The Enginetech S4686 is a 1-piece viton rear main seal engineered as a stock replacement for 1981-2019 Ford, Lincoln, Mazda, Mercury and more engine applications.
Important Notes
- 1-Piece design: verify your engine uses a 1-piece seal before ordering - 1-piece and 2-piece seals are not interchangeable.
- Viton construction: fluoroelastomer compound for high-temperature, long-cycle sealing performance.
- Offset Lip configuration.
- From 9/29/81.
- From 1/2/83.
- From 11/31/82.
- From 09/29/81.
Specifications
| Brand | Enginetech |
| Part Number | S4686 |
| Product Type | Rear Main Seal |
| Design | 1-Piece |
| Material | Viton |
| Lip Configuration | Offset Lip |
| Country of Origin | Taiwan |
Vehicle Fitment
- Years: 1981-2019
- Makes: Ford, Lincoln, Mazda, Mercury, Merkur
- Models: 6, Aerostar, Aviator, B2300, B2500, Blackwood, Bronco, Capri, Colony Park, Continental, Contour, Cougar, Country Squire, Courier, Crown Victoria, E-100 Econoline, E-100 Econoline Club Wagon, E-150, E-150 Club Wagon, E-150 Econoline, E-150 Econoline Club Wagon, E-250, E-250 Econoline, E-350 Club Wagon, E-350 Econoline, and more
The rear main seal (also called the crankshaft rear seal) prevents engine oil from leaking between the back of the crankshaft and the transmission bell housing. Over miles and heat cycles, the seal hardens, cracks, or takes a permanent compression set - producing the characteristic oil drip at the bell housing and, if left unchecked, oil contamination of the clutch disc or flex plate. Replacing the rear main seal during a transmission service or engine rebuild restores the final oil seal between the crankshaft and drivetrain, preventing slow leaks and protecting the clutch and flywheel from contamination.
