Quicksilver Gear Housing Vent Screw 28653 | #10-32 × 1/4 in. | Mercury MerCruiser OEM | Pack of 5
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Quicksilver OEM Gear Housing Vent Screw — Part No. 28653 / 10-28653
- Part Number: 28653
- Service Format: 10-28653
- Brand: Quicksilver (Genuine Mercury Marine OEM)
- Type: Gear Housing Vent Screw
- Thread: #10-32 (UNF fine thread)
- Nominal Thread Diameter: 0.190 in. / 4.83 mm
- Length: 0.25 in. / 6.35 mm
- Thread Pitch: 32 TPI / approx. 0.79 mm
- Pack Quantity: 5 screws
- GTIN / UPC: 745061133105
- System: Lower Unit / Gear Housing — vent hardware
What This Part Does
This genuine OEM screw plugs the vent port on Mercury outboard gear housings and lower units. The vent screw allows trapped air to escape during gear-lube filling, then seals the housing once the correct lube level is reached. Used together with the appropriate sealing washer (Mercury 19643, which supersedes 20262), it prevents gear-lube leakage at the vent location during operation.
Important distinction: Do not confuse 28653 with Mercury’s larger gear-lube drain/fill plug (79953-series). The 28653 is a small #10-32 × 0.25 in. vent screw — much smaller than the drain plug. Confirm the correct position in your lower-unit diagram before ordering.
Pack note: Mercury diagrams typically show one vent screw per gear housing. The 5-piece pack is a retail convenience format — useful for service shops or keeping spares aboard.
Compatible Applications
- Mercury 4 HP 2-stroke gear housings
- Mercury 9.8 HP gear housings
- Mercury 10 HP / XR10 gear housings
- Mercury 60J gear housings
- Mercury 80 HP 3-cylinder gear housings
- Numerous additional legacy Mercury outboard gearcase assemblies
- Any Mercury or MerCruiser gear housing where the parts diagram specifies 28653 / 10-28653
Confirm the exact diagram position using your engine model and serial number before ordering.
Recommended Service Pairing
Mercury commonly pairs 28653 with vent-screw seal 19643 (supersedes 20262). Inspect or replace the sealing washer any time the vent screw is removed — the washer provides the actual fluid seal, so do not rely on thread tightening alone.
When to Replace
- Screw threads are stripped, damaged, or corroded
- Screw head is rounded or distorted and cannot be tightened properly
- Corrosion prevents the screw from seating correctly
- Incorrect hardware was installed in a previous service
- Lower-unit gear-lube service calls for hardware renewal
Installation Notes
- Always install a new sealing washer (19643) with the vent screw — do not reuse the old washer
- Inspect the gear-housing threads for corrosion or damage before installing the new screw
- Thread the screw in by hand before applying torque to avoid cross-threading the small #10-32 thread
- Tighten to the Mercury service specification — do not over-tighten this small screw
- Check for gear-lube seepage at the vent location after completing the lube service
Related Products
- Fasteners & Mounting Hardware
- Mercury MerCruiser Gaskets & Seals
- Mercury MerCruiser Engine Maintenance Parts
Parts Desk Insights
The #10-32 thread and 0.25 in. length make 28653 the small vent screw — easy to tell apart from the much larger drain/fill plug, but easy to lose during a gear-lube service. The most common issues are cross-threading on installation (the fine #10-32 thread strips easily if started off-angle) and skipping the sealing washer renewal. Always replace the 19643 washer when the vent screw comes out. Keeping the 5-piece pack in the service kit means you’ll always have a spare if one gets dropped overboard or the threads get nicked.
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.
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