1. Technical Specifications

2. Key Features

• Fiber-Reinforced Nylon Construction: Impervious to galvanic and saltwater corrosion, preventing electrochemical corrosion, scaling, or seizing issues common with metal bases.

• Dual Tangential Anti-Rotation Ribs: Molded locating guide ribs lock securely into the gearcase cavity slots, preventing rotational displacement under high hydraulic torque and assisting water intake routing.

• Precision Oil Seal Bore: Stepped concentric internal cavity provides accurate press-fit retention for driveshaft oil seals, ensuring even lip contact and zero fluid bypass.

• Direct OEM Fitment: Manufactured strictly to factory dimensional standards, ensuring seamless drop-in installation with precise outer O-ring groove alignment.

3. Compatible Models

Primarily compatible with Yamaha 4-stroke mid-range (30HP – 70HP) outboard lower unit cooling systems:

• Yamaha F30 Series: F30B, F30LA EFI 4-stroke models

• Yamaha F40 Series: F40D, F40F, F40LA 4-stroke models

• Yamaha F50 / T50 Series: F50F, F50H, T50LB standard & high-thrust models

• Yamaha F60 / T60 Series: F60C, F60F, T60LB 4-stroke models

• Yamaha F70 Series: F70A, F70LA 16-valve 4-stroke models

4. Aftermarket & Brand Compatibility

• OEM Brand Fitment:

• Yamaha Marine: Engineered for Yamaha 30HP to 70HP 4-stroke outboard lower unit water pump and gearcase sealing assemblies.

• PREMARINE Brand Aftermarket Replacement:

• PREMARINE Quality Standard: PREMARINE specializes in high-reliability marine cooling and drivetrain sealing components. This nylon water pump base is engineered using high-impact, hydrolysis-resistant engineering polymers.

• Direct OEM-Level Performance: Tensile strength, thermal stability, and dimensional tolerances meet or exceed OEM specifications, offering robust protection against gear oil emulsification and casing distortion for professional marine workshops.

5. Common Symptoms & Troubleshooting

• Gearcase Oil Emulsification (Milky / Contaminated Gear Lube):

• Cause: Worn or loose oil seal pocket inside the nylon housing, or a hairline crack allowing high-pressure cooling water past the seals into the gearcase.

• Troubleshooting: Drain gearcase lube to inspect for water intrusion. If emulsified, remove the water pump assembly and replace the nylon base along with new driveshaft oil seals.

• Reduced Water Pump Pressure / Low Pee Stream at Idle:

• Cause: Degraded outer O-ring or warped top mounting face on the nylon base breaking the suction seal beneath the stainless wear plate.

• Troubleshooting: Inspect the upper face of the nylon base for flatness and groove wear; replace if warped or grooved.

• Broken Locating Ribs Causing Vibration or Misalignment:

• Cause: Excessive force during prior assembly or foreign debris impact breaking the side anti-rotation ribs.

• Troubleshooting: Inspect the integrity of the side ribs; ensure both ribs engage properly with the gearcase guide slots upon installation.

OEM Part Numbers

Compatible OEM references include:

6BG-44341-00

6BG-44341-00-00

6BG-44341

Compatible Engine Models

This Water Pump Lower Housing is primarily designed for:

4-Stroke 30/40/50/60/70HP

If you are unsure about compatibility, please provide your engine model number or identification plate for verification before ordering.

Applications

This Water Pump Lower Housing is commonly used for:

Outboard engine repair

Engine rebuilding projects

Marine maintenance workshops

Boat fleet maintenance

Commercial fishing vessels

Recreational boats

Marine spare parts distribution