This 145-page manual (OEM #917292) covers one machine family: the Tier 3 Yanmar-powered Gehl Mustang 2066, 2076, 2086, Gehl 5640E, and 6640E skid-steer loaders. It carries hydraulic and hydrostatic schematics for both dual-joystick and hand/foot control variants, full wiring schematics across the ROPS, chassis, and engine circuits, and 43 pages of step-by-step procedures. Another 12 pages of troubleshooting walk the hydrostatic, hydraulic, and electrical systems, while 30 pages of exploded views detail every mainframe, control, and lift-arm assembly. On service intervals: the hydraulic reservoir takes exactly 16 U.S. gallons (61 L) of ISO VG46-compliant fluid, changed every 500 hours or annually. When your machine is down, open the bookmarked PDF on any device, jump to the section you need, and get moving again.
What's Inside This Gehl Mustang 2066 & variants Manual
| System | Pages | Key Topics |
|---|---|---|
| Specifications | 7-8 | Dimensional Specifications |
| Safety | 9-16 | Signal Words, Additional Safety Reminders, Mandatory Safety Shutdown Procedure, Liftarm Support Device, Liftarm Support Device Engagement, Liftarm Support Device Disengagement |
| Lubrication | 17-20 | Crankcase Oil, Hydraulic Oil Reservoir, Chaincases, Cooling System Drain Procedures, Grease Fitting Locations |
| Mainframe | 21-38 | Introduction, Rollover and Falling Object - Protective Structure Components, Engine Access Cover, Chassis Components, Control Cover Components - Hand and Foot |
| Controls | 39-52 | Introduction, Lift and Tilt Components - Hand/Foot Control Models, Lift and Tilt Components - Dual Joystick and T-Bar/Joystick Control Models |
| Hydrostatic System | 53-64 | Hydrostatic System - Single-Speed Components - Dual Joystick Controls, Hydrostatic System - Single-Speed Components - T-Bar, T-Bar/Joystick and Hand/Foot |
| Hydraulic System | 65-88 | Introduction, Troubleshooting Guide, Standard Auxiliary Hydraulics - Dual Joystick, H/F and T-Bar/Joystick Controls, Standard Auxiliary Hydraulics - T-Bar Controls |
| Electrical System | 89-113 | Introduction, Operation - Right and Left Instrument Panels, Troubleshooting Guide, Chassis Electrical Components, ROPS Electrical Components |
| Engine | 114-137 | Introduction, Troubleshooting Guide, Engine Components - Yanmar 4TNV98 - 2066/76/86, Air Cleaner and Exhaust Components - 2066 |
| Back Cover | 145 | Gehl Company Information, Copyright Information, Printed in Usa |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Hydraulic filter replacement condition | when the restriction indicator shows red | p. 18 |
| Hydraulic filter tightening procedure | Hand tighten element until gasket contacts filter head. Turn element another 3/4 turn to seat gasket. | p. 79 |
| Hydraulic oil type | Mobil DTE 15M, or Petro-Canada Premium HVI60, or equivalent that contains anti-rust, anti-foam, and anti-oxidation additives & conforms to ISO VG46 or ISO VG48 | p. 17 |
| Hydraulic oil capacity | 16 U.S. gallons (61 L) | p. 17 |
| Engine Oil Capacity | 11.8 U.S. qts. (11,2 L) | p. 7 |
| Fuel Tank Capacity | 24 U.S. gal (91 L) | p. 7 |
| Chaincase Capacity (each) | 9 U.S. qts. (8,5 L) | p. 7 |
| Hydraulic Reservoir Capacity | 16 U.S. gal. (61 L) | p. 7 |
| Engine Coolant Capacity | 12 U.S. qts. (11,4 L) | p. 7 |
| Battery CCA | 950 CCA | p. 7 |
| Alternator Output | 95 A | p. 7 |
| Hydraulic System Pressure | 3000 psi (207 bar) | p. 7 |
Gehl Mustang 2066 & variants Common Problems This Manual Covers
Mustang 2076 hydraulic pump feels weak, travel sluggish, boom lifts slowly under load p. 58
Check hydraulic reservoir level first; it holds 16 U.S. gal. (61 L) and low oil is the most common cause on these machines. Inspect the suction line for kinks or collapse. Pull the return filter and check for metal contamination. Follow traction drive diagnostics on page 58 to isolate pump, motor, or valve fault.
Manual Section: Hydrostatic System Troubleshooting GuideMachine won't travel in one direction, opposite track drives normally on level ground p. 58
Inspect both chaincase oil levels; each side holds 9 U.S. qts. (8.5 L) and a low chaincase can mimic a drive circuit fault. Check drive hoses on the weak side for internal collapse under load. Use the directional drive fault chart on page 58 to narrow the fault to pump, wheel motor, or control valve.
Manual Section: Hydrostatic System Troubleshooting GuideLift arms drift down after releasing controls, bucket won't hold position under weight p. 65
Verify the lift control is not set to float, which allows free lowering. Inspect lift cylinder hoses and rod seals for external leaks. Check that system pressure holds at 3000 psi (207 bar) with the arms loaded. Review lift arm hold diagnostics on page 65 to identify valve seat leakage or worn seals.
Manual Section: Hydraulic System Troubleshooting GuideEngine cranks but won't fire, or turns over very slowly on cold mornings p. 114
Test the battery charge first; spec is 950 CCA and cold cranking draws every amp it has. Check that the fuel tank has sufficient fuel (24 U.S. gal. / 91 L capacity) and the shutoff valve is open. Inspect the fuel filter for restriction and confirm glow plugs cycle. Follow no-start diagnostics on page 114.
Manual Section: Engine Troubleshooting GuideHydraulic filter restriction indicator turned red, performance sluggish during repeated work cycles p. 18
Replace the hydraulic filter as soon as the restriction indicator shows red (page 18). Hand-tighten the new element until the gasket contacts the filter head, then turn another 3/4 turn to seat it (page 79). Change hydraulic oil every 500 hours or annually, and use ISO VG46 or ISO VG48 fluid with anti-rust and anti-foam additives.
Manual Section: LubricationHydraulic system overheats during repeated lift and dig cycles, temp warning keeps activating p. 58
Begin with the hydraulic reservoir level and oil condition; degraded or contaminated oil loses heat capacity fast. Clean cooler fins and verify airflow is not blocked. Confirm oil meets ISO VG46 or ISO VG48 spec. At operating temperature, system pressure should hold 3000 psi (207 bar); if pressure sags under heat, start the overheating diagnosis on page 58.
Manual Section: Hydrostatic System Troubleshooting GuideFrequently Asked Questions
What do the error codes mean on a Gehl 6640E?
This manual lists the Yanmar 4TNV98-ZNMS Engine ECU fault codes, with failure detection conditions, what the engine does when a fault occurs, the action or condition for recovery, the category, and the flash count. A coolant temperature sensor failure, for example, shows 4 flashes, and recovery means correcting the fault. These codes apply to the Gehl 6640E.
What are the replacement specifications for hydraulic filters?
Replace the hydraulic oil filter element once its restriction indicator shows red (page 79). For the correct element, refer to the Gehl or Mustang Parts Manual. After fitting it, hand-tighten until the gasket contacts the filter head, then turn another 3/4 turn to seat it (page 79).
What are the replacement specifications for hydraulic oil?
Run Mobil DTE 15M, Petro-Canada Premium HVI60, or an equivalent oil with anti-rust, anti-foam, and anti-oxidation additives that conforms to ISO VG46 or ISO VG48. The reservoir holds 16 U.S. gallons (61 L). Drain and refill it every 500 hours of operation or annually.
How will I receive this Gehl Mustang 2066 & variants Service Manual?
This is a 145-page searchable PDF, ready to download right away. It works on any device, so pull it up on your phone while you're under the hood. No shipping, no waiting.
Is this Gehl Mustang 2066 & variants Service Manual printable?
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 wiring schematics in this Gehl Mustang 2066 & variants manual?
Complete wiring diagrams are included, covering all electrical circuits, harness routing, and connector pinouts for the Gehl Mustang 2066 & variants.
Document Quality
This document is a scanned PDF, meaning the original pages were physically scanned. An OCR (Optical Character Recognition) layer has been applied, so you can search and copy the full text, though some characters may show slight pixelation from the scanning process. Text quality is consistently clear and easy to read throughout the manual. Diagrams and illustrations are a mix of sharp, vector-like exploded views with readable labels and clear photographs that effectively show component locations. Pages are clean with no noticeable scan artifacts, stains, or skewed content, and there are a few blank "NOTES" pages included as filler.
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