STIHL 018 Chainsaw Repair Manual

The STIHL 018 is a lightweight, professional-grade chainsaw designed for demanding cutting tasks. This repair manual provides comprehensive information for maintenance, troubleshooting, and repair of the STIHL 018 chainsaw, including its engine, fuel system, ignition, chain brake, guide bar, and cutting chain. Below are key sections covering safety, specifications, maintenance procedures, troubleshooting, and parts identification.

1. Safety Precautions 2. Specifications & Technical Data 3. Maintenance Schedule 4. Engine Repair 5. Fuel System 6. Ignition System 7. Chain Brake & Clutch 8. Guide Bar & Cutting Chain 9. Troubleshooting Guide 10. Parts Diagram & List 11. Warranty & Service

Safety Precautions

Before performing any maintenance or repair, always disconnect the spark plug boot to prevent accidental starting. Wear appropriate personal protective equipment (PPE).

Hazard	Precaution
Fuel handling	Work in well-ventilated area; no smoking or open flames
Sharp components	Wear cut-resistant gloves when handling chain or bar
Hot surfaces	Allow engine to cool before servicing
Electrical shock	Disconnect spark plug before working on ignition
Chemical exposure	Use gloves when handling fuel, oil, or solvents

Specifications & Technical Data

Key technical specifications for the STIHL 018 chainsaw.

Engine Type: Single-cylinder, two-stroke, air-cooled.
Displacement: 31.8 cc (1.94 cu. in.).
Power Output: 1.8 kW (2.4 hp) at 9,500 rpm.
Fuel/Oil Mix: 50:1 (STIHL HP Ultra or equivalent).
Guide Bar Lengths: 12" to 16" (30 cm to 40 cm).
Chain Pitch: 3/8" PMM or .325".
Ignition: Electronic, breakerless.
Weight (powerhead): 4.2 kg (9.3 lbs).

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

Daily: Check chain tension, sharpness, and lubrication. Clean air filter.
Weekly: Inspect spark plug, fuel filter, and bar/chain wear.
Monthly: Clean cooling fins, check clutch drum and sprocket.
Annually: Replace fuel line, inspect carburetor diaphragm, check all screws/tightness.

WARNING! Always use genuine STIHL parts for replacement to maintain performance and safety.

Engine Repair

Common engine-related repairs: cylinder/piston inspection, carburetor adjustment, decompression valve.

Remove muffler to inspect piston/cylinder for scoring.
Adjust carburetor (LA, H screws) using tachometer per STIHL specifications.
Test compression: minimum 110 psi for proper operation.
Replace crankshaft seals if engine runs lean or has air leaks.

CAUTION! Engine components are precision parts; handle with care to avoid damage.

Fuel System

Fuel system components: tank, filter, lines, carburetor (Walbro or Zama).

Drain old fuel before storage or carburetor work.
Replace fuel filter annually or if clogged.
Clean carburetor: disassemble, soak in solvent, blow out passages.
Inspect fuel lines for cracks; replace if hardened or leaking.

Tip: Use only fresh, ethanol-free fuel mix to prevent carburetor issues.

Ignition System

Electronic ignition module, spark plug, stop switch, wiring.

Check spark: remove plug, ground to cylinder, pull starter—look for bright blue spark.
Test ignition coil resistance: primary 0.5-2.0 Ω, secondary 8-15 kΩ.
Inspect flywheel key; if sheared, replace and retime.
Ensure stop switch wire is not grounded when in "run" position.

WARNING! High voltage from ignition coil can cause shock. Handle with insulated tools.

Chain Brake & Clutch

Band-type chain brake, centrifugal clutch, drum, and sprocket.

Test brake function: with saw off, push handle forward—band should engage.
Replace brake band if worn or damaged.
Inspect clutch shoes for wear; replace if grooved or below spec.
Lubricate clutch bearing with high-temperature grease.

CAUTION! Never operate saw with faulty chain brake—risk of serious injury.

Guide Bar & Cutting Chain

Maintain bar rails, sprocket nose, and chain sharpness.

File bar rails flat if burred; dress sprocket nose regularly.
Rotate bar 180° weekly for even wear.
Sharpen chain with correct file size (typically 5/32" or 3/16").
Adjust depth gauges (rakers) after several sharpenings.

Tip: Keep chain properly tensioned—should snap back when pulled from bar.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine won't start	No spark, flooded, fuel issue	Check spark, dry plug, clean carburetor, fresh fuel.
Engine runs then dies	Clogged fuel filter, vent	Replace filter; check tank vent.
Poor cutting performance	Dull chain, low bar oil	Sharpen chain; check oiler output.
Excessive vibration	Unbalanced chain, loose parts	Balance chain; tighten mounting nuts.
Chain won't stop spinning	Clutch stuck, brake failed	Clean clutch; replace brake band.

Parts Diagram & List

Refer to STIHL part numbers for ordering replacements. Common parts:

Cylinder: 1110 020 1205
Piston: 1110 030 2001
Carburetor Kit: 1110 007 1050
Ignition Module: 1110 400 1300
Chain Brake Band: 1118 650 7701

Note: Always verify part numbers with your serial number.

Warranty & Service

STIHL limited warranty applies to original purchaser. For service, contact authorized STIHL dealers.

Support: Visit www.stihlusa.com or call 1-800-467-8445 for dealer locator and technical assistance.

Disclaimer: Repairs may require specialized tools; consult professional if unsure.