Sierra 18-2772-1 SX Cobra Transom Seal Kit | OMC & Volvo Penta SX | Not for SX-A | Replaces Mallory 9-72931

Sierra 18-2772-1 — SX Cobra Transom Seal Kit | OMC & Volvo Penta SX Cone Clutch Sterndrives | Not for SX-A

Sierra 18-2772-1 transom seal kit for OMC and Volvo Penta SX cone clutch sterndrives. Not for SX-A drives — confirm your sterndrive model before ordering. Kit includes gimbal bearing, exhaust bellows, U-joint bellows, water seal, and hose clamp. Water intake hose is not included — hoses differ between models and must be sourced separately. Replaces Mallory 9-72931 and Sierra 18-2772 and 18-2786.

Important — confirm before ordering:

• Not for SX-A drives — for standard OMC and Volvo Penta SX cone clutch sterndrives only
• Water intake hose not included — must be sourced separately (differs by model)

Confirm Fitment Before Ordering

Confirm your sterndrive is an OMC or Volvo Penta SX cone clutch model — this kit does not fit SX-A drives. Contact us with your sterndrive model and serial number by email, text, or live chat to verify 18-2772-1 is the correct transom seal kit for your application.

Part Specifications

• Sierra Part Number: 18-2772-1
• Type: Transom seal kit
• Application: OMC and Volvo Penta SX cone clutch sterndrives
• Not For: SX-A drives
• Kit Contents:
  • Gimbal bearing
  • Exhaust bellows
  • U-joint bellows
  • Water seal
  • Hose clamp
• Not Included: Water intake hose (differs between models — must be sourced separately)
• Replaces: Mallory 9-72931; Sierra 18-2772, 18-2786
• Vendor: Sierra International

Additional Information

• Vendor: Sierra International
• Part Number: 18-2772-1
• OEM Cross-Reference: Replaces Mallory 9-72931; Sierra 18-2772, 18-2786
• Application: OMC & Volvo Penta SX cone clutch sterndrives — not for SX-A
• Kit Contents: Gimbal bearing, exhaust bellows, U-joint bellows, water seal, hose clamp
• Not Included: Water intake hose

Installation Notes

Install following the applicable OMC or Volvo Penta service manual for the SX sterndrive transom service.

Frequently Asked Questions

Q: How do I confirm this kit fits my sterndrive?
A: Sierra 18-2772-1 fits OMC and Volvo Penta SX cone clutch sterndrives. It does not fit SX-A drives. Locate your sterndrive model and serial number on the sterndrive ID tag and contact us by email, text, or live chat to confirm fitment before ordering.

Q: What is the difference between SX and SX-A drives?
A: The SX-A is an updated version of the OMC/Volvo Penta SX sterndrive with design differences that require different service parts. The 18-2772-1 kit is for the standard SX cone clutch sterndrive only. If your drive is an SX-A, you will need a different transom seal kit. Contact us by email, text, or live chat with your sterndrive serial number to identify your model.

Q: Why is the water intake hose not included?
A: The water intake hose routing differs between SX sterndrive models, so a single universal hose cannot be included in the kit. You must source the correct water intake hose for your specific model separately. Contact us by email, text, or live chat with your sterndrive model for help identifying the correct hose.

Q: What does this kit replace?
A: Sierra 18-2772-1 directly replaces Mallory 9-72931 and supersedes earlier Sierra part numbers 18-2772 and 18-2786. If your service documentation references any of these numbers, 18-2772-1 is the current replacement.

Q: Should I replace the gimbal bearing and all bellows at the same time?
A: Yes — whenever the transom is opened for sterndrive service, replace the gimbal bearing and all bellows together. The labor to access these components is the same whether you replace one or all, and leaving worn components in place risks a repeat teardown. The 18-2772-1 kit includes everything needed for a complete transom seal service except the water intake hose.