Removing a Cummins 6BT and Twin Disc MG502 from an Iconic 31′ Bertram

In the short video shared with us, our customer Dion from Imperial Diesel Service—along with his customer—is seen working through the tight confines of an iconic 31′ Bertram to remove a Cummins 6BT engine paired with a Twin Disc MG502 marine transmission. Anyone familiar with the Bertram 31 knows the challenge: legendary performance, but extremely limited engine room space. Pulling a powertrain from one of these classic hulls requires skill, patience, and the kind of marine diesel experience that Dion has built his reputation on.

The 31′ Bertram is one of the most celebrated sportfishing boats ever produced—often restored, repowered, and upgraded by enthusiasts who want modern reliability in a vintage package. Many of these boats were repowered with Cummins 6BT engines, known for their durability, simplicity, and strong performance. Likewise, the Twin Disc MG502 transmission remains a popular choice for this horsepower range, offering smooth shifting, long service life, and excellent parts support.

This video of our customer Dion  captures the reality of real-world marine service work: tight engine rooms, heavy components, specialized lifting equipment, and the constant need for absolute precision. Removing a Cummins 6BT paired with a Twin Disc MG502 transmission from a Bertram 31 is no small job. It requires careful planning, experienced hands, and an understanding of how every component interacts in a confined marine environment. One wrong move can damage mounts, wiring, or critical drivetrain components, turning a routine service operation into an expensive setback.

This type of work highlights just how demanding marine service can be—and why shortcuts are never an option. When an engine and transmission are already out of the boat, there’s no room for questionable parts or guesswork during reinstallation. It’s a clear reminder of how important high-quality components, proper fitment, and knowledgeable technical support are when it’s time for a rebuild, overhaul, or repower. Choosing reliable parts and working with a supplier who understands marine drivetrain systems helps ensure that all the effort invested in removal and installation results in long-term performance, reliability, and confidence once the boat is back on the water.

Why Diesel Pro Power Is the Best Source for Cummins 6BT Parts

The Cummins 6BT has become one of the most widely used diesel engines in the marine world, not only for repowers but also for commercial vessels, workboats, and recreational fishing boats. Operators rely on the 6BT because it is simple, mechanical, and capable of running thousands of hours with proper parts and maintenance.

Diesel Pro Power is a leading supplier of high-quality aftermarket parts and components for the Cummins 6BT, supporting both marine and industrial configurations. Customers choose Diesel Pro Power because:

Extensive Inventory

From cylinder heads, pistons, liners, and camshafts to water pumps, fuel system components, sensors, and gaskets—Diesel Pro Power stocks a wide range of parts ready for fast shipment.

Strict Quality Standards

Parts supplied by Diesel Pro Power meet or exceed OEM specifications. This ensures long service life, reliable operation, and proper fitment for both standard and marine 6BT applications.

Fast Worldwide Shipping

For vessels on tight schedules, downtime can be costly. Diesel Pro Power ships quickly to 180 countries, supporting operators wherever their vessels are located.

Knowledgeable Support Team

Whether it’s helping identify the correct marine cooling configuration, selecting the right gasket set, or guiding rebuild planning, Diesel Pro Power’s team provides expert assistance grounded in decades of diesel engine experience.

Your Best Source for Rebuilt Twin Disc MG502 Transmissions

The Twin Disc MG502 is one of the most trusted marine transmissions in the 200–300 horsepower range. It is found in commercial vessels, charter boats, and countless 31 Bertram repowers. Built for durability and smooth modulation, the MG502 is the perfect match for engines like the Cummins 6BT.

Diesel Pro Power offers:

Professionally Rebuilt MG502 Transmissions

Each rebuilt MG502 is handled by technicians who understand Twin Disc products inside and out. Internal components are inspected, machined, replaced, and tested to ensure the transmission performs like new.

Parts to Repair Your Own MG502

For operators and mechanics who prefer to overhaul the transmission themselves, Diesel Pro Power supplies:

• Clutch packs

• Bearings

• Seals and gasket kits

• Oil pump components

• Plates and discs

• External hardware and mounts

With multiple MG502 parts in stock, operators can avoid long OEM lead times and get back on the water quickly.

Technical Support

Diesel Pro Power helps customers identify the correct MG502 ratio, configuration, and parts required for their specific installation—crucial for older boats like the Bertram 31 where custom setups are common.

Why Buy Twin Disc MG502 Parts from Diesel Pro Power

1. Correct Parts for the MG502 Transmission
Twin Disc MG502 marine transmissions require precise, model-specific components to operate correctly and reliably. Diesel Pro Power supplies MG502 parts that are carefully matched for proper fitment, spline counts, pressure ratings, and marine-duty requirements. This attention to detail significantly reduces the risk of ordering errors, installation issues, or compatibility problems that can lead to premature failure or costly downtime.

2. Premium Aftermarket Components Built for Marine Use
Diesel Pro Power offers premium aftermarket Twin Disc MG502 parts engineered to handle the continuous load, heat, and torque common in marine propulsion systems. These components are selected for durability and consistent performance in harsh saltwater environments, where reliability is critical and failure is not an option.

3. Reduced Downtime & Faster Repairs
When a vessel is out of service, time equals money. Sourcing the right MG502 parts quickly is essential to keeping projects on schedule. Diesel Pro Power helps streamline the repair process by stocking commonly replaced wear items and service components, allowing mechanics and operators to complete repairs efficiently and get back underway sooner.

4. Backed by Hands-On Marine Drivetrain Knowledge
Diesel Pro Power isn’t just a parts distributor—we work daily with marine engines and transmissions. That real-world experience translates into knowledgeable technical support, fitment verification, and practical guidance when servicing Twin Disc MG502 units, helping avoid costly mistakes during installation.

5. Ideal for Commercial & Recreational Applications
Whether you’re maintaining a commercial workboat, charter vessel, or private yacht, Diesel Pro Power’s Twin Disc MG502 parts are suited for a wide range of marine applications. These components support long service intervals, smooth shifting, and consistent power transfer from engine to propeller.

6. Long-Term Value & Reliability
Investing in quality MG502 parts helps prevent premature failures, clutch issues, and repeat repairs. Diesel Pro Power’s focus on dependable components helps protect your transmission investment, extend drivetrain life, and deliver reliable performance season after season.

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