Lower Unit Seal Kit – Fits Suzuki V6 Outboard Motors (Replaces 25700-87D00)

$19.95

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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.).

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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 150–225 HP 2-stroke V6 outboard motors manufactured between 1986 and 2003. It provides all necessary seals for servicing the lower gearcase unit, ensuring a reliable, leak-free repair.

It serves as a direct replacement for Sierra part number 18-8335 and Suzuki OEM part number 25700-87D00.

Engineered for direct replacement of the original seals.
Provides a complete set of seals for lower unit service.
Covered by a standard manufacturer warranty against defects.

Part Number Matrix

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

Brand	Part Number
Suzuki	25700-87D00
Sierra	18-8335

Engine & Model Compatibility

Confirm your engine model/year in the table below.

This kit is confirmed to fit the following Suzuki V6 engines.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Suzuki	DT150	150	2-Stroke	1986–2003	25700-87D00	V6 engines
Suzuki	DT175	175	2-Stroke	1986–2003	25700-87D00	V6 engines
Suzuki	DT200	200	2-Stroke	1986–2003	25700-87D00	V6 engines
Suzuki	DT225	225	2-Stroke	1986–2003	25700-87D00	V6 engines

Technical Specs

Product Type: Lower Unit Seal Kit
Installation: Direct replacement
Dimensions: Height: 7.25 in; Width: 6.0 in; Length: 0.63 in;
Warranty: Standard manufacturer warranty
Other Technical Attributes: Complete seal kit for lower unit service

What’s in the Box

1 x Lower Unit Seal Kit (replaces Suzuki 25700-87D00)

Installation Notes

Drain the gear lube from the lower unit completely.
Remove the propeller assembly and unbolt the lower unit from the engine midsection.
Carefully disassemble the lower unit, propshaft, and driveshaft assemblies to access the seals.
Thoroughly clean all mating surfaces, removing any old sealant, debris, or corrosion.
Install the new seals, gaskets, and O-rings from the kit, applying marine grease where appropriate.
Reassemble all components, ensuring bolts are torqued to the manufacturer’s specifications.
Refill the gearcase with new, high-quality marine gear lube before operating.

Troubleshooting & FAQ

How do I know if this seal kit fits my Suzuki motor?

This kit is specifically for Suzuki V6 2-stroke outboard motors from 150 to 225 HP, built between 1986 and 2003. Please verify your engine model and year against the compatibility table. The OEM part number it replaces is 25700-87D00.

What are the signs my lower unit seals are failing?

Common symptoms include a milky, grey, or watery appearance in your gear lube, oil leaking from the propeller shaft area, or visible drips from the lower unit weep holes. Any sign of water intrusion requires immediate attention to prevent catastrophic gear failure.

How often should lower unit seals be replaced?

It is good practice to inspect your gear lube after every season or 100 hours of use. We recommend replacing the lower unit seals whenever the water pump is serviced (typically every 2-3 years) or immediately if you find evidence of water intrusion.

Is this kit the same as the OEM Suzuki part?

This is an aftermarket kit designed to meet or exceed original equipment manufacturer (OEM) specifications for fit, form, and function. It offers a cost-effective alternative to the Suzuki-branded part without compromising on quality.

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.

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