Part of the New Holland Repair Manuals.
Whether your garden tractor runs the Kohler twin in a GT18 or GT22 or the Kawasaki engine in a GT20, this 740-page New Holland GT18, GT20, GT22 repair manual PDF covers all three in one book. Wiring diagrams trace each circuit from the battery through the fuses and relays, and hydraulic schematics lay out the flow behind the lift and power steering systems. Your rebuild work is here too: carburetor adjustments, governor linkage, hydrostatic transmission disassembly, PTO clutch testing, and mower deck service, right down to reassembly torques. Gap the spark plugs at 1.02 mm (0.040 in.), then seat the carburetor mounting fasteners at 9.9 N·m (88 in. lb.); both figures come straight off the factory pages. Every weekend the tractor sits is grass you are not cutting. The bookmarked, keyword-searchable file rides along on whatever screen is closest to the machine.
What's Inside This New Holland GT18, GT20, GT22 Repair Manual
| System | Pages | Key Topics |
|---|---|---|
| GT18 and GT22 Kohler Engines - General Information and Maintenance | 5-25 | Safety Information, Engine Identification, Oil Recommendations, Periodic Maintenance, Storage |
| GT18 and GT22 Kohler Engines - Air Intake and Fuel Systems | 26-45 | Air Cleaner Service, Fuel System Tests, Fuel Pump, Carburetor Disassembly, Carburetor Adjustments |
| GT18 and GT22 Kohler Engines - Governor, Lubrication, and Starter | 46-58 | Governor Linkage, Lubrication System, Oil Filter, Retractable Starter, Starter Rope Replacement |
| GT18 and GT22 Kohler Engines - Electrical and Disassembly | 59-83 | Spark Plugs, Battery Charging, Ignition System, Electric Starter, Starter Disassembly |
| GT18 and GT22 Kohler Engines - Engine Disassembly and Reconditioning | 84-121 | Disassembly Sequence, Cylinder Leakdown Test, Cylinder Head, Valves, Piston and Rings |
| GT18 and GT22 Kohler Engines - Reassembly | 122-158 | Reassembly Sequence, Closure Plate, Camshaft, Connecting Rods, Crankshaft |
| GT20 Kawasaki Engines - General Information and Specifications | 159-186 | General Information, Engine Specifications, Maintenance Chart, Torque Values, Fuel System |
| GT20 Kawasaki Engines - Cooling, Top End, and Lubrication | 187-252 | Cooling System, Engine Top End, Lubrication System, Oil Pump, Oil Screen Filter |
| Electrical | 321-456 | Component Location and Function, Battery, Fuses, Relays |
| PTO System | 457-470 | Description and Operation, Clutch Testing, Belt Adjustment |
| Hydrostatic Transmissions | 471-548 | Description of Operation, Transmission Disassembly and Reassembly, Troubleshooting |
| Hydraulics | 549-576 | Description and Operation, Hydraulics Overhaul, Testing |
| Steering and Front Axle | 577-640 | Manual Steering System, Manual Steering System Overhaul, Power Steering System, Front Axle |
| Lift Linkage | 641-658 | Description and Operation, Upper Lift Linkage, Lower Lift Linkage |
| Specifications | 659-674 | Maintenance Tables, Hardware Tightening Torques |
| Mower Decks | 675-740 | Gt18 and Gt22 Kohler Engines (Safety and General Information, Special Tools, Troubleshooting, Air Cleaner and Air Intake System, Fuel System and Governor, Lubrication System, Retractable Starter, Electrical System and Components, Disassembly, Reconditioning, Reassembly) |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Starter Mounting Fastener Torque | 15.3 N·m (135 in. lb.) | p. 17 |
| Oil Filter Torque | 5.7/9.0 N·m (50/80 in. lb.) | p. 18 |
| Carburetor Mounting Fasteners Torque | 9.9 N·m (88 in. lb.) | p. 16 |
| Spark Plug Gap | 1.02 mm (0.040 in.) | p. 18 |
| Spark Plug Torque | 24.4/29.8 N·m (18/22 ft. lb.) | p. 18 |
| Stopper Screw torque | 2.00 N-m (17.0 in-lb) | p. 167 |
| Starter motor commutator groove depth service limit | 0.2 mm (0.008 in.) | p. 18 |
| Clutch cap screw torque (GT20) | 40 N·m (35 ft.-lb.) | p. 458 |
| Clutch cap screw torque (GT22) | 67 N·m (50 ft.-lb.) | p. 458 |
| Steering Control Unit Nominal Flow Rating | 15 L/min (4 gal/min) | p. 639 |
| Steering Control Unit Inlet Pressure Rating | 69 bar (1000 psi) | p. 639 |
| In-line Filter Screen | 140 Micron | p. 639 |
New Holland GT18, GT20, GT22 Common Problems This Manual Covers
New Holland GT18 starter clicks but engine won't crank, battery reads fully charged
Test the battery under load first; the spec on page 328 calls for 12 volts and 380 cold cranking amps. Clean both cable ends and the frame ground to bright metal. If the solenoid clicks but nothing turns, pull the starter, bench test it, and remount with the fasteners torqued to 15.3 N·m (135 in. lb.).
Manual Section: Electrical p. 328Battery keeps going dead between mowings even after a full overnight charge
Check charging output at the battery posts with the engine at full throttle; if voltage never rises above resting, suspect the regulator. Charge the battery at 4 amperes or less for 4 hours per page 331, then load test it. Scrub the terminals and harness grounds; corroded grounds kill these charging circuits more often than alternators do.
Manual Section: Electrical p. 331Hydrostatic drive slows down or quits pulling after mowing an hour in summer heat
Check the transaxle oil level cold and change the transaxle filter if it's past the 200 hour interval listed on page 666. Blow the grass and chaff out of the hydro cooling fins and fan. Inspect the drive belt for glazing and correct tension; a slipping belt acts just like a worn pump once the oil heats up.
Manual Section: Hydrostatic Transmissions p. 471Power steering stiff and jerky, wheel kicks back when crossing rough ground
Grease the steering fittings every 50 hours, one pump each, and clean the power steering in-line screen (140 micron) at the 200 hour interval on page 666. Verify the steering control unit relief valve setting of 50 bar (725 psi) against page 639, and check tie rod ends and the axle pivot for slop before condemning the control unit.
Manual Section: Steering and Front Axle p. 639Engine surges at idle and stalls when the mower deck is engaged
Replace the fuel filter if it has more than 100 hours (interval on page 666) and drain stale gas from the tank and carburetor bowl. Check the governor linkage for binding. On the Kohler engines, follow the fuel system troubleshooting starting on page 26 and torque the carburetor mounting fasteners to 9.9 N·m (88 in. lb.) after any rework.
Manual Section: GT18 and GT22 Kohler Engines - Air Intake and Fuel Systems p. 26Electric PTO switch pulled but blades won't engage, no click from the clutch
Check for 12 volts at the clutch connector with the PTO switch pulled and the seat occupied. If voltage is present but the clutch stays silent, test the field coil for continuity using the procedure in the PTO section starting on page 457. Check belt tension; the schedule on page 667 calls for a tension check every 50 hours.
Manual Section: PTO System p. 457Frequently Asked Questions
What are the cylinder head fastener torque specs for the Kohler engines in the New Holland GT18 and GT22?
The final torque specification for the cylinder head fasteners on the Kohler engines is 40.7 N⋅m (30 ft. lb.). p. 17
How often should the oil filter be changed on the Kohler engines?
The oil filter should be changed every 200 hours of operation on the Kohler engines. p. 10
What is the correct spark plug gap for the Kohler engines in the New Holland GT18 and GT22?
The correct spark plug gap for the Kohler engines is 1.02 mm (0.040 in.). p. 18
What is the procedure for checking the crankcase vacuum on the Kohler engines?
Crankcase vacuum is measured using a water manometer (Kohler Part No. 25 800 50). With the engine running at no load high idle speed (3200 to 3750 RPM), the level in the engine side should be a minimum of 10.2 cm (4 in.) above the level in the open side. p. 28
What is the torque spec for the flywheel retaining screw on the Kohler engines in the New Holland GT18 and GT22?
The torque specification for the flywheel retaining screw on the Kohler engines is 66.4 N⋅m (49 ft. lb.). p. 18
How will I receive this New Holland GT18 Repair Manual?
All 740 pages arrive as one searchable PDF at checkout. Read it at the desk, then take the phone out to the machine.
Can I print a copy of this New Holland GT18 Repair Manual for the shop?
Printing is allowed without restriction. Pull the pages you need for the job and bin them when they get greasy.
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