Free - Twin Disc MG-516 Troubleshooting Guide

Twin Disc MG 516 Marine Transmission Parts

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Free - Twin Disc MG-516 Troubleshooting Guide

Twin Disc MG516 Marine Transmission Parts Catalog

Introduction: Proven Reliability for Marine Power

The Twin Disc MG516 marine transmission delivers the dependable power and performance demanded by commercial and recreational marine operators. Known for its smooth power transfer, rugged design, and long service life , the MG516 is a preferred choice for fishing boats, offshore vessels, tugboats, and workboats .

At Diesel Pro Power , we offer a complete selection of MG516 parts , including rebuilt transmissions, overhaul kits, plates, seals, rubber blocks, and more . With fast global shipping, competitive pricing, and expert support, we’re your trusted partner for keeping your MG516 transmission at peak performance.

Rebuilt Twin Disc MG516 Marine Transmissions for Sale

Our rebuilt Twin Disc MG516 transmissions are meticulously reconditioned to OEM specifications , delivering smooth, reliable operation and exceptional durability. Every rebuilt unit undergoes a comprehensive inspection, precise machining, reassembly with premium components, and rigorous testing to ensure it meets the high-performance standards required for marine environments.

Each rebuilt MG516 transmission comes fully tested and equipped with:

Mechanical selector valve assembly (control valve) for precise shifting and reliable gear engagement.
Pilot housing flange , ensuring seamless connection between the engine and transmission.
Oil pump designed to maintain optimal lubrication and cooling, reducing wear on internal components.
Oil level gauge for easy monitoring of transmission fluid levels, supporting regular maintenance.
Output flange to ensure secure power transfer from the transmission to the propeller shaft.

Note: The drive ring is sold separately and can be added as needed.

Choosing the right gear ratio for your vessel is essential for optimizing performance, fuel efficiency, and operational reliability. Our rebuilt MG516 transmissions are available in a range of ratios to meet diverse marine requirements:

Available Ratios:

Twin Disc MG516 Marine Transmission 3.0:1 for Sale
This ratio provides a moderate level of thrust and control , making it ideal for vessels that need consistent performance for diverse tasks. Suitable for mid-sized commercial operations and multipurpose vessels.
Twin Disc MG516 Marine Transmission 3.5:1 for Sale
Delivers increased torque for heavier vessels , including cargo boats and large fishing vessels. The 3.5:1 ratio ensures stable handling and powerful thrust , particularly useful when operating under full load or in variable sea conditions.
Twin Disc MG516 Marine Transmission 4.0:1 for Sale
Offers strong performance and high thrust at lower speeds , making it an excellent choice for trawlers and other heavy-duty vessels . This ratio ensures dependable control and fuel efficiency, even when operating for extended periods.
Twin Disc MG516 Marine Transmission 4.5:1 for Sale
Designed for demanding commercial marine operations , the 4.5:1 ratio delivers exceptional control and high torque , essential for vessels involved in towing, dredging, or other intensive tasks.
Twin Disc MG516 Marine Transmission 5.0:1 for Sale
Provides maximum torque and reliability for the most challenging marine applications, including tugboats, large workboats, and vessels handling significant loads . This ratio ensures steady propulsion and unmatched control under the most demanding conditions.

Every rebuilt MG516 transmission from Diesel Pro Power is ready to install, backed by quality assurance testing, fast global shipping , and the expertise you can trust to keep your vessel running strong.

Essential MG516 Parts for Maintenance and Overhaul

Overhaul Plate Kit – For Twin Disc MG516 Transmission

Our overhaul plate kit includes all the brass friction plates and steel plates required for a complete clutch rebuild. Engineered for precision fit and durability , these plates restore smooth clutch engagement and extend transmission life. Ideal for major overhauls, this kit helps maintain optimal performance under high-load conditions , reducing wear and preventing slippage. Essential for scheduled maintenance or major repairs to keep your MG516 transmission operating efficiently.

Gasket and Seal Kit – For Twin Disc MG516 Transmission

The gasket and seal kit includes everything needed to maintain a leak-free transmission system , with main housing gaskets, O-rings, seal rings, and auxiliary gaskets tailored to the MG516. These components are engineered for resilience against extreme pressures and temperatures , ensuring fluid integrity and consistent system pressure. Regular replacement of gaskets and seals helps prevent contamination and component wear , safeguarding your transmission from unexpected failures.

Plate – For Twin Disc MG516 Transmission

Our high-quality individual brass and steel plates allow for targeted clutch repairs , enabling you to replace worn or damaged components without the need for a full overhaul kit. Precision-manufactured for the MG516, these plates provide reliable clutch engagement, reduced wear, and consistent power transfer , making them ideal for both routine maintenance and emergency repairs.

Rubber Block (Coupling) – For Twin Disc MG516 Transmission

The rubber block , also known as the torsional isolator , connects the transmission output flange to the propeller shaft. It effectively absorbs torsional vibrations , reduces stress on the drivetrain, and compensates for misalignments caused by hull flex or engine movement . Made from marine-grade materials for long-lasting performance, it ensures quieter, smoother operation and extends the life of both the transmission and propeller system.

Seal – For Twin Disc MG516 Transmission

Our high-quality input and output shaft seals , along with dynamic sealing solutions, are designed to maintain internal pressure and prevent fluid leaks . These seals are constructed to withstand the harshest marine conditions , including high-pressure environments, temperature fluctuations, and exposure to contaminants. Regular seal replacement protects critical transmission components, ensuring smooth operation and reducing the risk of costly repairs .

Marine Transmission Specifications & Applications of the Twin Disc MG516

Overview of the Twin Disc MG516 Marine Transmission

The Twin Disc MG516 is a heavy-duty marine transmission engineered for demanding commercial and industrial marine propulsion systems. Designed to accommodate continuous-duty operation at high horsepower and torque levels, the MG516 is a trusted gearbox in offshore trawlers, tugboats, ferries, and supply vessels that require dependable performance in harsh maritime conditions.

This transmission features a heavy-duty cast iron case, oil-cooled hydraulic multi-disc clutch, and pressure lubrication system for extended service life. It’s available in both straight and down-angle configurations, with flexible power take-off (PTO) options and several gear reduction ratios that allow vessel operators to fine-tune propulsion efficiency.

Ideal for use with large displacement diesel engines, the MG516 is built to deliver reliable torque transfer, minimal vibration, and smooth shifting over long duty cycles.

Key Specifications of the Twin Disc MG516

Type: Heavy-duty marine transmission with hydraulic clutch
Horsepower Rating (Approximate):

Continuous Duty: Up to 800 HP @ 1800 RPM
Intermittent Duty: Up to 950 HP @ 2300 RPM

Maximum Input Speed: 2500 RPM
Reduction Ratios Available:

2.00:1
2.50:1
2.95:1
3.47:1
4.00:1

Input Housing: SAE No. 0 or SAE No. 1
Flywheel Compatibility: 18", 14", or custom depending on engine
Clutch Type: Oil-cooled, hydraulically actuated multi-disc clutch
Lubrication System: Full-pressure lubrication with internal oil pump
Cooling System: Oil-to-water heat exchanger standard; oil-to-air optional
Oil Capacity: 16–20 quarts depending on ratio and housing
Dry Weight: Approximately 1,100–1,300 lbs
Mounting Options: Straight or down-angle output; rigid or flexible mounts
Rotation Compatibility: Bi-directional input (supports left- or right-hand engine rotation)
Optional Features:

Hydraulic or mechanical PTO
Trolling valve for low-speed maneuvering
Companion flange or custom shaft output

Common Marine Applications for the MG516

The MG516 is engineered for high-powered propulsion systems and is typically used in commercial vessels that demand long operational life, high load capacity, and minimal downtime. Typical applications include:

Offshore Trawlers: Designed to handle heavy fishing gear loads and continuous-duty propulsion at sea.
Tugboats & Pushboats: Supports powerful diesel engines in towing, docking, and maneuvering operations.
Supply & Utility Vessels: Proven in vessels that deliver cargo, crew, and equipment to offshore installations.
Dredging Vessels: Effective in power-hungry dredging operations that require durable and stable gear engagement.
Passenger and Vehicle Ferries: Common in mid-size ferry systems requiring consistent, high-torque performance.

Most Common Engine Models Paired with the Twin Disc MG516

The MG516 is typically paired with high-output diesel engines in the 600–950 horsepower range. It integrates easily with leading engine brands and is frequently found in fleets using the following marine diesel platforms:

Cummins Marine Engines

Cummins KTA19-M3 / KTA19-M4
Cummins KTA38-M1 / M2
These high-horsepower inline and V12 Cummins engines are widely used in commercial applications requiring reliable continuous-duty propulsion.

Detroit Diesel Marine Engines

Detroit Diesel 12V71TI
Detroit Diesel 16V71
Often used in pushboats and dredges, these engines are commonly paired with MG516 transmissions in older, high-horsepower vessels.

Caterpillar Marine Engines

Caterpillar 3408C / 3408E
Caterpillar 3412
Caterpillar C18
These engines pair well with MG516 transmissions in commercial fishing, ferry, and workboat fleets.

MTU Marine Engines

MTU Series 183 and 396 (Select Ratings)
In military and offshore supply applications, the MG516 provides a rugged match for MTU platforms requiring reliable clutch performance and thermal stability.

Scania & MAN Marine Engines

Larger inline-6 and V8 models in medium-duty configurations, typically paired in retrofit projects where a compact, down-angle gearbox is required.

Diesel Pro Power recommends torque curve verification, alignment checks, and proper oil cooling integration when pairing the MG516 with high-output diesel engines.

Benefits of the Twin Disc MG516 Transmission

Heavy-Duty Clutch System: Oil-cooled multi-disc clutch allows for smooth, reliable engagement under high load.
Long Life Under Load: Pressure lubrication and robust geartrain extend service life under continuous-duty applications.
Flexible Mounting and Output Options: Available in straight or down-angle for multiple vessel layouts.
Supports PTO and Trolling Valve Integration: Easily supports winches, pumps, or auxiliary systems from main engine power.
Compatible with Industry-Standard Engines: Works with SAE No. 0 or No. 1 housings across major diesel platforms.

Ideal Use Cases for the MG516

Vessel Type	MG516 Suitability	Comments
Offshore Trawlers	Excellent	Built for continuous duty with high propeller load
Tugboats and Pushboats	Excellent	Handles frequent gear changes and full-load torque
Ferries and Transport Vessels	Excellent	Supports long shifts and high-reliability needs
Dredging and Survey Vessels	Excellent	High oil capacity supports long-duty dredging ops
Fast Patrol Craft	Not Recommended	Too heavy and geared for low-RPM torque delivery
Recreational Boats	Not Recommended	Oversized for non-commercial, light-duty applications

Additional Resources

Practical Guide to Servicing the Twin Disc MG516 Marine Gear

Introduction

Overview of the Twin Disc MG516 and MG5161
Why regular maintenance matters for marine transmissions
Who this guide is for: fleet operators, commercial captains, independent marine mechanics
Disclaimer: Refer to the OEM service manual for exact torque specifications and detailed technical procedures

Technical Overview of the MG516 Marine Gear

Key Features of the MG516

Heavy-duty marine transmission designed for commercial use
Smooth hydraulic shifting and durable reverse gear system

General Specifications

Model: MG-516 and MG-5161
Gear ratios
Oil capacity and type
Dry weight and dimensions
Recommended operating pressures

Safety Precautions and Required Tools For The Twin Disc MG516 Marine Gear

Personal Protective Equipment (PPE)

Essential gear for safe maintenance work

Lockout/Tagout Procedures

Ensuring system is de-energized before beginning service

Recommended Tools

List of essential mechanical and diagnostic tools

Routine Maintenance Tasks For The Twin Disc MG516 Marine Gear

Oil Change Intervals

Frequency and best practices

Filter Element Replacement

Locations and procedures

Visual Inspection Checklist

Early signs of wear or failure

Draining and Refilling the Transmission Oil

Draining Procedures

How to safely remove used oil

Refilling Procedures

Steps to properly refill and confirm correct levels

Hydraulic System Servicing

Checking Operating Pressure

How to check and what PSI range is acceptable

Replacing Hydraulic Seals

Where to inspect and how to replace common failure points

Clutch and Gear Inspection For Twin Disc MG516 Marine Gear

Clutch Pack Inspection

Wear indicators and disassembly notes

Gear Train and Tooth Wear

Backlash measurement and gear condition inspection

Output Shaft and Rear Housing Maintenance For Twin Disc MG516 Marine Gear

Bearing and Seal Inspection

What to look for and when to replace

Shaft Alignment and Runout

How to check for misalignment and correct it

Cooler and Oil Circulation System For Twin Disc MG516 Marine Gear

Heat Exchanger Inspection

Inspection and flushing procedures

Oil Flow Testing

How to confirm proper cooling and flow rate

Control Valve Maintenance For Twin Disc MG516 Marine Gear

Solenoid and Valve Cleaning

Steps for removing and cleaning the valve assembly

Testing Shifting Operation

Manual and electronic troubleshooting procedures

Reassembly Tips and Best Practices For Twin Disc MG516 Marine Gear

Torque Specifications

Use of torque wrenches and common values

Use of Gasket Sealant and RTV

Best practices for leak prevention

Pre-Startup Checks

Final inspection and pre-run checklist

Recommended Spare Parts and Kits For Twin Disc MG516 Marine Gear

Rebuild Kits

What’s included and where to get them

Commonly Replaced Parts

Filters, gaskets, clutches, and seals

When to Replace vs Rebuild

Cost analysis and downtime consideration

Troubleshooting Guide For Twin Disc MG516 Marine Gear

Common Symptoms and Causes

No drive, slipping, or delayed engagement

Diagnostic Tips

Interpreting pressure readings and performance issues

When to Call a Specialist

Scenarios that require professional intervention

Storage, Preservation & Long-Term Maintenance For Twin Disc MG516 Marine Gear

Preparing for Long-Term Lay-Up

Fluid recommendations and corrosion prevention

Periodic Maintenance in Storage

Rotating the shaft, checking fluid, and inspections

50 Frequently Asked Questions About The Twin Disc MG516 Marine Gear

Why Choose Diesel Pro Power for MG516 Parts?

Extensive inventory of MG516 parts , including rebuilt transmissions, overhaul kits, plates, rubber blocks, seals, and more.
Fast shipping worldwide, with most orders processed within 24 hours.
Competitive pricing on OEM-quality parts for reliable performance.
Expert technical support to assist with part selection and installation.

Frequently Asked Questions (FAQs) about the Twin Disc MG516

1. What types of vessels use the Twin Disc MG516?

The MG516 is ideal for fishing boats, tugboats, offshore supply vessels, workboats, and recreational yachts .

2. What parts should I keep on hand for maintenance?

Essential parts include the overhaul plate kit, gasket and seal kit, plates, coupling, and seals .

3. What’s included in the overhaul plate kit?

The kit includes all brass friction plates and steel plates for a complete clutch rebuild.

4. How often should I change the oil and filter in the MG516?

Change the oil and filter every 500 hours of operation or annually , whichever comes first.

5. What type of oil is recommended for the MG516?

Use SAE 30W engine oil for temperatures between 150°F and 185°F, and SAE 40W for 185°F to 210°F.

6. How do I know when to replace the rubber block?

Replace it if you notice increased vibrations, noise, or visible wear and cracking during inspections.

7. Are Diesel Pro’s aftermarket parts reliable?

Yes! They’re designed to meet or exceed OEM standards , providing long-lasting performance.

8. How fast can I get MG516 parts from Diesel Pro Power?

Orders are typically processed within 24 hours , with global shipping options available.

9. What signs indicate my MG516 needs maintenance or overhaul?

Look for slipping gears, fluid leaks, unusual noises, overheating, or reduced performance .

10. Can Diesel Pro Power help me select the right parts?

Absolutely! Our team offers expert support and guidance to ensure you choose the correct parts for your MG516 transmission.

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