The Toro Model 74327 is a commercial-grade zero-turn riding mower designed for professional landscaping and large property maintenance. This service manual provides comprehensive information for maintenance, troubleshooting, and repair procedures. It covers the 747cc Toro V-Twin OHV engine, 52-inch fabricated steel deck, Hydro-Gear ZT-3400 transaxles, electrical system, hydraulic system, and safety features. Below are key sections for safety, specifications, maintenance schedules, troubleshooting, and repair procedures.
Critical safety warnings and precautions for operating and servicing the Toro Model 74327.
| Hazard | Precaution |
|---|---|
| Rotating Blades | Always disengage PTO and wait for blades to stop before dismounting or servicing deck. |
| Hot Surfaces | Allow engine and muffler to cool before performing maintenance. |
| Fuel Handling | Refuel outdoors only, with engine off and cool. No smoking. |
| Electrical Shock | Disconnect battery negative cable before servicing electrical components. |
| Hydraulic Pressure | Relieve hydraulic pressure by moving control levers before disconnecting lines. |
| Tipping Hazard | Do not operate on slopes exceeding 15 degrees. Mow across slopes, not up and down. |
| Crushing Hazard | Use jack stands when working under machine; never rely on hydraulic jack alone. |
| Flying Debris | Always wear safety glasses when operating or servicing. |
| Carbon Monoxide | Operate only in well-ventilated areas; never in enclosed spaces. |
| Runover/Backover | Keep bystanders, especially children and pets, away from operating area. |
Follow this schedule to maintain optimal performance and longevity.
WARNING! Failure to follow maintenance schedule may void warranty and cause premature failure.
Procedures for maintaining and servicing the 747cc V-Twin engine.
Oil Change: Use SAE 10W-30 detergent oil (API classification SJ or higher). Capacity: 2.0 quarts (1.9L) with filter change.
Air Filter: Replace paper element every 100 hours; clean foam pre-cleaner every 25 hours.
Spark Plugs: Gap: 0.030 inches (0.76 mm). Torque: 18 ft-lbs (24 Nm). Replace every 500 hours.
Valve Clearance: Intake: 0.004-0.006 in (0.10-0.15 mm). Exhaust: 0.006-0.008 in (0.15-0.20 mm). Check every 500 hours.
Fuel System: Replace in-line fuel filter every 500 hours. Use fresh fuel; add fuel stabilizer for storage over 30 days.
Cooling System: Keep cooling fins and shrouds clean. Inspect fan belt for cracks and tension.
Service for Hydro-Gear ZT-3400 transaxles and hydraulic circuit.
CAUTION! Use only specified fluid. Contamination will damage transaxles.
Maintenance and adjustment of the 52-inch fabricated deck.
WARNING! Always disconnect spark plug wire before servicing deck or blades.
12-volt system schematic and component service.
| Component | Test/Service Procedure |
|---|---|
| Battery | Charge with 2-amp charger. Maintain 12.6V. Clean terminals; coat with dielectric grease. |
| Starter | Draw should not exceed 180 amps. Check solenoid engagement. |
| Alternator | Output: 15 amps at 3600 RPM. Check voltage regulator. |
| Safety Switches | Test seat switch, PTO switch, brake switch for continuity when activated. |
| Fuses | Main fuse: 20A. Access behind dash panel. Replace with same rating. |
| Wiring Harness | Inspect for chafing, especially near pivot points and hot surfaces. |
Tip: Use a multimeter for diagnosis. Refer to wiring diagram in Section 10.
Description of operator controls and proper operation.
Control Levers: Neutral lock-out must be disengaged to start. Move levers forward/reverse for direction and speed. To turn, move one lever toward neutral relative to the other.
PTO Engagement: Engage only at full throttle. Allow blades to reach full speed before moving.
Parking Brake: Set brake before dismounting. Brake automatically engages when control levers are moved fully outward.
Height of Cut: Adjust lever while deck is lowered. Mow at highest setting for tall grass, then lower.
Transport Mode: For towing, disconnect drive by pulling bypass rods on transaxles.
| Symptom | Possible Cause | Corrective Action |
|---|---|---|
| Engine cranks, won't start | Fuel, spark, air | Check fuel shut-off valve, spark plug, air filter. Verify safety switches. |
| Loss of power/hydraulic drive | Low fluid, air in system, belt | Check fluid level, bleed system, inspect drive belt for wear/slippage. |
| Uneven cut | Deck not level, dull blades, low tire pressure | Level deck, sharpen/balance blades, inflate tires to 14 PSI. |
| Excessive vibration | Damaged/bent blade, loose spindle, debris | Inspect and replace blade, tighten spindle bolts, clean deck. |
| Battery won't charge | Bad battery, faulty alternator, corroded terminals | Load test battery, check alternator output, clean terminals. |
| PTO won't engage | Blown fuse, faulty switch, bad clutch | Check 20A fuse, test PTO switch for continuity, test clutch coil resistance (3-5 ohms). |
| Unit pulls to one side | Control linkage out of adjustment, low tire | Adjust neutral on control linkage, check and equalize tire pressure. |
| Hydrostatic transmission overheats | Low fluid, dirty cooler, restricted airflow | Check fluid level and condition, clean cooler fins, ensure area is clear. |
Reset: For electronic issues, disconnect battery for 5 minutes to reset controller.
Key replacement part numbers for Toro Model 74327.
Note: Always verify part number with your serial number before ordering.
Toro Commercial 3-Year Warranty: Covers defects in materials and workmanship for 3 years from date of retail purchase for commercial use. Excludes normal wear items (belts, blades, filters, tires), damage from abuse, neglect, or improper maintenance.
For Technical Support & Parts:
Serial Number Location: Stamped on frame crossmember under the seat.
Copyright: © 2025 The Toro Company. All rights reserved. TORO is a registered trademark of The Toro Company.