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When a Twin Disc MG5114A marine transmission is in service, it’s engineered to withstand high torque, salt air, and thousands of hours of operation. But what about when it’s not installed? Whether you’re preparing for off-season layup, long-term fleet storage, or crating the transmission for shipment, how you protect and maintain the unit while idle is just as important as how you run it in the water.
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Poor storage can lead to:
- Internal corrosion
- Oil contamination
- Seized components
- Costly rebuilds before reinstallation
This comprehensive guide provides the best practices for proper storage, safe shipping, and off-season maintenance—so your MG5114A is ready to work when you are.
Proper Storage Practices
Why Proper Storage Matters
Marine transmissions like the MG5114A contain high-precision gear surfaces, tight-tolerance clutch assemblies, and hydraulic passageways. If exposed to moisture, dust, insects, or temperature extremes, these internal systems can quickly deteriorate—even if the transmission hasn’t run a single hour.
Long-term storage without protection can result in:
- Rust on gear teeth and shafts
- Water ingress through open ports
- Contaminated hydraulic passages
- Hardening or cracking of oil seals
- Milky or acidic oil due to condensation
Implementing a proper storage protocol ensures the unit stays preserved, functional, and ready for smooth reinstallation.
Sealing All Open Ports
Once the transmission is removed from the vessel or pulled for bench storage:
- Drain all fluids—including oil from the main housing and cooler lines.
- Wipe all surfaces clean using lint-free rags and degreaser.
- Identify and cap or plug the following:
- Input and output shaft bores
- Dipstick and fill port
- Cooler ports (inlet and outlet)
- Vent or breather openings
- Drain plugs and pressure test ports
- Selector shaft access (if applicable)
Use rubber caps, threaded plugs, or plastic shrink wrap combined with zip ties or band clamps to keep out air, moisture, and insects.
Important: Avoid using tape over ports—it can dry out, crack, and leave adhesive residue inside hydraulic passageways.
Using Desiccant Packs or Anti-Corrosion Spray
Desiccant Packs
- Place silica gel or moisture-absorbing desiccant packs inside the bell housing or inspection covers.
- Change packs every 6 months if stored in humid environments.
- Ideal for indoor, temperature-controlled storage.
Vapor Corrosion Inhibitor (VCI) Sprays
- Use VCI spray on gear surfaces, clutch packs, and exposed shafts.
- Leave a thin protective film that prevents oxidation and rust formation.
- Can be cleaned off with solvent or oil rinse before reactivation.
Fogging Oil
For longer-term storage (12 months+), apply marine fogging oil:
- Spray a light mist into oil ports and clutch cavities.
- Rotate the output shaft slowly to distribute evenly.
- Helps prevent clutch plate adhesion and internal pitting.
Pro Tip: Always record the preservation steps used on a label attached to the gear housing or crate. This lets the next tech know what was applied.
Environmental Considerations
Store the MG5114A in a dry, climate-controlled environment. Avoid:
- Direct sunlight (UV exposure can degrade gaskets and seals)
- Concrete floors (which emit moisture and promote rust)
- Storage near chemical drums or corrosive vapors
- Locations with rodent activity or high dust levels
Place the gear on a wooden pallet or vibration-absorbing stand, at least 4 inches off the ground, and cover with a breathable tarp or storage hood (not plastic sheeting, which traps moisture).
Shipping Considerations
The MG5114A is a heavy-duty unit, typically weighing between 850–950 lbs, depending on ratio and configuration. When shipping to a customer, shipyard, or workshop, handling must be done with extreme care to prevent:
- Housing cracks
- Shaft or flange bending
- Port damage
- Paint or identification tag loss
- Fluid leaks or contamination during transit
Crating and Lifting Points
Lifting Safely
- Always use engine hoists, gantry cranes, or forklifts with rated capacity.
- Attach lifting hooks to dedicated lifting eyes on the transmission housing.
- If lifting with straps, use rated lifting slings and a spreader bar to distribute load.
- Never lift from oil cooler ports, solenoids, or output flanges.
Crating Guidelines
- Build a crate or skid that:
- Supports the entire gear base and center of gravity
- Allows access to lifting points
- Prevents tipping or shifting in transport
- Use shock-absorbing blocks under mount feet or output shaft to reduce vibrations.
- Include blocking or bracing to keep the unit centered in the crate.
Label the crate with:
- Weight
- Center of Gravity
- Lifting Instructions
- Storage Orientation (“This Side Up”)
- Do Not Stack
Use corrosion-proof hardware, especially for international shipments where ocean freight introduces salt air exposure.
Labeling Hydraulic Line Locations
During shipping or teardown, many failures later occur due to misrouting or incorrect reconnection of hydraulic lines.
Prevent mistakes with proactive labeling:
- Use color-coded zip ties or labels on each hydraulic port.
- Write “COOLER RETURN,” “FORWARD CLUTCH,” “REVERSE CLUTCH,” and “SUCTION INLET” where appropriate.
- Take photos of the routing prior to disconnection.
- Include a hard copy of the schematic or label diagram in the crate.
Diesel Pro Power offers pre-labeled diagrams to include with every MG5114A shipment or rebuild kit.
Off-Season Maintenance
If your vessel will be idle for several months—such as during winter layup, hurricane season haul-out, or dockside repair queue—it’s vital to take protective measures that prevent transmission wear or damage while at rest.
Draining Fluids
For long-term idle periods:
- Run the transmission until warm, then shut down.
- Drain all oil from the housing, cooler, and lines.
- Reinstall drain plugs with a thin coat of non-hardening thread sealant.
- Leave dipstick removed temporarily to allow internal vapor to escape for 24 hours, then reinsert.
- Store with dry internals, or fog with VCI oil for ultra-long storage.
Do NOT leave old, contaminated oil in the transmission—residual acids and moisture will cause internal corrosion.
Periodic Shaft Rotation
In gearboxes that remain idle for months at a time, internal clutch packs and bearings can “sit” in one spot. To prevent:
- Adhesion of clutch plates
- “Flat-spotting” of bearings
- Shaft corrosion from condensation
You should:
- Rotate the output shaft manually once every 30–60 days
- Turn the shaft at least 2–3 full revolutions in both directions
- If gear is installed, do this with transmission in neutral and engine off
Bonus: This also helps distribute any internal fogging oil or preservatives.
Off-Season Inspection Checklist
Here’s a routine checklist to protect the MG5114A during storage or seasonal downtime:
| Item | Action |
| Oil condition | Drain if dirty or aged over 12 months |
| Ports | Cap or plug all openings |
| External hardware | Apply corrosion inhibitor to bolts |
| Housing surface | Wipe down with VCI spray or fogging oil |
| Labeling | Attach notes for reactivation prep |
| Shaft rotation | Mark calendar reminders for 30-day intervals |
| Environmental exposure | Verify cover, pallet elevation, and humidity control |
Reactivating After Storage
When ready to bring the MG5114A back into service:
- Remove any desiccants or fogging materials
- Refill with fresh SAE 30 or SAE 40 oil
- Replace all seals and O-rings if more than 12 months have passed
- Run in neutral for 15–30 minutes and check for:
- Oil pressure
- Leaks
- Gear engagement smoothness
- Inspect oil again after 2 hours of use—check for color, smell, and consistency
Long-Term Storage: Best Practices Summary
| Practice | Description | Why It Matters |
| Seal all ports | Plug, cap, or tape all fluid and vent ports | Prevents contamination and insect ingress |
| Use VCI/fogging oil | Apply protective coating inside housing | Stops corrosion and clutch sticking |
| Store off ground | Use pallets or stands | Avoids moisture and condensation buildup |
| Label everything | Ports, hoses, shaft direction | Makes reassembly error-proof |
| Rotate shafts | Manually every 30–60 days | Keeps bearings and clutches from seizing |
Frequently Asked Questions
Q: Can I store the transmission outdoors under a tarp?
A: It’s not recommended. Moisture and condensation can build up under tarps. Always store indoors or use a breathable marine cover and elevated pallet.
Q: Should I store the transmission full of oil or drained?
A: For short-term storage (under 3 months), it’s okay to leave oil in. For long-term or seasonal storage, drain completelyand fog internals.
Q: What happens if I don’t rotate the shaft during storage?
A: Bearings can develop brinelling, and clutch discs may adhere to the plates—especially in humid environments.
Q: What if I’m shipping the unit overseas?
A: Use a sealed crate with VCI protection, label all ports, and photograph the condition before sealing. Diesel Pro Power can assist with export-ready packaging.
Final Thoughts on Long-Term Care for Your MG5114A
The Twin Disc MG5114A is a trusted and powerful marine transmission—but without proper storage and long-term care, even the most durable gearbox can suffer from preventable damage. Whether you’re shipping the unit, preparing for seasonal layup, or preserving a spare for fleet rotation, following these best practices ensures:
- Faster reactivation
- Lower repair costs
- Longer service life
- Better performance and reliability
Take the time to seal, label, and protect your MG5114A—and it will serve your vessel reliably when the next job calls.
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