Quicksilver 30529 Bearing-Carrier O-Ring | Mercury MerCruiser OEM — 5-Pack
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Part Details
- Part Number: 30529 / 25-30529
- Brand: Quicksilver / Mercury Marine (Genuine OEM)
- Official Product Type: Bearing-Carrier O-Ring
- Sierra Cross-Reference: 18-7171-9
- O-Ring Size: 1.925 in. ID × 0.103 in. cross-section (approx. 48.9 mm × 2.6 mm)
- System: Gear housing — bearing carrier sealing
- Package Quantity: 5 O-rings
- UPC: 745061075634
What This Part Is
Quicksilver 30529 (full Mercury part number 25-30529) is a genuine OEM bearing-carrier O-ring used in Mercury outboard and MerCruiser gear housings where this number is specified in the parts diagram. It seals the bearing carrier to the surrounding gear housing bore, preventing gear-lube loss and water intrusion into the lower unit. This listing is for a 5-pack.
Compatible Applications
Fitment is confirmed by the parts diagram for your specific engine or drive. Documented applications include:
- Mercury outboard 7.5 HP gear housing — bearing carrier assembly
- Mercury outboard 9.8 HP / Merc 110 gear housing — bearing carrier assembly
- Additional Mercury outboard and MerCruiser assemblies where the diagram specifies 25-30529
Always confirm 25-30529 in the parts diagram for your exact model, serial number, and gear-housing assembly before ordering. Similar bearing-carrier O-rings can differ in diameter and cross-section, and those small differences affect sealing.
O-Ring Dimensions
- Inside Diameter: 1.925 in. / approx. 48.9 mm
- Cross-Section: 0.103 in. / approx. 2.6 mm
When to Replace
Replace the O-ring any time the bearing carrier is removed, or if the existing seal shows:
- Flattening or permanent compression set
- Cuts, nicks, or tearing
- Hardening or loss of elasticity
- Swelling or distortion
- Gear-lube seepage around the bearing carrier
- Damage from disassembly
Reusing a compressed or damaged O-ring risks gear-lube leakage or water intrusion into the gearcase.
Installation Notes
- Clean the O-ring groove and bearing-carrier sealing surface before fitting the new seal
- Inspect the carrier and housing bore for corrosion, scoring, or debris
- Lubricate the O-ring with the lubricant specified in the applicable Mercury service procedure
- Seat the O-ring fully in its groove — ensure it does not twist or pinch as the carrier is installed
- If the housing has shown water contamination, inspect the propeller-shaft seals and other carrier seals during the same service
Cross-Reference Part Numbers
- Mercury / Quicksilver: 30529 / 25-30529
- Sierra: 18-7171-9 (commonly supplied as a 5-pack replacement)
- UPC: 745061075634
Related Parts
- Browse Mercury MerCruiser / Quicksilver Gaskets & Seals for all sealing components
- Browse Marine Gaskets, Seals & O-Rings
Parts Desk Insights
Best use case: The 5-pack format is ideal for a complete lower-unit service where multiple O-rings of the same size are replaced in one job, or for keeping service stock on hand for repeat gearcase work. Replacing the bearing-carrier O-ring any time the carrier is already out adds minimal cost and eliminates the need to reopen the lower unit for a gear-lube leak.
Common issue: An O-ring that looks fine on the bench may already be permanently compressed and will not seal reliably on reassembly. Always install a fresh 30529 — never reuse the old seal. Also confirm the part number against the current diagram for your serial number; if the engine or drive has been updated, the diagram may reference a superseded or replaced number.
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.