863404T Mercruiser Water Pump Pulley | Genuine Used Part

🔧 Product Description

Genuine MerCruiser Circulating Water Pump Pulley - Part Number: 863404T

A genuine used MerCruiser water-pump pulley for selected GM-based petrol marine engines equipped with a serpentine accessory belt and power steering.

The pulley mounts to the engine circulating-water pump and transfers crankshaft rotation through the serpentine belt to circulate coolant through the engine.

⚙️ Key Features

• Genuine used MerCruiser OEM water-pump pulley
• Correct current part number 863404T
• Supersedes earlier pulley 863404
• Serpentine-belt pulley for power-steering engine packages
• Factory diameter and groove profile for correct pump speed

🚤 Compatibility

Commonly used on

• MerCruiser GM V6 and small-block V8 circulating-water pumps
• Serpentine accessory drives equipped with power steering

Typically suits

• Engine models:
• MerCruiser 4.3L V6 with power steering
• MerCruiser 4.3L MPI Alpha and Bravo
• MerCruiser 5.0L carburetted V8
• MerCruiser 5.0L MPI Alpha and Bravo
• MerCruiser 5.7L V8
• MerCruiser 350 MAG
• MerCruiser 350 MAG MPI
• MerCruiser 350 MAG Horizon
• MerCruiser 6.2L MPI
• MerCruiser 377 MAG MPI
• Engine accessory diagrams specifying pulley 863404 or 863404T
• Engine Type: MerCruiser GM V6 and small-block V8 petrol sterndrive / inboard
• Year Range: Approximately late 1990s through the 2000s
• System Type: Circulating-water pump and serpentine accessory drive

🔌 Function

The pulley drives the circulating-water pump at the designed speed so coolant moves through the cylinder block, heads, thermostat housing and heat exchanger or exhaust system.

⚠️ Common Signs of Failure

• Pulley is bent or runs out of true
• Serpentine belt repeatedly comes off
• Pulley grooves are damaged or worn
• Mounting holes are elongated
• Rust or corrosion weakens the pulley
• Water-pump bearing is overloaded by pulley misalignment

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 863404T → Supersedes 863404
• 863404 earlier OEM water-pump pulley reference

OEM / Related Numbers

• 863404T
• 863404
• 863404-1
• 745061568754
• 862083 related idler assembly
• 807757T related idler pulley

Aftermarket / Verified Equivalents

• No aftermarket equivalent

📦 Condition

• Genuine used part
• Removed from running engine where applicable
• In good working condition unless otherwise stated