National 714679 Automatic Transmission Output Shaft Seal - Left

Overview of National 714679 Automatic Transmission Output Shaft Seal

The National 714679 automatic transmission output shaft seal is engineered for reliable sealing performance in select GM vehicles. Designed with precision dimensions and durable polyacrylate material, this oil seal helps maintain transmission fluid integrity in Buick, Cadillac, Oldsmobile, and Pontiac models.

• Inside diameter: 1.605 inches (40.770 mm)
• Outside diameter: 2.565 inches (65.150 mm)
• Thickness: 0.369 inches (9.373 mm)
• Bi-directional lip design for effective sealing
• Constructed from polyacrylate material for durability
• Redicoat surface treatment for enhanced wear resistance
• Overall width with side lip: 0.693 inches (17.600 mm)
• Compatible housing bore: 2.560 inches (65.020 mm)

Detailed Product Description and Specifications

The National 714679 is an automatic transmission output shaft seal designed to fit a range of GM vehicles including Buick Allante, Cadillac DeVille, DTS, Eldorado, Seville, Oldsmobile Aurora, Pontiac Bonneville, and Lucerne. This seal features a bi-directional lip design that provides effective sealing against transmission fluid leaks in both rotational directions. The polyacrylate material offers resistance to heat and wear, ensuring long service life under demanding transmission conditions. The Redicoat treatment further enhances the seal’s durability by reducing friction and wear on the sealing lip.

Applications and Common Issues Addressed

• Prevents transmission fluid leaks from the output shaft area
• Reduces contamination ingress into the transmission system
• Maintains proper fluid pressure for smooth transmission operation
• Helps avoid premature transmission wear caused by fluid loss
• Addresses seal degradation due to heat and mechanical stress

Installation Notes and Tips

• Ensure the housing bore is clean and free of debris before installation
• Verify the shaft diameter matches the 1.605 inch specification for proper fit
• Use appropriate tools to avoid damaging the seal during installation
• Apply a light coat of transmission fluid to the seal lip before fitting
• Check for proper seating and alignment to prevent leaks

Quality Assurance and Warranty Information

National transmission seals are manufactured to meet OEM specifications for fit and function. The 714679 seal undergoes rigorous quality control to ensure dimensional accuracy and material integrity. This part is part of the National 714000 series, known for consistent performance in automatic transmission sealing applications. Warranty coverage details should be confirmed with the original equipment manufacturer or distributor.