National 39803 Engine Crankshaft Seal - Front

Overview of National Engine Crankshaft Seal 39803

The National 39803 engine crankshaft seal is designed for reliable sealing performance in Dodge trucks including D250, D350, Ram 2500, Ram 3500, W250, and W350 models. Engineered with precision dimensions and durable PTFE material, this oil seal helps maintain engine integrity by preventing oil leaks around the crankshaft.

• Inside diameter: 2.500 inches (63.5 mm)
• Outside diameter: 3.135 inches (79.63 mm)
• Thickness/width: 0.315 inches (8.0 mm)
• Clockwise-spiral lip design (helix type)
• Material: PTFE for enhanced wear resistance
• Housing bore diameter: 3.130 inches (79.5 mm)
• Part number: 39803, Series 39000

Technical Details and Material Specifications

This National crankshaft seal (part number 39803) features a PTFE sealing lip with a clockwise-spiral helix design, which aids in directing oil back into the engine and reducing leakage. The seal’s precise inside diameter of 2.500 inches matches the shaft size of 63.5 mm, ensuring a tight fit on the crankshaft. The outside diameter of 3.135 inches fits securely within the housing bore of 3.130 inches, providing a stable seal interface. With a thickness of 0.315 inches, the seal maintains durability under engine operating conditions.

Compatible Vehicles and Applications

This engine crankshaft seal is compatible with various Dodge heavy-duty trucks, specifically the D250, D350, Ram 2500, Ram 3500, W250, and W350 models. It is designed to replace worn or damaged seals in these vehicles to prevent oil leaks and maintain engine performance.

• Prevents oil leaks around the crankshaft
• Reduces contamination ingress into the engine
• Maintains proper lubrication pressure
• Helps avoid engine damage caused by oil loss
• Replaces worn or damaged crankshaft seals

Installation Notes and Tips

When installing the National 39803 crankshaft seal, ensure the housing bore and shaft 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 clockwise-spiral lip design for optimal oil retention. Lubricate the seal lip lightly with clean engine oil before installation to reduce initial wear.

Quality Assurance and Warranty

National’s 39803 crankshaft seal is manufactured to meet industry standards for durability and sealing performance. Constructed from PTFE material, it offers resistance to heat, wear, and chemical exposure typical in engine environments. This part is backed by National’s quality control processes to ensure consistent fit and function. Warranty coverage details should be confirmed with the product documentation or distributor.