The Enginetech S4891 is a 1-piece viton rear main seal engineered as a stock replacement for 1992-2004 AM General, Chevrolet, GMC, Hummer 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.
- Double Lip configuration.
Specifications
| Brand | Enginetech |
| Part Number | S4891 |
| Product Type | Rear Main Seal |
| Design | 1-Piece |
| Material | Viton |
| Lip Configuration | Double Lip |
| Country of Origin | Taiwan |
| OEM / Aftermarket Cross References | FEL-PRO:BS40604, Victor Reinz:JV1617 |
Vehicle Fitment
- Years: 1992-2004
- Makes: AM General, Chevrolet, GMC, Hummer
- Models: B7, Blazer, C1500, C1500 Suburban, C2500, C2500 Suburban, C3500, C3500HD, Express 2500, Express 3500, G20, G2500, G30, G3500, H1, Hummer, K1500, K1500 Suburban, K2500, K2500 Suburban, K3500, P30, P3500, Savana 2500, Savana 3500, 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.
