National 39805 Engine Crankshaft Seal - Rear

Overview of National 39805 Engine Crankshaft Seal

The National 39805 engine crankshaft seal is designed for reliable sealing performance in Dodge D250, D350, W250, and W350 models. Engineered with precision, this oil seal helps maintain engine integrity by preventing oil leaks around the crankshaft.

• Inside diameter: 130 mm (5.118 inches)
• Outside diameter: 150.44 mm (5.923 inches)
• Thickness/width: 14.8 mm (0.583 inches)
• Material: PTFE for enhanced durability and chemical resistance
• Helix type: Counter-clockwise spiral lip design for effective sealing
• Housing bore diameter: 150 mm (5.906 inches)
• Compatible with Dodge D250, D350, W250, and W350 models

Technical Details and Design Features

The National 39805 crankshaft seal features a PTFE (polytetrafluoroethylene) construction, which offers excellent resistance to heat, chemicals, and wear. Its counter-clockwise spiral lip design ensures a tight seal around the crankshaft, reducing the risk of oil leakage under various operating conditions. The seal’s dimensions—130 mm inside diameter and 150.44 mm outside diameter—are engineered to fit precisely within the housing bore of 150 mm, providing a secure fit for the specified Dodge truck models. The 14.8 mm thickness contributes to the seal’s structural integrity and longevity.

Compatible Vehicles and Applications

This engine crankshaft seal is specifically compatible with Dodge heavy-duty trucks, including the D250, D350, W250, and W350 series. It is designed to replace worn or damaged seals in these models, ensuring proper engine oil containment and preventing contamination.

• Prevents oil leaks around the crankshaft
• Reduces engine contamination from external debris
• Maintains engine oil pressure and efficiency
• Minimizes wear on crankshaft and related components
• Helps avoid costly engine repairs due to seal failure

Installation Notes and Tips

When installing the National 39805 crankshaft seal, ensure the housing bore and crankshaft surfaces are clean and free of debris. Use appropriate tools to press the seal evenly into the housing bore without damaging the sealing lip. Verify the seal orientation matches the counter-clockwise spiral lip design for optimal performance. Lubricate the seal lip lightly with engine oil before installation to reduce initial wear.

Quality Assurance and Warranty

National manufactures the 39805 crankshaft seal to meet industry standards for durability and performance. The use of PTFE material and precise engineering supports long service life under demanding conditions. While specific warranty details may vary, National typically offers coverage against manufacturing defects to ensure customer confidence in the product.