National 4918 Automatic Transmission Torque Converter Seal - Front

Automatic Transmission Torque Converter Seal

National 4918 is an automatic transmission torque converter seal built for front-position applications across a wide range of GM, Buick, Pontiac, Saturn, Volvo, and Chevrolet vehicles. It uses a polyacrylate sealing material with a clockwise-spiral lip design to help maintain a consistent seal at the torque converter interface.

National has supplied premium sealing solutions for more than 75 years, and this seal reflects that focus on dimensional accuracy and modern transmission service needs. Part number 4918 is also identified by the cross-reference 24204772 for the same application.

Key Features

• Automatic transmission torque converter seal for front applications
• Polyacrylate sealing material for transmission fluid sealing performance
• Clockwise-spiral lip design
• Redicoat finish for installation support
• Series 4000, Type 83
• Inside diameter: 1.787 in. / 45.390 mm
• Outside diameter: 3.238 in. / 82.250 mm
• Flanged outside diameter: 3.450 in. / 87.630 mm
• Width: 0.335 in. / 8.510 mm
• Housing bore: 3.228 in. / 82.000 mm

Detailed Description

National 4918 is an oil seal specified for automatic transmission torque converter service where the seal must retain fluid and support stable operation under rotating shaft conditions. The polyacrylate material and spiral lip profile are selected for transmission environments, while the listed dimensions help confirm proper housing and shaft fit before installation. This part number 4918 is used on front-position applications for vehicles such as the 2006 Buick Allure, 2006 Chevrolet Impala, and 2006 Pontiac Grand Prix, along with many earlier Buick, Pontiac, Oldsmobile, Saturn, Volvo, and Chevrolet models.

Vehicle Fitment

• Fits 2006 Buick Allure, Front
• Fits 2006 Buick LaCrosse, Front
• Fits 2006 Buick Lucerne, Front
• Fits 2006 Buick Rendezvous, Front
• Fits 2006 Buick Terraza, Front
• Fits 2006 Chevrolet Impala, Front
• Fits 2006 Chevrolet Malibu, Front
• Fits 2006 Chevrolet Monte Carlo, Front
• Fits 2006 Chevrolet Uplander, Front
• Fits 2006 Pontiac G6, Front
• Fits 2006 Pontiac Grand Prix, Front
• Fits 2006 Pontiac Montana, Front
• Fits 2006 Saturn Relay, Front
• Fits 2006 Volvo S80, Front
• Fits 2006 Volvo XC90, Front
• Fits 2005 Buick Allure, N/A
• Fits 2000-2005 Buick Century, N/A
• Fits 2005 Buick LaCrosse, N/A
• Fits 2000-2005 Buick LeSabre, N/A
• Fits 1997-2005 Buick Park Avenue, N/A
• Fits 2002-2005 Buick Rendezvous, N/A
• Fits 2005 Buick Terraza, N/A
• Fits 2004-2005 Chevrolet Impala, N/A
• Fits 2000-2005 Chevrolet Impala, N/A
• Fits 2004-2005 Chevrolet Monte Carlo, N/A
• Fits 2000-2005 Chevrolet Monte Carlo, N/A
• Fits 2005 Chevrolet Uplander, N/A
• Fits 2001-2005 Pontiac Aztek, N/A
• Fits 2000-2005 Pontiac Bonneville, N/A
• Fits 1997-2005 Pontiac Grand Prix, N/A
• Fits 2000-2005 Pontiac Grand Prix, N/A
• Fits 2000-2005 Pontiac Montana, N/A
• Fits 2005 Saturn Relay, N/A
• Fits 1999-2005 Volvo S80, N/A
• Fits 2003-2005 Volvo XC90, N/A
• Fits 1997-2004 Buick Regal, N/A
• Fits 2000-2004 Oldsmobile Silhouette, N/A
• Fits 1999-2004 Volvo S80, N/A
• Fits 2001-2003 Oldsmobile Aurora, N/A
• Fits 1997-2003 Pontiac Bonneville, N/A
• Fits 2000-2002 Oldsmobile Intrigue, N/A
• Fits 2000-2001 Chevrolet Lumina, N/A
• Fits 1998-1999 Buick LeSabre, N/A
• Fits 1997-1999 Buick Park Avenue, N/A
• Fits 1998-1999 Buick Regal, N/A
• Fits 1997-1999 Buick Riviera, N/A
• Fits 1998-1999 Chevrolet Lumina, N/A
• Fits 1998-1999 Chevrolet Monte Carlo, N/A
• Fits 1997-1999 Oldsmobile 88, N/A
• Fits 1998-1999 Oldsmobile Intrigue, N/A
• Fits 1997-1999 Oldsmobile LSS, N/A
• Fits 1999 Oldsmobile Silhouette, N/A
• Fits 1997-1999 Pontiac Bonneville, N/A
• Fits 1997-1999 Pontiac Grand Prix, N/A
• Fits 1999 Pontiac Montana, N/A
• Fits 1999 Pontiac Trans Sport, N/A
• Fits 1997-1998 Oldsmobile Regency, N/A

Common Service Uses

• Replacing a leaking torque converter seal during transmission service
• Addressing automatic transmission fluid seepage at the front seal area
• Restoring sealing performance after transmission teardown or overhaul
• Correcting wear-related leakage around the converter shaft interface
• Supporting proper sealing on 4T65-E, 4T65-E-HD, and related applications noted in fitment

Installation Notes and Tips

Verify shaft, housing bore, and seal dimensions before installation. The listed 1.787 in. shaft size, 3.228 in. housing bore, and 0.335 in. width should be checked against the transmission case and converter area to confirm proper seating. Clean the sealing surface thoroughly, inspect for scoring or wear, and follow the service procedure for the specific transmission family before returning the vehicle to service.

Quality Assurance

National has more than 75 years of experience in sealing products, and this torque converter seal is part of the brand’s 4000 series. The design uses a polyacrylate sealing material and Redicoat finish to support consistent fit and sealing performance in transmission service.