Hydraulic Control System Overview and Testing For Allison M & MH Marine Transmissions

Overview of the Hydraulic Control System

Valve Body Components and Layout

Selector Valve Assembly:

Internal Passages:

Pressure Regulation Port:

Auxiliary Check Valves and Dump Valves:

Pressure Testing Procedures

Required Tools:

Test Setup:

Interpreting Results:

Solenoid Function and Replacement

Function of Solenoids:

Symptoms of Faulty Solenoids:

Replacement Procedure:

Internal Passage Cleaning

When to Clean Passages:

Cleaning Steps:

Important Tips:

Testing With Hydraulic Gauges

Recommended Gauges:

What to Monitor:

Testing Intervals:

Data Logging:

System Upgrades and Preventative Improvements

Available Enhancements:

Best Practices:

Common Hydraulic Failures and Troubleshooting

Issue: Delayed engagement in forward or reverse

Issue: Overheating

Issue: Fluctuating oil pressure

Issue: No clutch engagement

Issue: Oil leaks

Conclusion

Oil Pump Service For Allison M & MH Marine Transmissions

Identifying Symptoms of Oil Pump Failure

Common Symptoms of Oil Pump Issues:

Accessing and Removing the Oil Pump

Step-by-Step Removal:

Rotor and Housing Wear Inspection

Key Inspection Points:

Visual Inspection Tips:

Replacing or Rebuilding Components

Rebuild Steps:

Replace with New Pump:

Reinstallation and Priming

Reinstallation Procedure:

Priming the Oil System:

Final Notes on Oil Pump Service

Parts Available From Diesel Pro Power

Benefits:

FAQ

Clutch Inspection and Replacement Procedures For Allison M & MH Marine Transmissions

Accessing the Clutch Pack

Wear Patterns and Friction Plate Scoring

Spring, Disc, and Piston Checks

Return Springs

Discs

Pistons

Clearance Measurements

Reassembly with Proper Preload

Key Reassembly Points:

Post-Installation Checks

Summary of Tools Required

Final Thoughts

For More Information

Inspecting and Replacing Bearings and Gears For Allison M & MH Marine Transmissions

Identifying Signs of Wear For Allison M & MH Marine Transmissions

Common Indicators of Gear and Bearing Wear

Disassembly Prep and Safety For Allison M & MH Marine Transmissions

Tools and Materials Needed

Safety Best Practices

Work Area Setup

Gear Inspection Tolerances For Allison M & MH Marine Transmissions

Key Gear Types in Allison M & MH Transmissions

Inspection Checklist

Visual Examination

Backlash Measurement

Runout Testing

Tooth Pattern Contact

Hardness Testing (optional)

Bearing Removal and Press-Fit Install For Allison M & MH Marine Transmissions

Bearing Removal Procedures

Bearing Installation Procedures

Rechecking Alignment and Backlash For Allison M & MH Marine Transmissions

Shaft and Gear Alignment Checks

Torque Final Hardware

Post-Rebuild Pressure Test

Test Run with Load

Final Notes On Inspecting and Replacing Bearings and Gears For Allison M & MH Marine Transmissions

Daily, Weekly, and Seasonal Checks For Allison M & MH Marine Transmissions

Daily Checks (Pre-Operation)

Weekly Checks

Seasonal or Monthly Checks (Depending on Usage)

Oil and Filter Change Intervals For Allison M & MH Marine Transmissions

Recommended Oil Change Intervals

Filter Replacement Best Practices

Temperature and Pressure Monitoring For Allison M & MH Marine Transmissions

Operating Temperature Ranges

Tip:

Monitoring Options

Normal Hydraulic Pressure Ranges (MH Series)

Linkage and Cable Adjustment For Allison M & MH Marine Transmissions

When to Adjust Linkage or Cables

Mechanical Linkage (Rod System)

Cable Control Systems

Fluid Sampling For Wear Indicators For Allison M & MH Marine Transmissions

What to Look For

Laboratory Fluid Analysis

Final Thoughts On Scheduled Maintenance For Allison M & MH Marine Transmissions

Initial Startup Procedure For Allison M & MH Marine Transmissions

Priming Lubrication Systems For Allison M & MH Marine Transmissions

Manual Priming Methods

Priming Tips

Fluid Type and Fill Instructions For Allison M & MH Marine Transmissions

Approved Fluid Types

Fluid Capacity Guidelines

Fill Procedure

Manual Engagement and Rotation For Allison M & MH Marine Transmissions

Engaging Forward and Reverse

When Manual Rotation Is Difficult

Air Testing and Pressure Checks For Allison M & MH Marine Transmissions

Air Testing the Clutch Packs

Static Hydraulic Pressure Test

First-Run Operating Parameters For Allison M & MH Marine Transmissions

Step-by-Step First Start Procedure

Monitoring for Issues

Fluid Recheck and Top-Off

Short Sea Trial (Optional)

Final Considerations For Allison M & MH Marine Transmissions