Husqvarna YTH18542 Repair Manual

The Husqvarna YTH18542 is a 42-inch riding lawn mower featuring a Briggs & Stratton engine, hydrostatic transmission, electric PTO clutch, and a durable steel frame. This manual provides comprehensive repair, maintenance, and troubleshooting guidance for owners and technicians. Below are key sections covering safety, specifications, engine service, drive system, electrical, deck maintenance, and common repairs.

Features at a Glance

Key components: Briggs & Stratton single-cylinder engine, Hydrostatic transmission, 42-inch stamped steel mower deck, Electric PTO clutch, 12V battery, Manual blade engagement, Adjustable cutting height, Comfort high-back seat.

Safety Precautions

Always follow safety procedures before performing any repair or maintenance.

1. Disconnect spark plug wire before working on engine or blades.
2. Engage parking brake and block wheels when lifting.
3. Allow engine to cool before servicing fuel system.
4. Use jack stands; never rely solely on hydraulic jack.
5. Wear safety glasses and gloves.

WARNING! Rotating blades can cause severe injury. Ensure mower is off and blades are stopped before any deck service.

Specifications

• Model: YTH18542
• Engine: Briggs & Stratton 40N877, 18.5 HP, 540cc
• Oil Capacity: 1.5 quarts (SAE 30 or 10W-30)
• Transmission Fluid: Husqvarna Hydrostatic Fluid (approx. 4.5 quarts)
• Blade Length: 21 inches each (2 or 3 blades depending on deck)
• Tire Size: Front 15x6.00-6, Rear 20x10.00-8
• Weight: Approx. 500 lbs
• Max Speed: Forward 5.5 mph, Reverse 2.2 mph

Engine Service & Maintenance

Regular engine maintenance ensures longevity and performance.

1. Oil Change: Every 50 hours or seasonally. Drain plug underneath engine.
2. Air Filter: Check every 25 hours. Replace if dirty.
3. Spark Plug: Gap 0.030 inches. Replace annually.
4. Fuel Filter: In-line filter; replace if clogged.
5. Carburetor Adjustment: Idle speed screw and mixture screws as needed.
6. Valve Clearance: Check every 300 hours (intake 0.005-0.007 in, exhaust 0.007-0.009 in).

CAUTION! Use correct oil type. Overfilling can cause engine damage.

Drive System & Transmission

Hydrostatic transmission provides smooth speed control.

1. Drive Belt Replacement: Release tensioner, remove old belt, route new belt per diagram.
2. Transmission Fluid Change: Every 500 hours. Drain plug on transmission housing.
3. Neutral Adjustment: Adjust linkage if mower creeps when pedal is released.
4. Axle & Bearings: Check for play; replace if worn.

Tip: Always relieve belt tension before removal to prevent damage.

Electrical System & Wiring

12V system with key ignition, safety switches, and electric PTO.

1. Battery Testing: Use multimeter; should read 12.6V fully charged.
2. Starter Motor: Check solenoid and connections if engine doesn't crank.
3. Charging System: Test alternator output (approx. 13.5-14.5V when running).
4. Safety Switches: Seat, brake, and PTO switches must engage for starting.
5. PTO Clutch: Test resistance (typically 2-4 ohms). Replace if burned out.

WARNING! Disconnect battery negative terminal before electrical repairs.

Mower Deck & Cutting System

42-inch deck with three spindles and blades.

1. Blade Removal: Use blade holder to secure; remove bolt (usually 5/8" or 15/16").
2. Deck Leveling: Adjust lift links to ensure even cut.
3. Belt Replacement: Deck drive belt routes around pulleys and tensioner.
4. Spindle Bearing: Grease zerks every 25 hours. Replace if noisy or loose.
5. Deck Wash Port: Connect hose to clean underside after use.

CAUTION! Always balance blades after sharpening to prevent vibration.

Controls & Adjustments

Steering, brake, and pedal adjustments for optimal operation.

Steering: Adjust tie rods for alignment. Brake: Adjust cable if parking brake doesn't hold. Pedals: Free play should be 1/4 to 1/2 inch. Cutting Height: Adjust lever positions for desired height.

Lubrication & Fluid Service

Regular lubrication reduces wear.

1. Engine Oil: SAE 30 (above 32°F) or 10W-30 (variable temps).
2. Transmission Fluid: Husqvarna Hydrostatic Fluid or equivalent.
3. Grease Points: Spindle zerks, pedal pivots, steering linkage (every 25 hours).
4. Fuel Stabilizer: Add for storage to prevent varnish.

Tip: Check fluid levels before each use.

Storage & Off-Season Care

Proper storage prevents issues when season starts.

1. Drain or stabilize fuel.
2. Change oil and filter.
3. Remove battery; store fully charged in cool place.
4. Clean deck thoroughly; lubricate all points.
5. Store in dry, covered area.

CAUTION! Never store with fuel in carburetor; it can clog jets.

Troubleshooting & Diagnostics

Reset: Disconnect battery for 10 minutes to reset electrical system if needed.

Service Support: 1-800-487-5952; www.husqvarna.com/us/support