Sierra 18-1728 Bellow Flange Ring for MerCruiser Alpha One Gen II (1991 & Up)

The Sierra 18-1728 is a rubber bellow flange ring built for MerCruiser Alpha One (Gen II) sterndrives (1991 and up). This white rubber ring seals and reinforces the flange area of the exhaust/drive bellow assembly, helping maintain a watertight connection between the transom and the sterndrive unit. As a wear component in the sterndrive's bellows system, it is a part boat owners typically replace during routine bellows maintenance or when performing a full bellows kit replacement, since rubber components in this location are exposed to constant flexing, saltwater or freshwater immersion, and engine vibration over time.

Sierra manufactures this flange ring to meet or exceed the specifications of the original equipment part it is designed to work with, and Sierra supplies parts to OEM engine manufacturers and boat builders as part of its regular production. The compact, lightweight ring is easy to handle during installation and is sized specifically for Alpha One (Gen II) applications, so boat owners working on this sterndrive series can source a correctly fitted replacement flange ring rather than a generic substitute.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-1728
• Material: Rubber
• Color: White
• Weight: 0.01 pounds
• UPC: 808282295073
• Fit Type: Universal Fit within stated application

Fitment

• MerCruiser Alpha One (Gen II), 1991 & Up

Frequently Asked Questions

What boats and drives does the Sierra 18-1728 fit? The Sierra 18-1728 bellow flange ring is designed for MerCruiser Alpha One (Gen II) sterndrives, 1991 and up.

What material is the 18-1728 flange ring made of? It is made of white rubber, a material chosen for its flexibility and ability to hold a seal in the bellows flange area.

How much does the Sierra 18-1728 weigh? This flange ring weighs 0.01 pounds, reflecting its small, lightweight construction.

Is the Sierra 18-1728 an OEM or aftermarket part? The 18-1728 is a Sierra-manufactured part engineered to meet or exceed the specifications of the original equipment part it replaces.

What is the UPC for the Sierra 18-1728 bellow flange ring? The UPC for this part is 808282295073.

When would I need to replace this flange ring? Replacement is typically needed during sterndrive bellows maintenance, since rubber components at the flange are subject to ongoing flexing and water exposure.

Does the 18-1728 fit older MerCruiser Alpha One models before Gen II? No fitment is stated for MerCruiser Alpha One models prior to the Gen II, 1991-and-up application; only that range is confirmed for the 18-1728.

What color is the Sierra 18-1728 bellow flange ring? The ring is white.

Is this a universal-fit part? The Sierra 18-1728 is listed as a universal fit within its stated MerCruiser Alpha One (Gen II), 1991 & Up application.

Does Sierra stand behind the 18-1728 with a warranty? Yes, the Sierra 18-1728 bellow flange ring is covered by a limited warranty.