This is the factory service manual for the Mustang AL 406 and AL506 articulated loaders, covering machines built with the Yanmar 4TNV88-BKGWL diesel engine across the AL 400 and AL 500 serial series. Published as part number 50940008, it runs 220 pages of repair-level detail.Inside are full procedures for engine removal and installation, the hydrostatic drive and work hydraulics, front and rear axles, the cooling system, the machine and drive controllers with their error codes, and complete electrical schematics. Maintenance schedules, fluid capacities, and torque specifications are all included.With this PDF you can diagnose a weak or erratic hydraulic circuit, pressure-test the drive and work systems, replace seals and filters to spec, and work through the diagnostic flow charts instead of guessing. It is the same information a dealer technician uses to service these loaders.
What's Inside This Mustang AL 406, AL506 Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction | 7-8 | Safety Symbol, Signal Words, Contents and Use of this Manual, Machine Orientation, Service Parts |
| Safety | 9-16 | - |
| Maintenance | 23-54 | Engine Air Cleaner, Engine Maintenance, Engine Oil, Maintenance Log, Maintenance Schedule, Check, Clean and Inspect, Functional Check |
| Operation | 55-66 | Operation Safety, Controls and Switches, Instrument Panel and Indicators |
| Chassis | 67-84 | Tilting the Platform, Lowering the Platform, Repairing or Replacing Platform Switch (Series: 41249 and Before, 51241 and Before), Hood Removal, Hood Installation |
| Engine | 85-94 | Engine Removal, Engine Installation, Drive Coupling Removal, Starter Removal |
| Cooling System | 95-100 | Radiator/Oil Cooler Removal, Radiator/Oil Cooler Installation |
| Axles | 101-108 | Front Axle Removal, Front Axle Installation, Rear Axle Removal, Rear Axle Installation |
| Hydraulics | 109-172 | Work Hydraulics Troubleshooting, Hydrostatic Drive System, Hydraulics Troubleshooting Diagnostic Flow Charts, Drive System Pressure Tests, Work System Pressure Tests |
| Machine/Drive Controllers | 173-188 | Machine and Drive Controllers, Machine Controller (Led/Indicator Assignments, Logic), Drive Controller (Error Codes) |
| Electrical System | 189-202 | Battery Removal, Battery Installation, Al 400 Series Complete Electrical Schematic, Al 400 Series Steering Column Electrical Schematic, Al 400 Series Chassis Electrical Schematic |
| Troubleshooting | 203-210 | Indicator Lamps / Seals and Hoses, Hydraulic System, Hydrostatic Drive System, Electrical |
| Torque Specifications | 215-219 | Hydraulic Fittings with Various Seals, With Coarse-Pitch Thread, With Fine-Pitch Thread |
| Back Cover | 220 | Mustang Manufacturing Co., Inc., P.O. Box 179, West Bend, 53095-0179 Usa, Www.Mustangmfg.Com |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Hydraulic fluid and return filter replacement interval | 500 Hours (or annually) | p. 25 |
| Hydraulic oil filter installation (gasket tightening) | 3/4 rotation past point where gasket contacts filter head | p. 35 |
| Hydraulic hose replacement action (damaged/leaking) | Repair/replace as required | p. 109 |
| Hydraulic fitting torque (M10X1.0, Sealing washer) | 7 lb-ft (9 Nm) | p. 215 |
| Hydraulic cylinder seals replacement action | Remove and discard, then install new seals | p. 149 |
| Teflon piston seals installation temperature | 130°-140° F (54°-60° C) | p. 147 |
| Fuel filter replacement interval | 500 Hours (or annually) | p. 25 |
| Fuel filter installation (gasket tightening) | 3/4 turn past point where gasket contacts filter head | p. 31 |
| Starter power rating | 12V - 2.3 kW | p. 21 |
| Starter mounting bolts torque | 64 lb-ft (87 N•m) | p. 94 |
| Gear/Work Hydraulic Pump mounting bolts torque | 33 lb-ft (45 N•m) | p. 155 |
| Piston/Drive Hydraulic Pump mounting bolts torque | 92 lb-ft (125 N•m) | p. 158 |
Mustang AL 406, AL506 Common Problems This Manual Covers
Weak or erratic hydraulic functions
Lift, tilt, or drive functions that go weak, jerky, or quit under load usually trace to low or contaminated fluid, air in the system, clogged filters, or pump wear. The Hydraulics section walks through diagnostic flow charts and work and drive system pressure tests to isolate the fault.
Manual Section: Hydraulics p. 109Loader will not start or dies
Cranking faults, a bad starter, or a failed drive coupling leave the machine dead or stalling. The Engine section covers starter removal and installation and drive coupling service, with the starter mounting torque spelled out.
Manual Section: Engine p. 85Sluggish or unresponsive articulation
An articulated loader steers on hydraulics, so slow or jerky articulation points to a restricted circuit, low fluid, or a steering valve fault. The Hydraulics section provides the pressure tests and troubleshooting charts to trace it.
Manual Section: Hydraulics p. 109Drive power drops or error codes appear
When travel performance falls off or the machine flags a fault, the drive controller error codes point to the cause. The Machine/Drive Controllers section maps the LED and indicator assignments and lists the drive controller error codes.
Manual Section: Machine/Drive Controllers p. 173Overheating or coolant loss
Restricted airflow, a damaged radiator or oil cooler, or leaking hoses show up as overheating and repeated fluid loss. The Cooling System section covers radiator and oil cooler removal and installation.
Manual Section: Cooling System p. 95Missed service and clogged filters
Skipped intervals let hydraulic and fuel filters clog and wear parts go unchecked. The Maintenance section gives the full schedule, with hydraulic and fuel filters due at 500 hours or annually.
Manual Section: Maintenance p. 23Frequently Asked Questions
Which machines does this manual cover?
It covers the Mustang AL 406 and AL506 articulated loaders across the AL 400 and AL 500 serial series, all built with the Yanmar 4TNV88-BKGWL diesel engine. Part number 50940008.
Does it list hydraulic fitting torque values?
Yes. The Torque Specifications section gives hydraulic fitting torque, for example M10X1.0 fittings from 7 lb-ft (9 Nm) with a sealing washer up to 13 lb-ft (18 Nm) with an elastic seal. p. 215
Can I troubleshoot the hydrostatic drive with it?
Yes. The Hydraulics section includes diagnostic flow charts plus drive system and work system pressure tests so you can pinpoint hydrostatic and work hydraulic faults. p. 109
How often should the filters be changed?
The Maintenance section lists the schedule; hydraulic and fuel filters are due at 500 hours or annually, along with inspection of hinge pins, bushings, and pivot bolts. p. 23
What format is this Mustang AL 406, AL506 manual in?
Instant PDF download. You get the full 220-page searchable Service Manual immediately after payment. Open it on your laptop, tablet, or phone right in the shop.
Can I print specific sections of this Mustang AL 406, AL506 Service Manual?
Yes. The PDF has no DRM restrictions — print any page or section you need for your shop. Works with any standard printer.
Does this Mustang AL 406, AL506 manual include hydraulic schematics?
Yes — complete hydraulic schematics with flow diagrams, valve configurations, and pressure specifications are included.
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