Lower Unit Seal Kit – Fits Suzuki DT115/DT140 2-Stroke (Replaces 25700-94500)

$48.95

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Worry-free returns

You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Lower Unit Seal Kit is designed for Suzuki DT series 2-stroke outboard engines, including 115 HP and 140 HP models from all production years. It provides the essential seals and gaskets needed to service the gearcase and prevent water intrusion.

It serves as a direct replacement for Sierra part number 18-8338 and Suzuki OEM part number 25700-94500.

Engineered to meet or exceed OEM specifications for reliable performance.
Includes OEM-style gaskets and seals for a precise fit.
Installation is a straightforward mechanical process requiring basic tools.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Suzuki	25700-94500
Sierra	18-8338

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Suzuki outboards, this kit fits DT115 and DT140 2-stroke models across all years of manufacture.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Suzuki	DT115	115	2-Stroke	All years	25700-94500
Suzuki	DT140	140	2-Stroke	All years	25700-94500

Technical Specs

Product Type: Lower Unit Seal Kit
Installation: Mechanical installation, requires basic tools
Fitting Type: OEM-style gaskets and seals
Other Technical Attributes: Meets or exceeds OEM specifications
Product Dimensions: 7.13" H x 6.0" W x 0.88" L

What’s in the Box

High-Performance OEM Style Gaskets & Seals

Installation Notes

Disconnect the engine's battery and ensure the engine is securely positioned.
Place a drain pan under the lower unit and remove the drain and vent screws to empty the gear lube.
Unbolt and carefully remove the lower unit assembly from the engine's midsection.
Disassemble the gearcase as required to access the propeller shaft and driveshaft seals.
Using appropriate tools, carefully remove all old seals, o-rings, and gaskets. Clean the sealing surfaces thoroughly, avoiding scratches.
Install the new seals and gaskets from the kit. Lightly grease seals before installation to prevent damage.
Reassemble the gearcase components, ensuring all parts are torqued to manufacturer specifications.
Reinstall the lower unit onto the outboard motor.
Refill the gearcase with the correct type and amount of marine gear lubricant.
Replace the vent and drain screw gaskets, then securely tighten the screws. Check for leaks before returning to service.

Troubleshooting & FAQ

How do I know if this seal kit fits my engine?

This kit is specifically designed for all production years of Suzuki DT115 and DT140 2-stroke outboard models. Always cross-reference your OEM part number (25700-94500) to ensure a perfect match.

What are the signs of a failing lower unit seal?

The most common sign is "milky" or creamy-looking gear lube, which indicates water contamination. Other symptoms include visible oil leaks around the propeller shaft or driveshaft housing, or a persistent metallic smell from the gearcase.

Do I need special tools for installation?

While installation can be done with basic hand tools, specialized tools like a seal puller, bearing puller, and a press can make the job easier and reduce the risk of damaging the new seals or gearcase housing.

How often should lower unit seals be replaced?

It is best practice to inspect your gear lube after every season. Seals should be replaced immediately if you find water in the oil. Otherwise, they should be replaced as part of a major service or every 3-5 years, depending on usage and operating conditions.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost?

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns?

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

Payment & Security

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