Craftsman 18 Chainsaw Repair Manual

The Craftsman 18 Chainsaw is a gas-powered chainsaw featuring an 18-inch guide bar, 42cc 2-cycle engine, automatic oiler, chain brake, anti-vibration system, and tool-less chain tensioning. This manual provides essential information for safe operation, routine maintenance, troubleshooting, and repair procedures to ensure optimal performance and longevity of your chainsaw. Below are key sections covering safety, features, maintenance, repair, and troubleshooting.

Features at a Glance

Key components: 42cc 2-cycle engine, 18-inch guide bar and chain, automatic chain oiler, inertia-activated chain brake, anti-vibration handles, tool-less chain tensioner, primer bulb, and decompression valve.

Safety Precautions

Always wear appropriate personal protective equipment (PPE) including safety glasses, hearing protection, gloves, chainsaw chaps, and sturdy boots.

1. Inspect chainsaw before each use: Check for loose parts, chain sharpness, and proper chain tension.
2. Clear work area: Ensure no bystanders, pets, or obstacles within 15 feet.
3. Proper fueling: Use fresh fuel mix (50:1 gasoline to 2-cycle oil). Refuel in well-ventilated area, engine off and cool.
4. Secure workpiece: Never cut with the tip of the bar (avoid kickback).
5. Carry safely: Engage chain brake when moving between cuts.

WARNING! Failure to follow safety guidelines can result in serious injury or death. Always read and understand the operator's manual before use.

Parts Identification

Familiarize yourself with the main components for effective maintenance and repair.

1. Front Handle / Top Handle: Contains throttle trigger and throttle lockout.
2. Rear Handle: Contains start/stop switch and rear hand guard.
3. Engine Housing: Houses the engine, air filter, and muffler.
4. Guide Bar: The metal bar that guides the cutting chain.
5. Chain Sprocket: Drives the chain around the bar.
6. Chain Brake Lever / Hand Guard: Activates the chain brake.
7. Chain Tensioner Knob: Tool-less adjustment for chain tension.
8. Fuel Tank Cap & Oil Tank Cap: For refueling and refilling bar & chain oil.

CAUTION! Disconnect the spark plug wire before performing any maintenance or repair.

Specifications

• Engine Type: 2-cycle, single cylinder, air-cooled.
• Displacement: 42 cc (2.6 cu in).
• Power Output: Approximately 2.2 HP.
• Fuel: Unleaded gasoline (89 octane or higher) mixed with 2-cycle engine oil at 50:1 ratio.
• Bar Length: 18 inches (45 cm).
• Chain Pitch: 3/8-inch low-profile.
• Chain Gauge: 0.050 inches.
• Oil Tank Capacity: Approximately 8.5 fl oz (250 ml).
• Weight (dry): Approximately 10.8 lbs (4.9 kg).
• Ignition: Electronic (CDI).
• Spark Plug: Champion RCJ-6Y or equivalent, gap 0.025 inches.

Routine Maintenance

Regular maintenance is crucial for safety and performance. Perform these checks before and after each use.

Daily/Pre-Use: Check chain sharpness and tension, inspect bar for wear, check oiler function, clean air filter, inspect for loose nuts/bolts.

Weekly/Periodic: Clean spark arrestor screen, check fuel filter, clean cooling fins, inspect spark plug, check anti-vibration elements.

Cleaning: Use a brush to remove sawdust and debris from the air intake, cooling fins, and clutch area. Never use water or high-pressure air.

Chain & Bar Care

Proper chain and bar maintenance ensures efficient cutting and extends component life.

1. Chain Tension: Adjust when chain is cold. Lift the tip of the bar; chain should snap back against the bar rail. Adjust using the tool-less tensioner knob.
2. Chain Sharpening: Use a round file matching the chain pitch (5/32" for 3/8" low-profile). Maintain correct filing angle (typically 30°). File all cutters to equal length.
3. Bar Maintenance: Flip the bar weekly for even wear. Clean the bar groove and oil holes. Check for "burring" on the rails and file smooth if needed.
4. Oiler Function: Ensure automatic oiler is working. Chain should show a light spray of oil when running at full throttle off the wood.

Tip: Always use quality bar and chain oil. Never use waste oil.

Engine Troubleshooting

Common engine problems and initial checks.

1. Engine won't start: Check fuel (fresh 50:1 mix), spark plug (clean/gap), ignition switch (ON), choke/primer bulb operation, and decompression valve.
2. Engine starts then dies: Check fuel filter, carburetor settings (L/H screws), air filter (clean), and fuel tank vent.
3. Engine lacks power: Clean air filter and spark arrestor, check for clogged muffler, adjust carburetor, verify fuel mix.
4. Engine runs unevenly: Likely a carburetor issue requiring adjustment or cleaning.

WARNING! Allow engine to cool completely before troubleshooting or repair.

Carburetor Adjustment

The carburetor has three adjustment screws: L (Low speed), H (High speed), and T or LA (Idle speed).

1. Initial Settings (if rebuilt): Turn L and H screws gently clockwise until seated, then back out 1-1/4 turns each. Set idle screw so chain just does not move.
2. Warm up engine: Run at half throttle for 2-3 minutes.
3. Adjust idle: With chain brake OFF, adjust T/LA screw so engine idles smoothly and chain does not move.
4. Adjust L screw: From idle, accelerate quickly. If it hesitates, open L screw (counter-clockwise) slightly. If it "four-strokes" or smokes, close L screw slightly.
5. Adjust H screw: NEVER set too lean. With chain brake ON, open to full throttle. Adjust H screw for peak RPM, then richen slightly (turn clockwise about 1/8 turn) for a slight "four-stroking" sound at full throttle off load.
6. Re-check idle after adjustments.

CAUTION! An improperly adjusted H screw can cause engine damage due to lean running. Consult a professional if unsure.

Fuel System

Components: Fuel tank, cap/vent, fuel line, filter, primer bulb, carburetor.

Common Issues & Repair:

• Fuel Line Cracking: Replace with ethanol-resistant line. Disconnect from carburetor and tank, install new line.
• Fuel Filter Clogging: Replace annually or as needed. Access through fuel tank filler neck.
• Primer Bulb Failure: Bulb may crack or lose seal. Replace by removing carburetor cover and disconnecting fuel lines.
• Carburetor Diaphragm: Over time, diaphragms harden. Rebuild kit includes new diaphragms, gaskets, and needle valve.

Always use fresh fuel mix (less than 30 days old) to prevent varnish buildup.

Ignition System

Components: Flywheel, ignition coil (CDI module), spark plug, stop switch wire.

Troubleshooting Steps:

1. Check Spark: Remove spark plug, reconnect boot, ground plug base against cylinder. Pull starter cord; look for bright blue spark.
2. No Spark: Check plug condition and gap (0.025"). Replace if fouled or cracked.
3. Still No Spark: Check stop switch wire for continuity/disconnect it to test. Check air gap between ignition coil and flywheel (0.010" / 0.25 mm).
4. If still no spark, the CDI module may be faulty and require replacement.

Tip: Keep the flywheel fins and cooling fins clean for proper engine cooling.

Troubleshooting Guide

Reset: For electronic ignition modules, disconnecting the spark plug wire does not reset. Refer to specific module instructions.

Service: For technical support or genuine Craftsman parts, contact 1-888-331-4569 or visit www.craftsman.com.