All 343 pages of this Mustang MTL320 Service Manual (OEM #917343) zero in on one machine: your MTL320 Track Loader, from hydraulic teardown to full electrical diagnosis. Inside, you get complete electrical wiring and wire harness diagrams across high-detail schematics, plus hydraulic system coverage that walks through the HST pump, gear pump, control valve, sub valve, pilot valve, proportional control solenoid valve, cylinders, and travel motor — every assembly with exploded views. Troubleshooting covers travel faults, lift arm issues, bucket response, auxiliary hydraulics, and overall machine diagnosis. Top off the engine oil pan to exactly 10.2 L and the hydraulic tank to 49 L; if the machine won't respond, check SUB valve pilot pressure against the factory spec of 3.2 MPa (right) and 2.1 MPa (left). Your machine is down. Pull up this PDF on your tablet, search any spec by keyword, and start wrenching.
What's Inside This Mustang MTL320 Manual
| System | Pages | Key Topics |
|---|---|---|
| Safety | 3-12 | - |
| Service Data | 13-70 | Electrical Wiring Diagram, Wire Harness Diagram |
| Function | 71-120 | Air Conditioner System |
| HST Pump | 150-200 | - |
| Gear Pump | 201-205 | - |
| Gear Pump (High Flow) | 206-210 | - |
| Control Valve | 211-216 | - |
| Sub Valve | 217-225 | Control Valve (High Flow) |
| Pilot Valve | 226-232 | - |
| Cylinders | 233-248 | Proportional Control Solenoid Valve |
| Travel Motor | 249-270 | - |
| Troubleshooting | 271-343 | Overall Machine, Traveling, Lift Arm, Bucket, Auxiliary Hydraulics, HST Pump |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| General tightening points for M6 x 1.0 (Coarse) bolt | 9.8 ±0.5 N·m | p. 30 |
| SUB valve pilot pressure (right) | 3.2 MPa | p. 275 |
| SUB valve pilot pressure (left) | 2.1 MPa | p. 275 |
| Engine oil pan capacity | 10.2 L | p. 18 |
| Hydraulic oil tank capacity | 49 L | p. 18 |
| Engine cooling system capacity | 16.5 L | p. 18 |
| Fuel tank capacity | 90 L | p. 19 |
| Rated engine speed | 2500 min-1 | p. 16 |
| Maximum engine torque | 272.5 to 296.7 N·m | p. 16 |
| Hydraulic pump set pressure | 34.5 MPa | p. 16 |
| Control valve set pressure | 3.3 MPa | p. 17 |
| General tightening torque (M10 x 1.5, Steel) | 47.1 ±2.4 N·m | p. 30 |
Mustang MTL320 Common Problems This Manual Covers
Mustang MTL320 loader and attachments won't operate despite engine running, no hydraulic response
Check the relay panel for failed control-circuit relays. This is the most common cause of total operational loss on this machine. Inspect each relay for continuity and swap suspect units with known-good spares. Verify sub valve pilot pressure reaches 3.2 MPa (right) and 2.1 MPa (left) on page 275 before condemning the hydraulic circuit.
Manual Section: Overall Machine TroubleshootingEngine starts and runs normally but lift arm won't raise under load
Inspect hydraulic oil level. The tank holds 49 L and low fluid starves the lift circuit. Verify pump outlet pressure against the 34.5 MPa set pressure; if low, the gear pump is suspect. Pull the arm cylinder and check for internal seal bypass. Compare control valve set pressure against the 3.3 MPa spec on page 17.
Manual Section: Lift Arm System TroubleshootingMachine tracks veer or pull to one side during travel, won't go straight
Check crawler tension on both tracks. Spec is 25 to 50 mm sag at the midpoint, per page 20; adjust the tensioner idler if either side is out of range. Verify HST pump output is balanced side-to-side. Uneven pump displacement causes persistent pulling. If hydraulic balance checks out, inspect the travel motor per the Travel Motor Troubleshooting section.
Manual Section: Traveling System TroubleshootingBucket won't curl or dump, cylinder moves slowly or not at all
Verify hydraulic oil level is at the full mark (49 L total tank capacity). Measure control valve set pressure against 3.3 MPa on page 17; a pressure drop here causes slow bucket response. Remove and bench-test the bucket cylinder seals for internal bypass. Check the proportional control solenoid valve if auxiliary flow is also affected.
Manual Section: Bucket System TroubleshootingAuxiliary hydraulics port has no flow, attachment spins slowly or not at all p. 275
Test proportional control solenoid valve response with a pressure gauge at the auxiliary port. Compare against the control valve set pressure of 3.3 MPa on page 17. Inspect the sub valve pilot pressure: right side should read 3.2 MPa, left side 2.1 MPa, per page 275. Clean or replace the proportional control solenoid if pressure is absent.
Manual Section: Auxiliary Hydraulics TroubleshootingFrequently Asked Questions
What are the torque specs for Mustang MTL320 track adjuster components?
The manual specifies a torque of 59 N·m for the check valve, which is part of the track adjuster system. This value is mentioned in the procedure for loosening the tension of the crawler belt.
How do I bleed the hydraulic system on a Mustang MTL320 after maintenance?
To bleed the hydraulic system after maintenance, first fill the servo control chambers of the HST pump with hydraulic oil and install the pump. Then, fill the pilot hoses with oil, remove plugs from pilot ports (X1, X11, X2, X12), and connect hoses. Finally, fill the pump with oil through the plug hole (1) and pressure detection ports (M5, M15), start the engine at idling speed for five minutes, and slowly operate the pilot valve to bleed air from the main and pilot circuits. For cylinders, start the engine at low idle for 10 minutes, then extend and retract each cylinder 4 or 5 times without reaching stroke end, repeat at high speed, and then return to low idle.
How to find torque specs for Mustang MTL320?
The manual provides detailed tightening torque specifications for various components. For hydraulic hoses, refer to the tables on page 28 for Union nut (G) and Taper thread (R) values, such as 9.8 N·m for 1/8 inch Union nut. For bite-type pipe fittings for steel pipe, values like 34.3 N·m for 8 mm outer diameter are listed on page 28. General tightening points for bolts and nuts (JIS strength category 10.9) are provided on page 30, with values like 9.8 N·m for M6 x 1.0 coarse thread.
Is this Mustang MTL320 Service Manual a digital download?
A 343-page Service Manual in searchable PDF format, available the moment you complete checkout. View on computer, tablet, or phone — no shipping wait.
Is this Mustang MTL320 Service Manual printable?
Yes. The PDF has no DRM restrictions — print any page or section you need for your shop. Works with any standard printer.
Are electrical wiring diagrams included in this Mustang MTL320 Service Manual?
Yes. You'll find full electrical schematics with wire routing diagrams, connector identification, and circuit descriptions.
Document Quality
This document is a scanned PDF, not a native digital file, but an OCR layer has been applied, allowing you to search and copy the text. The text quality is generally crisp and clear throughout the manual, making it easy to read. Diagrams and illustrations are raster images, not vector, which means some fine details and small text in complex wiring diagrams (e.g., pages 33-69) appear blurry and are difficult to decipher, though most other diagrams are adequately clear. Pages are clean with no noticeable scan artifacts, stains, or skewed content, and there are no notable blank or filler pages.
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