Sierra 18-8205 - Alpha One Transom Seal Kit, Exhaust Tube

Sierra 18-8205 - R, MR and Alpha One Transom Seal Kit with Exhaust Tube

Plan transom service around the components your drive actually uses. Sierra 18-8205 groups an exhaust tube, U-joint bellows, water hoses, clamps, a greasable gimbal bearing, gasket mounting kit and shift lever for listed Mercruiser R, MR and Alpha One stern-drive applications. The exhaust tube and serviceable bearing are important selection details, not interchangeable descriptions for every Alpha transom kit.

Part Specifications

• Part Number: 18-8205
• Listed Drive Families: Mercruiser R, MR and Alpha One with exhaust-tube configuration
• Exhaust Component: Exhaust tube
• Gimbal Bearing: Greasable type
• Listed Kit Contents: Exhaust tube, U-joint bellows, water hoses, clamps, greasable gimbal bearing, gasket mounting kit and shift lever
• Replaces Mercury: 30-803098T1
• Additional Listed Cross-References: OMC/Johnson/Evinrude 775492; Mallory 9-72901

If a sealed-bearing service option is required, compare the Sierra 18-8213 R, MR and Alpha One transom kit. Its catalog listing specifies a sealed gimbal bearing and an exhaust bellows, whereas 18-8205 lists a greasable bearing and exhaust tube. Confirm the entire kit configuration before selecting between them.

Confirm Fitment Before Ordering

Use the parts diagrams available on our website to identify your transom assembly and required service components. Or send us your engine and stern-drive model and serial numbers by email, text or live chat, and we'll confirm fitment before ordering. Include the transom assembly identification and whether an exhaust tube or bellows is installed, particularly if the drive or transom components have been changed.

Additional Information

• Vendor: Sierra
• Part Number: 18-8205
• OEM Cross-Reference: Mercury 30-803098T1; OMC/Johnson/Evinrude 775492
• Kit Contents: Exhaust tube, U-joint bellows, water hoses, clamps, greasable gimbal bearing, gasket mounting kit and shift lever

Installation Notes

Refer to the applicable Mercruiser service manual for transom service, component placement, bearing lubrication, drive alignment, fastening and specified watertightness checks.

Frequently Asked Questions

Q: Does this kit include an exhaust tube or exhaust bellows?
A: Sierra 18-8205 lists an exhaust tube. Do not assume that a kit described with an exhaust bellows has identical contents or configuration.

Q: Is the included gimbal bearing sealed?
A: No. The listed bearing is greasable. The linked 18-8213 kit lists a sealed bearing but also specifies an exhaust bellows, so compare both differences before ordering.

Q: Does the Alpha One name establish Alpha One Gen II fitment?
A: No Gen II fitment is established here. The listed families are R, MR and Alpha One; verify the drive and transom serial-specific parts diagrams.

Q: Does the OMC cross-reference mean this fits every OMC stern drive?
A: No. A cross-reference number is not a broad drive-family fitment claim. Match the required reference and actual transom configuration.

Q: Does one kit guarantee that no additional service items will be needed?
A: No. Compare the listed contents with the planned repair and the condition of the existing assembly. Tools, consumables and other damaged components should not be assumed included.