Sierra Water Pump Base Seal 18-7170-9, Bell Housing Seal for MerCruiser R/MR/Alpha I Stern Drives, Pack of 5

The Sierra Water Pump Base Seal 18-7170-9 is a bell housing oil seal used in the gimbal housing of MerCruiser R/MR/Alpha I stern drives. This seal sits at the base of the water pump assembly where the drive shaft passes through the gimbal housing, helping to keep water out of the bell housing area and maintain the seal integrity of the drive unit during operation. It is designed as a direct-fit replacement for the bell housing seal position (BH) on applicable R/MR/Alpha I stern drives beginning at serial number 6225577 and up.

This seal is sold as an O-ring style component and is priced and packaged per unit of 5, making it a practical option for shops or owners who want spares on hand for routine gimbal housing service or water pump rebuilds. Keeping the bell housing seal in good condition is a key part of preventing water intrusion into the gimbal housing during water pump maintenance, and replacing it whenever the gimbal housing or water pump is serviced is standard practice.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-7170-9
• Product Name: Water Pump Base Seal
• Seal Type: Bell Housing Seal (BH)
• Location: Gimbal Housing
• Pack Size: Package of 5
• Weight: 0.03 pounds
• Applicable Stern Drive Model: R/MR/Alpha I
• Beginning Serial Number: 6225577 and up

Fitment

• MerCruiser R/MR/Alpha I stern drives, beginning serial number 6225577 and up

Frequently Asked Questions

What is the Sierra 18-7170-9 seal used for? The Sierra 18-7170-9 is a bell housing seal that fits into the gimbal housing of a MerCruiser R/MR/Alpha I stern drive, sealing the area where the water pump drive shaft passes through the gimbal housing.

Which stern drives does part 18-7170-9 fit? This seal fits MerCruiser R/MR/Alpha I stern drives beginning at serial number 6225577 and up.

How many seals come in a package? The 18-7170-9 bell housing seal is sold in a package of 5 units, so you receive 5 seals per order.

How much does the 18-7170-9 seal weigh? Each package of the Sierra 18-7170-9 seal weighs 0.03 pounds.

Where in the gimbal housing does this seal install? It installs in the bell housing (BH) position within the gimbal housing on applicable MerCruiser R/MR/Alpha I stern drives.

Is 18-7170-9 an OEM or aftermarket part? The 18-7170-9 is a Sierra-branded replacement seal designed to fit the bell housing position on MerCruiser R/MR/Alpha I stern drives from serial number 6225577 and up.

When should this seal be replaced? This bell housing seal is typically replaced whenever the gimbal housing or water pump on the applicable MerCruiser R/MR/Alpha I stern drive is serviced, to maintain a proper seal against water intrusion.

Does 18-7170-9 fit any serial number of R/MR/Alpha I drives? No, this seal applies to MerCruiser R/MR/Alpha I stern drives starting at serial number 6225577 and up; earlier serial numbers are not covered by this part.

Is this a rubber O-ring style seal? Yes, the Sierra 18-7170-9 is supplied as an O-ring style seal, packaged 5 per unit.

Can I buy the 18-7170-9 seal individually instead of a 5-pack? The 18-7170-9 seal is sold only as a package of 5 units.