Gehl built this shop manual (OEM #904167) to take a stalled skid loader back to factory spec, and its 114 pages stay on that task. The hydraulic schematics trace the full hydrostatic circuit plus the lift and tilt system, backed by a complete electrical diagram and 50 pages of rebuild and adjustment steps for the tandem pump, brake cables, and axle assemblies. Seven pages of troubleshooting charts split the hydrostatic, hydraulic, and electrical systems apart, so you diagnose with Gehl's own logic instead of forum guesswork. Set fan belt deflection, then confirm the reservoir holds its full 18 gallons (68 liters) before you fire the system up. Stop chasing ghosts with a multimeter. Every page is bookmarked and keyword-searchable, opening on whatever device you carry out to the machine.
What's Inside This Gehl SL6620, SL6625 Manual
| System | Pages | Key Topics |
|---|---|---|
| Specifications | 6 | General (Model & Description, Sae Operating Capacity, Sae Tip-Up Capacity, Machine Weight, Volumetric Capacities & Deliveries, Hydraulic System Filtration, Travel Speed, Controls, Brakes, ROPS, Electrical System, Tire Size & Pressure, Flotation, Overall Height, Overall Height with Operator Guard, Ground Clearance, Overall Length, Overall Length Less Bucket, Wheel Base, Dump Reach, Rollback at Ground, Dump Angle, Overall Width, W/8.25 X 15 Tires, W/12.00 X 16.5 Tires) |
| Safety | 7-8 | Safety Alert Symbol Meaning, Operator Responsibilities and Pre-Operation Checks |
| Decals | 9-14 | New Decal Application, Decal Locations |
| Lubrication | 15-16 | Oils, Chaincases, Engine Crankcase, Hydraulic Oil Reservoir, Planetary Gearcase, Greasing, Engine Oil Viscosity Index, Hydrostatic Oil Viscosity Index |
| Chassis | 17-28 | Description, Overhead Guard, In-Seat Safety Switch-Before S.N. 2651, In-Seat Safety Switch-After S.N. 2650, Seat, Restraint Bar Switch, Lift Arm Assembly, Attachment Assembly |
| Drive | 29-46 | Brakes, Disc Brake Adjustment, Brake Pad Replacement, Brake Cables, Traction Drive T-Bar, Neutral Adjustment, Servo Adjustment, Take-Up Rods |
| Hydrostatic System | 47-66 | Introduction, Neutral, Forward, Reverse, Turns, Troubleshooting, Hydrostatic Testing, Drive Motor |
| Hydraulic System | 67-96 | Introduction, Cylinders, Hydraulic Hoses and Tubing, Electrical Components, Troubleshooting, Hydraulic Testing, Control Valve Relief Pressure, Lift and Tilt System Pump |
| Electrical System | 97-98 | Troubleshooting: Start Will Not Crank, Troubleshooting: Battery Will Not Recharge, Troubleshooting: Entire Electrical System Does Not Function |
| Engine | 99-114 | Engine Oil Filter, Air Cleaner, Battery, Starter, Engine Exhaust Assembly, Fan Belt Adjustment |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Wheel Nuts Torque | 150 ft. lbs. | p. 57 |
| Fan Belt Deflection | 1/4 inch (with 4 pound force applied) | p. 99 |
| Hydraulic System Reservoir Capacity | 18 gallon (68 liter) | p. 6 |
| Hydraulic Pump Relief Pressure | 2500 PSI (172 bar) | p. 6 |
| Engine Oil Capacity | 6-1/3 U.S. quarts (6 liters) | p. 6 |
| Engine Coolant Capacity | Approx. 12 qts. | p. 6 |
| Hydrostatic Charge Pressure | 240 PSI | p. 48 |
| Control Valve Relief Pressure | 2450 and 2550 PSI | p. 65 |
| Lubrication Interval (Daily) | Every 10 hours | p. 15 |
| Lubrication Interval (Axle Bearing) | Every 500 hours | p. 15 |
| SL6620 | ||
| Operating Capacity | 2050 lb (930 kg) | p. 6 |
| SL6625 | ||
| Operating Capacity | 2250 lb (1020 kg) | p. 6 |
Gehl SL6620, SL6625 Common Problems This Manual Covers
Gehl SL6620/SL6625 hydraulics stop working mid-cycle, lift arm won't raise p. 67
Check the hydraulic fluid level first; the reservoir holds 18 gallons (68 liters), so top it off if it reads low. Next, inspect the pump drive coupler between the engine and hydraulic pump for cracking or stripping, since a failed coupler is the usual reason these machines lose all hydraulic power at once. With fluid and coupler both good, look for a clogged filter and confirm system relief pressure reads 2500 PSI (172 bar) per the page 6 specs. Work through the full sequence on page 67.
Manual Section: Hydraulic SystemEngine turns over but won't start, or starts then dies immediately p. 94
Verify battery terminals are tight and the battery is holding charge; a weak battery won't sustain glow plug draw in cold weather. If the engine spins freely but won't fire, follow the start sequence in the Engine Troubleshooting section beginning on page 94.
Manual Section: EngineDrive response is sluggish or machine pulls hard to one side p. 45
Inspect the hydrostatic neutral adjustment on both sides; a drive circuit out of neutral will pull the machine to that side. Confirm charge pressure sits at 240 PSI (page 48), because low charge pressure shows up as sluggish or asymmetric drive. Check the traction drive T-bar linkage and take-up rods for looseness or binding, then work through the full drive troubleshooting matrix starting on page 45.
Manual Section: DriveFan belt squealing, slipping, or engine overheating at operating temperature p. 100
Measure belt deflection: a belt that runs too loose slips under load and lets the cooling fan lag. Check coolant level against the 12 qt. capacity (page 6), then clear any debris packed against the radiator face, since these machines pull chaff and dirt fast. Belt adjustment procedure is in the Engine section starting page 100.
Manual Section: EngineJoystick controls feel jerky, delayed, or lift arm action is erratic p. 67
Examine each joystick wiring connector for corrosion or loose pins, since vibration works them loose over time. Check the safety switches: the seat switch and restraint bar switch must both close before the controls will operate. If wiring and switches are sound, confirm hydraulic relief pressure falls within the 2450-2550 PSI range (page 65); pressure below that produces the jerky, inconsistent cylinder action you're seeing. Hydraulic System Troubleshooting starts page 67.
Manual Section: Hydraulic SystemEntire electrical system dead, no gauges, lights, or starter response p. 91
Start at the battery: check the terminals for corrosion and read voltage under load. Trace the main fuse and ground connections at the chassis, because a single failed ground can knock out the whole panel. The electrical troubleshooting sequence on page 91 covers no-start, battery-not-recharging, and total system failure in that order. Inspect the starter connections at the solenoid before condemning the starter itself.
Manual Section: Electrical SystemFrequently Asked Questions
What are the torque specs for GEHL SL6620/SL6625 wheel or hydraulic components?
Both the Slotted Axle Nut and the Wheel Nuts torque to 150 ft. lbs. Pump pivot arm cap screws take 35-40 ft. lbs. Installing the valve block to the housing calls for a cross torque of 42-45 ft. lbs. on the CS, while O-rings on the tandem pump valve block plugs go to 128-148 ft. lbs. Planetary gearcase to chassis bolts need 90 ft. lbs. if plated or 120 ft. lbs. if unplated; the original 9/16" x 18" plated bolts torque to 130 ft. lbs., or 170 ft. lbs. unplated.
How to troubleshoot a no-start condition on a GEHL SL6620/SL6625?
Start with the main 30 ampere fuse: if it's blown, work the circuit against the wiring diagram before replacing it. Make sure battery connections are tight and clean and the battery is charged, replacing it if it's defective. Check that the starter solenoid, starter, and starter relay all function. Confirm the driver is seated with the restraint bar down, and look for loose or disconnected wiring at the ignition, seat switch, and restraint bar switch. If the engine turns over but won't fire, check the fuel level and the fuel shut-off solenoid, and make sure engine and fuel are warm enough, using the glow plugs when needed.
Is this Gehl SL6620, SL6625 Shop Manual a digital download?
Yes, it's an instant PDF download. The full 114-page searchable Shop Manual lands in your hands right after payment, ready to open on a laptop, tablet, or phone out in the shop.
Can I print this Gehl SL6620, SL6625 manual?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
Can I find hydraulic circuit diagrams in this Gehl SL6620, SL6625 manual?
Full hydraulic system diagrams are included, covering circuits, valve locations, and hydraulic component specs for the Gehl SL6620, SL6625.
Document Quality
This is a scanned PDF document with an OCR layer, so you can search and copy text. The text is generally crisp and readable, though some smaller fonts show minor scanning artifacts. Diagrams and illustrations are scanned images, which are mostly clear but can pixelate at high zoom, with labels remaining readable. Pages are clean with occasional slight skew and background discoloration. Several blank pages are present throughout the document.
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