Transom Bellows Seal Kit for MerCruiser Bravo I, II & III — Replaces 30-803100T1, 8M0095485, 18-8219

Product Details

This aftermarket Transom Bellows Seal Kit is designed for MerCruiser Bravo I, Bravo II, and Bravo III sterndrives. It provides the primary bellows, bearing, hose, gasket, O-ring, and clamping components used during a Bravo transom service, helping restore sealing around the sterndrive and reduce the risk of water intrusion.

The kit replaces or cross-references MerCruiser part numbers 30-803100T1 and 8M0095485. Catalog cross-references also identify Sierra 18-8219 as a transom seal kit reference for applicable Bravo and selected Blackhawk applications.

• Transom bellows service kit for MerCruiser Bravo I, II, and III drives
• Includes the principal bellows, gimbal bearing, water hose, gaskets, O-rings, and clamps listed below
• Aftermarket replacement; not manufactured by MerCruiser or Mercury Marine
• Verify the drive serial number, original component numbers, and photographs before ordering

Part Number Matrix

These are customer-facing OEM and aftermarket reference numbers associated with this replacement kit. Part-number references do not by themselves confirm every serial-number variation.

Engine & Model Compatibility

This is sterndrive fitment rather than outboard-engine fitment. Keep the model, year, and serial-number conditions together when confirming compatibility.

Technical Specs

Application

MerCruiser Bravo I, Bravo II, and Bravo III sterndrives

Primary OEM References

30-803100T1, 8M0095485

Aftermarket Reference

Sierra 18-8219

Gimbal Bearing

30-862540A3; catalog listings also reference 30-60794A3/A4 variations

U-Joint Bellows

86840A3

Shift Cable Bellows

74639

Exhaust Bellows

32734A3

Exhaust Tube

78458A1

Water Hose

32-43437

Mounting Gasket / O-Ring Kit

16755A1

Clamps

Bellows and hose clamps as supplied with the kit

What's in the Box

Kit contents are based on the component listing associated with the Bravo transom seal kit reference. Individual component markings may differ by production batch or supplier equivalent.

• Shift cable bellows — reference 74639
• Gimbal bearing — reference 30-862540A3
• U-joint bellows — reference 86840A3
• Exhaust bellows — reference 32734A3
• Exhaust tube — reference 78458A1
• Water hose — reference 32-43437
• Outdrive mounting gasket and O-ring kit — reference 16755A1
• Required bellows or hose clamps as supplied

Installation Notes

1. Disconnect the battery and remove the drive unit according to the applicable MerCruiser service procedure.
2. Confirm the drive model and serial number before disassembly.
3. Inspect the gimbal housing, transom assembly, mounting surfaces, and surrounding hardware for corrosion or damage.
4. Remove the old bellows, hose, gasket, O-rings, and clamps without damaging the mating surfaces.
5. Use the correct bearing puller and driver to remove the old gimbal bearing.
6. Clean and dry all mounting surfaces. Use only sealants and lubricants specified by the applicable service manual.
7. Install the replacement gimbal bearing squarely and fully seated.
8. Fit the U-joint, exhaust, and shift cable bellows in their correct locations and position the clamps according to the service manual.
9. Install the water hose, mounting gasket, and O-rings in the correct orientation and grooves.
10. Tighten clamps and fasteners to the manufacturer’s specified torque; do not overtighten.
11. Reinstall the drive, verify alignment, and torque the drive and transom hardware to specification.
12. Perform a controlled water test and inspect the bilge and transom area for leaks before normal operation.

Troubleshooting & FAQ

How do I know if my bellows need replacement?

Look for cracks, splits, hardening, abrasion, loose clamps, or signs of water intrusion. Bellows should be inspected during routine service and replaced when deterioration is found.

Can I reuse the old clamps?

Reuse is not recommended after removal. Clamps can lose tension or become distorted, so use the replacement clamps supplied with the kit when applicable.

Do I need special tools to replace the gimbal bearing?

Yes. A suitable gimbal-bearing puller and driver are recommended. Correct alignment and seating are essential to prevent bearing or housing damage.

Is this kit compatible with Alpha One drives?

No general Alpha One fitment should be assumed. The catalog identifies separate Alpha and Bravo transom seal kits, so Alpha One owners must verify the exact drive model and serial number against the required kit.

Does this kit include an OEM MerCruiser component?

No. This listing is for an aftermarket replacement kit. The OEM numbers are provided only as compatibility and replacement references.

Will it fit a Bravo X drive?

Do not rely on the Bravo name alone. Verify the complete drive designation, serial number, original bellows configuration, and component references before ordering.

How often should transom bellows be inspected?

Inspect them at least annually and whenever the drive is removed. Replace them sooner if cracking, splitting, hardening, clamp damage, or water intrusion is present.

Safety & Important Info

• Professional installation is recommended because drive removal, bearing replacement, alignment, and sealing affect safe operation.
• Confirm the complete model and serial-number condition before purchase; Bravo and Alpha applications use different service-kit configurations.
• Compare the original parts and photographs with the listed components before installation.
• This is an aftermarket replacement and is not an OEM MerCruiser or Mercury Marine kit.

About Sea Sierra

• Pro-Grade Standards — We supply marine replacement parts selected for dependable service in real-world operating conditions.
• Practical Fitment Information — We provide OEM and aftermarket reference numbers to help customers compare their original parts.
• Manufacturer-Direct Value — We focus on useful replacement solutions without overstating compatibility or package contents.