Part of the John Deere Repair Manuals.
John Deere's TM1678 strips the F620, F680, and F687 Z-Trak mowers down to the frame and builds them back, and this John Deere F620, F680, F687 technical manual PDF hands you all 366 pages of it. Electrical schematics and harness drawings claim roughly a third of the book, tracing every circuit from key switch to PTO clutch with diagnosis routines for each one. The hydrostatic power train gets its own hydraulic schematic plus pump rebuild and wheel motor repair procedures, and the Kohler CH20S and CH23S engine section runs from governor linkage to starting motor. Check PTO drive speed against the 3300 rpm spec, then torque the PTO clutch cap screw to 136 N-m (100 lb-ft). A number guessed off a forum can crack a clutch housing. Bookmarked and searchable by keyword, with serial number locations up front so your parts counter pulls the right numbers the first time.
What's Inside This John Deere F620, F680, F687 Manual
| System | Pages | Key Topics |
|---|---|---|
| General Specifications | 9-19 | Vehicle Specifications, Metric Fastener Torque Values, Metric Fastener Torque Values Grade 7, Inch Fastener Torque Values |
| Gasoline Specifications | 20-21 | 4-Cycle Engines North America, Gasoline Storage, 4-Cycle Engines Europe |
| Oils and Lubricants | 22-28 | 4-Cycle Gasoline Engine Oil North America, 4-Cycle Gasoline Engine Oil Europe, Break-In 4-Cycle Gasoline Engine Oil North America, Break-In 4-Cycle Gasoline Engine Oil Europe |
| Serial Number Locations | 29-30 | Machine Identification Number, Engine Serial Number, Mower Deck Serial Number |
| Engine (Kohler CH20S and CH23S) | 31-106 | Engine Specifications, Troubleshooting, Tests and Adjustments, Repair, Starting Motor |
| Electrical | 107-228 | Electrical Schematics, Wiring Harnesses, Circuit Operation, Diagnosis, Battery Test |
| Hydrostatic Power Train | 229-274 | Hydraulic Circuit Symbols, Power Train Operation, Troubleshooting, Hydraulic Pump Repair, Wheel Motor Repair |
| Brakes | 275-294 | Brake System Operation, Troubleshooting, Park Brake Adjustment, Disc Brake Repair, Drum Brake Repair |
| Attachments and Index | 295-366 | Mower Deck Troubleshooting, Mower Leveling, Gearbox Repair, Spindle Assembly, Index |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| PTO Drive Speed | 3300 ± 50 rpm | p. 12 |
| Engine Mounting Cap Screw (Bracket-to-Frame) Torque | 32 N•m (24 lb-ft) | p. 35 |
| Oil Filter Torque | 7.3 ± 1.7 N•m (65 ± 15 lb-in.) | p. 35 |
| Oil Drain Plug Torque | 13.6 N•m (10 lb-ft) | p. 35 |
| PTO Clutch Cap Screw Torque | 136 N•m (100 lb-ft) | p. 297 |
| Mower drive belt tension spring length | 133 mm (5.25 in.) | p. 312 |
| Engine Oil Capacity (With Filter) | 1.9 L (2.0 qt) | p. 11 |
| Hydraulic Oil Reservoir Capacity | 5.7 L (1.5 gal) | p. 12 |
| Spark Plug Gap | 1.02 mm (0.040 in.) | p. 35 |
| Flywheel Retaining Cap Screw Torque | 66.4 N·m (49 lb-ft) | p. 36 |
| F620 | ||
| Fuel Tank Capacity (F620) | 17 L (4.5 gal) | p. 12 |
| F680 and F687 | ||
| Fuel Tank Capacity (F680 and F687) | 26.5 L (7 gal) | p. 12 |
John Deere F620, F680, F687 Common Problems This Manual Covers
John Deere F620 PTO clutch slips and deck blades bog down in heavy grass
Check the deck drive belt first; a glazed or stretched belt mimics clutch slip, and the tension spring should measure 133 mm (5.25 in.) as shown on page 312. If the belt checks out, test voltage at the clutch connector, then retorque the clutch cap screw to 136 N·m (100 lb-ft) per page 297.
Manual Section: Attachments and Index p. 312Engine cranks but will not start, or pops and backfires through the carburetor
Verify fresh fuel and spark first. Remove both plugs, inspect for fouling, and regap to 1.02 mm (0.040 in.) per the specs on page 56. If it fires then dies, work through the fuel shutoff solenoid and carburetor checks in the troubleshooting charts starting, and set slow idle to 1200 ± 75 rpm once it runs.
Manual Section: Engine (Kohler CH20S and CH23S)Machine creeps forward in neutral or pulls to one side with both levers even
Check the hydraulic oil level before touching any adjustments; the reservoir holds 5.7 L (1.5 gal), spec on page 12. Low or aerated oil makes one pump lag and the machine wander. If the level is right, follow the neutral creep and tracking procedures in the hydrostatic power train section beginning on page 229; worn drive pump dampeners cause creep too.
Manual Section: Hydrostatic Power Train p. 229Everything goes dead at the key, or safety switches cut the engine over bumps
Check the main fuse and battery cable ends before blaming a harness. Load test the battery; it must meet the cold cranking rating for your model at -18°C (0°F), listed on page 109. Then wiggle test the connectors under the seat suspension while it runs, and trace the power circuit with the wiring diagram.
Manual Section: Electrical p. 109Engine knocks under load, blows blue smoke, or burns oil between mowings
Check oil level and condition first; these Kohler twins hold 1.9 L (2.0 qt) with a filter change, per page 11. Milky or gas-thinned oil wipes out rod bearings fast. Change oil, torque the drain plug to 13.6 N·m (10 lb-ft), and run the engine troubleshooting checks before pricing a rebuild.
Manual Section: Engine (Kohler CH20S and CH23S)Frequently Asked Questions
What is the engine oil capacity for the F620 and F680 engines?
The engine oil capacity for the F620 and F680 engines is 1.9 L (2.0 qt) when including the filter. p. 11
What is the torque spec for the PTO clutch retainer screw on a John Deere F620, F680, F687 Z-Trak mower?
The PTO clutch retainer screw on the engine must be tightened to 136 N•m (100 lb-ft). p. 35
What is the correct spark plug gap for the Kohler engines on a John Deere F620, F680, F687 Z-TRAK mower?
The correct spark plug gap for the Kohler engines is 1.02 mm (0.040 in.). p. 35
What is the torque spec for the cylinder head cap screws or nuts on a John Deere F620, F680, F687 Z-Trak mower?
The cylinder head cap screws or nuts should be tightened to an initial torque of 20 N•m (15 lb-ft) and a final torque of 40.7 N•m (30 lb-ft). p. 37
What is the procedure for adjusting the mower deck drive belt tension on 60-inch and 48/54-inch (S.N. 015001—) decks?
To adjust the belt tension, loosen the tension bracket pivot lock nut and slot lock nut, then turn the adjustment lock nut until the spring length measures 133 mm (5.25 in.). p. 312
Is this John Deere F620 manual a PDF I download?
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Yes, print as many copies as you want, and there are no restrictions. Many mechanics print the section they need and bring it to the shop floor.
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