proper tools to disassemble chain brake; springs are under tension |
| Electrical Shock | Disconnect spark plug before working on ignition system |
| Hot Surfaces | Allow engine to cool completely before disassembly |
Identify your model via serial number plate on the rear handle or crankcase.
Standard and Stihl-specific tools needed for repair.
NOTE: Use genuine Stihl tools or equivalents to avoid damage.
Step-by-step procedure to disassemble the engine unit.
WARNING! Label all parts and fasteners; take photos during disassembly for reference.
Inspecting and servicing the cylinder and piston assembly.
Cylinder Inspection: Check for scoring, wear, or transfer. Measure bore diameter. Light honing may be done if within service limits.
Piston Inspection: Check ring grooves for wear; measure ring end gap. Replace if out of specification.
Replacement Parts: Use Stihl OEM or aftermarket kits matching your model (038, 038 Super, or 038 Magnum).
Carburetor, fuel lines, and tank service.
Tip: Always pressure-test fuel system for leaks after repair.
Testing and replacing ignition components.
| Component | Test Procedure | Specification |
|---|---|---|
| Spark Plug | Check gap; replace if fouled or worn | Gap: 0.5 mm (0.020 in) |
| Ignition Coil | Measure primary/secondary resistance with multimeter | Primary: 0.5-2.0 Ω; Secondary: 8-15 kΩ |
| Stop Switch | Continuity test; should open when pressed | Infinite resistance when engaged |
| Flywheel Magnets | Inspect for cracks or loss of magnetism | Replace if damaged |
Service procedures for the chain brake and centrifugal clutch.
Chain Brake Disassembly: Remove side cover, brake band, and spring. Clean all parts; replace band if worn more than 0.5mm. Lubricate pivot points.
Clutch Service: Remove clutch drum and shoes. Inspect shoes for wear; replace if lining is worn to rivets. Clean clutch drum interior; check for grooves.
Reassembly: Ensure brake spring is correctly tensioned; test function before use.
Oil pump and delivery system maintenance.
CAUTION! Use only Stihl chain oil or equivalent to prevent pump damage.
Final assembly and operational adjustments.
Run-in: Operate at varied speeds for first tank to seat new components.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Engine won't start | No spark, fuel, or compression | Check spark plug, fuel lines, carburetor, cylinder compression |
| Engine runs poorly | Clogged air filter, carb adjustment | Clean/replace filter; adjust H/L screws; check fuel filter |
| Loss of power | Exhaust clogged, air leak | Clean spark arrestor; pressure test crankcase for leaks |
| Chain doesn't oil | Clogged oil passages, pump failure | Clean bar oil hole; inspect oil pump and drive gear |
| Chain brake fails | Worn brake band, weak spring | Replace brake band and/or spring |
Service Support: For technical assistance or parts, contact Stihl authorized service or visit www.stihlusa.com.