Sierra 18-2756 U-Joint Bellows for Mercruiser Bravo I/II/III and Blackhawk Stern Drives

The Sierra 18-2756 U-Joint Bellows is a molded replacement boot that seals the U-joint housing on select MerCruiser stern drives, keeping water out of the drive shaft area and gear lubricant in. It is built from a combination of plastic and rubber for flexibility at the joint while withstanding constant exposure to water and marine grease. The bellows is finished in black and ships as a single unit, ready to install as part of routine stern drive maintenance or as a replacement when the original bellows has cracked, hardened, or begun to leak.

This bellows is designed for MerCruiser Bravo I, Bravo II, and Bravo III drives built 1988 and newer with serial number 0B664190 and up, and for MerCruiser Blackhawk drives from 1994-1995 with serial number 0F18677 and up. On both drive families it is used together with the corresponding upper drive bellows and the shared middle bellows as part of a full bellows replacement, which is the standard practice anytime one bellows on the drive is replaced. Keeping the U-joint bellows in good condition is important preventive maintenance, since a torn or deteriorated bellows can allow water intrusion that leads to corrosion and premature U-joint or gimbal bearing failure.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2756
• Material: Plastic, Rubber
• Construction Type: Molded
• Color: Black
• Weight: 0.68 pounds
• Number of Items: 1
• UPC: 030999621542

Fitment

• Mercruiser Bravo I/II/III, 1988 & Newer, S/N 0B664190 & Up
• Mercruiser Blackhawk, 1994-1995, S/N 0F18677 & Up

Frequently Asked Questions

What does the Sierra 18-2756 U-Joint Bellows fit? It fits Mercruiser Bravo I/II/III stern drives built 1988 and newer with serial number 0B664190 and up, and Mercruiser Blackhawk drives from 1994-1995 with serial number 0F18677 and up.

What is a U-joint bellows used for? The U-joint bellows, part number 18-2756, is a molded boot that seals the U-joint housing on the stern drive, keeping water out and lubricant in around the U-joint area.

What is the 18-2756 bellows made of? It is molded from a combination of plastic and rubber, finished in black, giving it the flexibility needed at the joint while standing up to constant water and grease exposure.

How much does the 18-2756 U-Joint Bellows weigh? The Sierra 18-2756 U-Joint Bellows weighs 0.68 pounds.

How many bellows come in the package? One U-Joint Bellows, part number 18-2756, ships per package.

Do I need to check my drive's serial number before ordering? Yes. The 18-2756 bellows applies to Bravo I/II/III drives from S/N 0B664190 and up and Blackhawk drives from S/N 0F18677 and up, so confirming your drive's serial number ensures correct fitment.

Should the U-joint bellows be replaced with the other drive bellows? It is standard practice to replace all of the stern drive bellows together, since the 18-2756 U-joint bellows works alongside the drive's other bellows and they tend to wear out around the same time.

What are signs the U-joint bellows needs to be replaced? Cracking, hardening, or splitting in the bellows material, or visible water intrusion in the drive shaft area, indicate the U-joint bellows should be replaced.

Is the Sierra 18-2756 bellows a Mercruiser Blackhawk part or a Bravo part? It is used on both: Mercruiser Bravo I/II/III drives (1988 & Newer, S/N 0B664190 & Up) and Mercruiser Blackhawk drives (1994-1995, S/N 0F18677 & Up).

What color is the 18-2756 U-Joint Bellows? The bellows is black.