National 231004 Engine Crankshaft Seal - Rear

National 231004 Rear Engine Crankshaft Seal

National 231004 is a rear engine crankshaft oil seal built for precise sealing in a wide range of applications, including Jaguar, Land Rover, Aston Martin, Ford Thunderbird, Lincoln LS, and Toyota Land Cruiser models. It uses a silicone sealing material and metric dimensions to match the housing and shaft requirements of the listed vehicles.

Key Features

• Rear engine crankshaft seal for oil control at the back of the crankshaft
• Silicone material for sealing performance in demanding engine environments
• Metric dimensions: 100.000 mm shaft diameter, 120.000 mm housing bore, 11.000 mm width
• Outside diameter: 120.120 mm; inside diameter: 100.000 mm
• National 231004 is part of the 230000 series
• Direct replacement style for rear seal service on select V8 and inline applications

Detailed Description

National 231004 is an engine crankshaft seal designed for the rear position, where it helps maintain proper oil containment between the crankshaft and engine housing. The seal measures 3.937 inches inside diameter, 4.735 inches outside diameter, and 0.433 inches in width, with a 4.724-inch housing bore specification. Its silicone construction supports consistent sealing performance across the listed fitments. This part cross-references Bosch 17226 and Four Seasons 39125 for the same application. National 231004 is a practical choice for rear main seal service on vehicles such as the 2004-2009 Jaguar XJ8, 2006-2009 Land Rover Range Rover, and 2002-2005 Ford Thunderbird.

What It Helps Address

• Rear engine oil leakage at the crankshaft seal area
• Oil seepage that can leave residue on the transmission bellhousing or engine underside
• Loss of crankcase oil caused by worn sealing surfaces
• Seal deterioration from age, heat, and engine contamination
• Service replacement needs during rear main seal repair

Installation Notes and Tips

Confirm the shaft diameter, housing bore, and seal width before installation to match the engine specification. Inspect the crankshaft sealing surface for wear, scoring, or contamination before fitting the new seal. Clean the housing thoroughly and install the seal squarely to avoid distortion. Verify rear-position fitment for the exact vehicle application, including 2006-2017 Aston Martin V8 Vantage, 2009-2010 Jaguar XF, and 2006-2009 Land Rover Range Rover Sport.

Quality Assurance

National has supplied sealing solutions for more than 75 years and continues to develop engine sealing components for modern vehicle applications. National 231004 reflects that experience with a metric, silicone rear crankshaft seal design for select Jaguar, Land Rover, Aston Martin, Ford, Lincoln, and Toyota applications.