FAG SS3878 Engine Crankshaft Seal - Rear

Engine Crankshaft Seal for Rear Applications

FAG SS3878 is an engine crankshaft seal built with a Viton sealing material and a rubber spring design with an auxiliary lip. It is specified for rear applications across a wide range of Buick, Chevrolet, Oldsmobile, and Pontiac vehicles, including rear crankshaft seal service on the Buick LeSabre, Chevrolet Impala, and Pontiac Bonneville.

Key Features

• Part number: SS3878
• Seal type: rubber, spring, auxiliary lip
• Sealing material: Viton
• Bore diameter: 3.92 in. / 99.568 mm
• Seal outside diameter: 3.928 in. / 99.771 mm
• Seal width: 12.7 mm / 3.228 in.
• Rear-position seal for listed vehicle applications
• Cross-reference part numbers include National 320691 and 32289

Detailed Description

Built for rear crankshaft sealing service, FAG SS3878 uses Viton for sealing performance and a spring-loaded rubber construction with an auxiliary lip to help maintain contact at the sealing surface. The dimensional specifications are important for proper fitment, with a 3.92-inch bore diameter, 3.928-inch outside diameter, and 12.7 mm width. This part number is listed for many GM rear applications, including Buick Allure, Buick LaCrosse, Buick Lucerne, Chevrolet Monte Carlo, and Pontiac Grand Prix. If you are replacing a rear engine crankshaft seal on a Buick LeSabre, Chevrolet Impala, or Pontiac Bonneville, SS3878 is the cataloged match for those vehicles.

What This Seal Helps Address

• Oil leakage at the rear crankshaft sealing area
• Contamination entering the seal area from dirt, dust, or moisture
• Grease or lubricant loss around the bearing/seal interface
• Wear-related sealing issues on high-mileage rear engine service
• Replacement needs during engine reseal or transmission-related service

Installation Notes and Tips

Verify the bore diameter, outside diameter, width, and rear position before installation. Clean the sealing surface thoroughly and inspect the crankshaft and housing for wear, scoring, or contamination that could affect seal life. Confirm vehicle-specific fitment by year, make, model, and rear position before ordering. Fits 2005-2009 Buick Allure, Rear; Fits 2005-2009 Buick LaCrosse, Rear; Fits 2006-2008 Buick Lucerne, Rear; Fits 2004-2008 Pontiac Grand Prix, Rear; Fits 2000-2005 Chevrolet Impala, Rear; Fits 1998-2005 Chevrolet Monte Carlo, Rear; Fits 1987-2005 Pontiac Bonneville, Rear; Fits 1991-2005 Buick LeSabre, Rear; Fits 1991-2005 Buick Park Avenue, Rear; Fits 1997-2004 Buick Regal, Rear; Fits 1995-2002 Chevrolet Camaro, Rear; Fits 1992-1999 Oldsmobile 88, Rear; Fits 1991-1996 Oldsmobile 98, Rear; Fits 1992-1995 Chevrolet Lumina APV, Rear; Fits 1992-1995 Oldsmobile Silhouette, Rear; Fits 1991-1993 Buick Riviera, Rear; Fits 1995-1999 Buick Riviera, Rear; Fits 1998-1999 Chevrolet Lumina, Rear; Fits 1998-1999 Oldsmobile Intrigue, Rear; Fits 1996-1999 Oldsmobile LSS, Rear; Fits 1997-1998 Oldsmobile Regency, Rear; Fits 1991-1992 Oldsmobile Toronado, Rear; Fits 1992 Pontiac Grand Am, Rear; Fits 1992 Pontiac Trans Sport, Rear; Fits 1991 Buick Century, Rear; Fits 1991 Buick Reatta, Rear; Fits 1991 Buick Skylark, Rear; Fits 1991 Oldsmobile Cutlass Calais, Rear; Fits 1991 Oldsmobile Cutlass Ciera, Rear; Fits 1991 Oldsmobile Delta 88, Rear.

Quality Assurance

FAG designs seals to meet vehicle manufacturer specifications and works with suppliers to build to FAG quality standards. The brand’s sealing focus centers on controlling contamination and helping preserve lubricant at the bearing interface over the service life of the component.