OMC King Cobra Water Pump Repair Kit | Sierra 18-3469

Sierra 18-3469 OMC King Cobra Water Pump Repair Kit | 1992–1995 | With Impeller Cup/Cam Housing | Replaces OMC 3854661

The Sierra #18-3469 is a water pump repair kit for OMC King Cobra sterndrive units from 1992 to 1995. Includes the impeller, impeller cup/cam housing, wear plate, gasket, and O-ring — all internal water pump components required for a complete pump rebuild. Does not include the outer pump body/volute housing. Replaces OMC 3854661.

Part Details:

• Part Number: 18-3469 (Sierra)
• SKU: SIERRA-18-3469
• Manufacturer: Sierra
• Type: Water Pump Repair Kit — with Impeller Cup/Cam Housing
• Fits: OMC King Cobra sterndrive, 1992–1995
• Kit Includes: Impeller, impeller cup/cam housing, wear plate, gasket, O-ring
• Not Included: Outer pump body/volute housing
• Replaces: OMC 3854661
• Condition: New

Cross-Reference — Replaces:

• OMC: 3854661

Additional Information

OMC King Cobra — 1992–1995 Water Pump Application:

The OMC King Cobra was OMC's V8-capable sterndrive system produced from the mid-1980s through 1993 when OMC discontinued the King Cobra line. The 18-3469 covers King Cobra drives from 1992 to 1995 — the final production years. King Cobra water pump parts have become increasingly difficult to source as OEM stock has been depleted; the Sierra 18-3469 is the current aftermarket repair kit for these drives. Confirm your drive's year and model designation (King Cobra, not OMC Cobra or OMC Stern Drive) before ordering.

Kit Contents — What’s Included and What’s Not:

The Sierra 18-3469 includes the complete internal water pump service components:

• Impeller — the neoprene vane impeller that moves raw water through the cooling circuit
• Impeller cup/cam housing — the inner housing that contains the impeller and creates the eccentric cavity required for impeller pumping action
• Wear plate — the flat plate the impeller runs against; inspect for scoring or grooving at every service
• Gasket — seals the pump housing mating surface
• O-ring — seals the pump assembly at the O-ring seating surface

The outer pump body/volute housing is not included. If the outer housing is damaged or corroded, it must be sourced separately. Inspect the outer housing during pump disassembly and replace if worn beyond the service limit specified in the OMC King Cobra service manual.

Wear Plate Inspection — Critical for Pump Performance:

The wear plate is the flat surface the impeller blades run against to create pumping pressure. A worn, scored, or grooved wear plate reduces pump efficiency even with a new impeller — the impeller blades cannot maintain the contact needed to push water effectively. Always inspect the wear plate when servicing the water pump. Replace the wear plate if any scoring, grooving, or pitting is visible. The 18-3469 includes a new wear plate, ensuring both the impeller and its mating surface are renewed at the same service.

Impeller Cup/Cam Housing — Why It Matters:

The impeller cup (cam housing) is the inner housing that creates the eccentric bore the impeller rotates within. The eccentric offset between the impeller center and the cam housing bore is what generates the pumping action — as the impeller rotates, the blades flex to conform to the cam housing bore, sweeping water from inlet to outlet. A worn or corroded cam housing reduces the impeller-to-bore contact that drives pumping efficiency. Including the cam housing in the 18-3469 kit ensures both the impeller and the housing it operates in are replaced together.

Water Pump Service Interval — King Cobra:

OMC recommended annual water pump impeller service for King Cobra sterndrive units. Given the age of these drives (1992–1995), annual service is especially important — neoprene impeller blades harden with age regardless of hours, and the cam housing and wear plate are subject to corrosion over storage periods. Service the water pump at the start of each season and inspect all kit components.

Inspect the Raw Water Circuit After Impeller Failure:

If the impeller has failed with broken blade fragments, flush and inspect the entire raw water cooling circuit before reassembly. Blade fragments can lodge in the thermostat housing, heat exchanger, or exhaust manifold water passages, blocking flow even after the pump is rebuilt. Remove all fragments before returning the drive to service.

Installation Notes:

• Confirm drive is OMC King Cobra 1992–1995 before ordering — not for OMC Cobra or other OMC sterndrive models
• Inspect outer pump housing for damage or corrosion before reassembly — not included in this kit
• Inspect wear plate and cam housing from old kit; replace all components with new kit parts
• Lubricate impeller with dish soap or glycerin before installation — not petroleum-based lubricant
• Install impeller with blade curve in correct rotational direction per OMC King Cobra service manual
• Flush raw water circuit for blade fragments if old impeller failed
• Pressure test cooling system after reassembly before returning to service

Frequently Asked Questions

1. What years of OMC King Cobra does this kit fit?
1992 to 1995. Confirm your drive is an OMC King Cobra (not OMC Cobra or other OMC sterndrive) from this year range before ordering.

2. Does this kit include the outer pump housing?
No — the 18-3469 includes the impeller, impeller cup/cam housing, wear plate, gasket, and O-ring. The outer pump body/volute housing is not included. Inspect the outer housing during disassembly and source separately if damaged.

3. Why is the cam housing included in this kit?
The cam housing is the inner eccentric bore the impeller runs within — it directly affects pumping efficiency. Including it in the repair kit ensures both the impeller and its working bore are renewed together, rather than installing a new impeller in a worn cam housing that will reduce pump performance.

4. What OMC part number does this kit replace?
OMC 3854661.

5. How often should I service the water pump on my King Cobra?
Annually, at the start of each season. Given the age of these drives, neoprene impeller blades harden over time regardless of hours — annual inspection and replacement is recommended even for low-use vessels.