National 5278 Engine Crankshaft Seal - Rear

Overview of National Engine Crankshaft Seal 5278

The National 5278 engine crankshaft seal is designed to provide reliable sealing performance for various Ford and Mercury vehicles. Engineered with durable PTFE material, this oil seal kit ensures effective protection against oil leaks and contamination in your engine's crankshaft area.

• Inside diameter: 3.750 inches (95.250 mm)
• Outside diameter: 4.506 inches (114.450 mm)
• Thickness/width: 0.362 inches (9.190 mm)
• Material: PTFE for enhanced durability and chemical resistance
• Type: Fw-h oil seal kit

Detailed Product Description

The National 5278 crankshaft seal is manufactured with precision to fit specific Ford and Mercury models, including the Bronco, E-100 Econoline series, E-150, E-250, E-350 Econoline variants, F-100, F-150, F-250, F-250 HD, F-350, Grand Marquis, LTD, LTD Crown Victoria, and Mustang. Its PTFE construction offers excellent resistance to heat, oil, and wear, making it suitable for demanding engine environments. The seal’s dimensions—3.750 inch inside diameter and 4.506 inch outside diameter—ensure a secure fit on the crankshaft, while the 0.362 inch thickness provides a reliable barrier against oil leakage.

Common Applications and Problem Solving

• Prevents oil leaks around the crankshaft in Ford Bronco and Mustang engines
• Reduces contamination ingress in E-100 and E-150 Econoline models
• Maintains engine oil pressure by sealing crankshaft openings in F-150 and F-250 trucks
• Helps avoid premature engine wear caused by oil loss in Mercury Grand Marquis and LTD vehicles
• Supports engine longevity by maintaining proper sealing in E-250 and E-350 Econoline Club Wagon models

Installation Notes and Tips

• Ensure the crankshaft surface is clean and free of debris before installation
• Use appropriate tools to press the seal evenly without damaging the PTFE material
• Verify the seal orientation matches the engine specifications for proper oil retention
• Check for any signs of wear or damage on the crankshaft before installing the new seal
• Consult vehicle service manuals for torque and installation procedures specific to Ford and Mercury models

Quality Assurance and Warranty

National engine crankshaft seals are manufactured to meet industry standards for durability and performance. The PTFE material used in part number 5278 offers chemical and temperature resistance suitable for automotive engine environments. While specific warranty details may vary, National products typically come with a limited warranty against manufacturing defects, ensuring confidence in the product’s reliability when installed correctly.