Sierra Oil Seal 18-2009 for MerCruiser R/MR/Alpha One and Alpha One SS Stern Drives

The Sierra 18-2009 is an oil seal engineered as a direct-fit component for MerCruiser stern drive units. It is installed within the stern drive housing to retain lubricating oil and keep water and contaminants out of the gear case, protecting internal gears and bearings from premature wear and moisture intrusion. One seal is required per stern drive installation.

This seal is designed for MerCruiser R/MR/Alpha One stern drives with a beginning serial number of 6225577 and up, MerCruiser Alpha One SS stern drives across all serial numbers, and MerCruiser I stern drives with serial numbers between 1534570 and 1684187. Confirm your stern drive model and serial number range before ordering to ensure correct fitment.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2009
• Product Type: Oil Seal
• Category: MerCruiser Parts
• Weight: 0.01 pounds
• UPC: 030999309556
• Quantity Required: 1 per stern drive
• Compatible Stern Drive Models: R/MR/Alpha One (Serial Number 6225577 and Up); Alpha One SS (All Serial Numbers); I (Serial Number 1534570 to 1684187)

Fitment

• MerCruiser R/MR/Alpha One - Serial Number 6225577 and Up
• MerCruiser Alpha One SS - All Serial Numbers
• MerCruiser I - Serial Number 1534570 to 1684187

Frequently Asked Questions

What is the Sierra 18-2009 oil seal used for? The Sierra 18-2009 is an oil seal installed in a MerCruiser stern drive housing to retain gear case lubricant and block water and debris from entering, protecting the internal gears and bearings.

Which MerCruiser stern drives fit the 18-2009 oil seal? Sierra 18-2009 fits MerCruiser R/MR/Alpha One stern drives with serial number 6225577 and up, MerCruiser Alpha One SS stern drives across all serial numbers, and MerCruiser I stern drives with serial numbers between 1534570 and 1684187.

How do I know if my stern drive is compatible with part number 18-2009? Check your stern drive model designation and serial number tag; 18-2009 is built for R/MR/Alpha One units serial 6225577 and up, all Alpha One SS units, and MerCruiser I units serial 1534570 to 1684187.

How many of the 18-2009 seal do I need per stern drive? One Sierra 18-2009 oil seal is required per stern drive installation.

How much does the 18-2009 oil seal weigh? The Sierra 18-2009 oil seal weighs 0.01 pounds.

Is the Sierra 18-2009 an OEM or aftermarket part? Sierra 18-2009 is an aftermarket replacement oil seal manufactured to fit the specified MerCruiser stern drive applications.

What is the UPC for the Sierra 18-2009 oil seal? The UPC for Sierra part number 18-2009 is 030999309556.

Does the 18-2009 seal fit Alpha One SS stern drives with any serial number? Yes, Sierra 18-2009 fits MerCruiser Alpha One SS stern drives across all serial numbers, not just a limited range.

Will 18-2009 fit a MerCruiser I stern drive outside the 1534570 to 1684187 serial range? No, for MerCruiser I stern drives the Sierra 18-2009 oil seal is specified for serial numbers between 1534570 and 1684187 only.

Is installation of the 18-2009 oil seal a job for a professional? Installing the Sierra 18-2009 oil seal involves disassembling the stern drive housing, so many boat owners have this done by a qualified marine mechanic to avoid damaging the seal or housing during installation.