Sierra O-Ring 18-7158 for Mercruiser Bravo I/II Stern Drives (S/N B664190 and Up)

The Sierra O-Ring 18-7158 is a replacement drive seal designed for Bravo I and Bravo II stern drives with beginning serial number B664190 and up. This O-ring is used as part of the stern drive gearcase seal set and is installed one per drive during gearcase service or reassembly to maintain a proper seal at the drive housing.

Using the correct O-ring during stern drive service helps prevent water intrusion and lubricant loss at the sealing surface. Because stern drive seals are matched to specific serial number ranges, confirming your drive's serial number against the range listed below ensures you install the correct part for your unit.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-7158
• Product Type: O-Ring
• Category: Mercury Outboard O-Rings & Seals
• Weight: 0.02 pounds
• Quantity per Stern Drive: 1
• UPC: 808282259693

Fitment

• Bravo I/II Stern Drive, beginning serial number B664190 and up

Frequently Asked Questions

What is the Sierra 18-7158 O-Ring used for? The Sierra 18-7158 is a replacement O-ring used in the gearcase seal set on Bravo I and Bravo II stern drives, installed one per drive.

Which stern drives fit the 18-7158 O-ring? This O-ring fits Bravo I/II stern drives with a beginning serial number of B664190 and up.

How many 18-7158 O-rings does one stern drive need? One Sierra 18-7158 O-ring is required per stern drive.

How do I know if my stern drive uses the 18-7158 O-ring instead of a different Sierra seal? Check your Bravo I/II stern drive's serial number; the 18-7158 O-ring applies to units with beginning serial number B664190 and up, so drives outside that range may require a different Sierra part.

How much does the Sierra 18-7158 O-ring weigh? The Sierra 18-7158 O-ring weighs 0.02 pounds.

Is the Sierra 18-7158 a genuine Sierra part or an aftermarket equivalent? The 18-7158 is a Sierra-branded replacement part sold under Sierra's own part number for Bravo I/II stern drive service.

Where on the stern drive does the 18-7158 O-ring install? It is installed as part of the gearcase seal assembly on Bravo I/II stern drives during service or reassembly.

Is the Sierra 18-7158 O-ring sold individually or in a kit? The Sierra 18-7158 is sold as a single O-ring, with one required per Bravo I/II stern drive.

Does the 18-7158 O-ring fit Bravo III stern drives? No, the Sierra 18-7158 O-ring is designated for Bravo I/II stern drives with serial number B664190 and up; other Bravo models use different Sierra seal part numbers.