Mercury Gearcase Drain Plug Gasket – Part 354 (5-Pack)
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Mercury Gearcase Drain Plug Gasket – Part 354
This genuine Mercury OEM drain plug gasket is a small but essential sealing washer used on the drain and fill screws of older Mercury outboard lower units and gearcases. It creates a leak-free seal that keeps gear lube in and water out. Sold in a convenient 5-pack — the right quantity for multiple services or keeping spares on hand.
Compatible Applications
- Older Mercury and Mariner outboard lower units using Part 354 drain plug gaskets
- Confirm fitment against your engine model and serial number — newer Mercury engines use the updated 8M0187157 blue seal
Part Details
- OEM Part Number: 354
- SKU: 530451
- Brand: Mercury / Quicksilver
- Type: Gearcase drain and fill plug gasket (sealing washer)
- System: Lower unit / gearcase
- Pack Quantity: 5 gaskets
- Condition: New OEM
Service Interval
Replace this gasket every time gear lube is changed. The gasket compresses on first use and should never be reused — reusing a spent gasket is a leading cause of gear lube leaks after service.
Technical FAQ
- How many gaskets do I need per service? Most lower units have two screws — a drain and a fill/vent — so use two gaskets per service. The 5-pack covers two full services with one spare.
- Is Part 354 the same as 8M0187157? No — Part 354 is the legacy gasket used on older Mercury outboards. The 8M0187157 blue seal is the current OEM replacement for newer engines. Check your engine’s service manual to confirm which part applies.
- Can I reuse the old gasket? No. These are one-time-use sealing washers. Reusing a compressed gasket risks an incomplete seal and gear lube leaks.
- What happens if I skip replacing the gasket? A missing or reused gasket can allow gear lube to seep out and water to enter the lower unit, leading to bearing and gear damage.
Related Parts
- MerCruiser Gearcase Drain Screw Seal – 8M0187157 (Blue) — current OEM replacement for newer engines
- Mercury MerCruiser Gear Lube Pump Kit – 8M0072135
- Mercury Lower Unit Seal Kit – 26-33144A2
Parts Desk Insights
Part 354 is the legacy drain plug gasket for older Mercury outboards — if you’re servicing a newer engine and this part doesn’t look right, check whether your engine uses the 8M0187157 blue seal instead. The most common mistake with drain plug gaskets is reusing the old one: these are one-time-use compressible washers, and a reused gasket is one of the most frequent causes of post-service gear lube leaks. The 5-pack is the right buy for anyone doing regular seasonal maintenance on one or more outboards — at this price point, there’s no reason to risk a leak by reusing a spent gasket. Always confirm your engine model and serial number if you’re unsure which drain gasket applies.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.