Volvo Penta Lower Gear Housing O-Ring - 3889784
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The Volvo Penta 3889784 Lower Gear Housing O-Ring is a genuine OEM molded sealing ring used in compatible Volvo Penta sterndrive gear housing assemblies. This low-profile seal helps maintain gearcase oil integrity and reduce the risk of water intrusion where lower gear housing and intermediate housing components mate.
This part is commonly replaced whenever the lower gear housing is separated, inspected, resealed, or serviced as part of a gearcase pressure-test repair.
Key Features
- Genuine Volvo Penta lower gear housing sealing O-ring.
- Volvo Penta part number: 3889784.
- Replaces legacy Volvo Penta part number: 3841966.
- Component type: molded O-ring / mounting gasket.
- Used for compatible sterndrive lower gear housing sealing applications.
- Helps retain gear lubricant and block water intrusion.
- Low-profile static seal design.
- Approximate weight: 0.01 lb / 4.5 g.
- Designed for marine gearcase service environments.
Drive Compatibility
Common application context includes compatible Volvo Penta sterndrive gear housing assemblies where 3889784 or superseded number 3841966 is listed in the parts diagram.
Verify use on:
- Volvo Penta sterndrive lower gear housings.
- Intermediate housing / lower gear housing sealing locations.
- Gearcase reseal and pressure-test service.
- Sterndrive service repairs where the parts schematic calls for this O-ring.
Use this seal only where the Volvo Penta parts diagram for the exact drive model and serial number confirms 3889784.
Serial Number Fitment Notice
Confirm fitment by Volvo Penta drive model, serial number, gear housing style, diagram location, and companion sealing parts before ordering. Volvo Penta sterndrives can use different seals depending on the drive family, production range, gear housing revision, and service history.
When servicing the gear housing, inspect related seals and gaskets at the same time, including nearby cover gaskets, shaft seals, drain/fill plug seals, and any mating-surface O-rings listed in the same assembly.
When This Part Needs Replacement
Replace this O-ring whenever the gear housing joint is opened, when resealing the lower gear unit, after a failed pressure or vacuum test, or when there are signs of gear oil leakage, water intrusion, flattened sealing surfaces, cuts, swelling, hardening, or distortion.
A low-cost O-ring should not be reused if it has already been compressed in a gearcase joint.
Installation Notes
Clean the aluminum sealing groove and mating surfaces completely before installation. Remove old oil, sealant residue, corrosion, grit, and marine growth from the groove so the new O-ring can sit flat without twisting or pinching.
Lightly lubricate the O-ring with clean marine gear oil before assembly. Seat the O-ring evenly in the groove, align the housings carefully, and tighten fasteners according to the Volvo Penta service procedure. After assembly, pressure-test and vacuum-test the gearcase before refilling with gear lubricant.
Alternate / Superseded Part Numbers
- Volvo Penta 3889784 — current supplied part number
- Volvo Penta 3841966 — legacy / superseded reference
- 3889784 O-Ring — common catalog description
- Lower Gear Housing Mounting Gasket — common application description
Parts Desk Insight
This is a small seal with an important job. If the O-ring is pinched, reused, or installed into a dirty groove, the gearcase can fail a pressure test or allow water into the oil. When a Volvo Penta lower gear housing is apart, replacing the related seals at the same time is usually the cleanest way to protect the gearset, bearings, and shafts from water contamination.
Shipping: Ships same or next day for fast Canada wide shipping. ⚓
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 3–4 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
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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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