Michigan Motorsports Front LS Crankshaft Damper Seal — OE-fit for Gen III & IV LS (12585673) stops oil leaks

The Michigan Motorsports Front LS Crankshaft Damper Seal is an OE-spec replacement seal that stops front-crankshaft oil leaks on Gen III and Gen IV LS engines (fits GM 12585673 applications).

When an LS engine develops an oil drip from the front crank area, the front damper seal is often the culprit. This Michigan Motorsports unit is manufactured to match factory dimensions and materials so it installs cleanly around the crank snout and harmonic balancer. It’s intended for rebuilds, routine maintenance, and performance projects that require dependable oil control without modifying the engine’s front cover or balancer.

How does this seal restore oil control on my LS engine?

The seal replaces worn or hardened lip material that allows oil to escape at the crankshaft. By providing a fresh elastomer sealing lip and proper inner diameter tolerance, it re-establishes the barrier between the crankcase oil and the external accessory area. You’ll see reduced seepage and cleaner engine bays when installed correctly.

• Precisely sized to match GM part 12585673 fit and mounting geometry
• Elastomer compound resists heat and oil breakdown
• Tight lip profile minimizes capillary seepage at startup and under load

Which LS engines and models is this compatible with?

This front crankshaft damper seal is engineered for a broad span of Gen III and Gen IV LS-family engines. It fits common displacements used in GM trucks, SUVs, and performance cars, making it a versatile replacement when the original seal has failed. Confirm compatibility by cross-referencing GM 12585673 with your engine code or vehicle application.

• Fits 4.8L, 5.3L, 5.7L, 6.0L, 6.2L and 7.0L LS platforms
• Common applications: LS1, LS3, LQ4, LQ9, LS7 and other Gen III/IV variants
• Suitable for both factory and many aftermarket dampers/harmonic balancers

Is installation difficult and what should I prepare?

Installation is straightforward for anyone comfortable with basic engine front-end work. The seal requires careful seating and correct alignment to the crank snout; using the proper driver tool or installer reduces the risk of lip damage. Replace the seal during front cover or balancer service to avoid later removal and rework.

• Recommend removing harmonic balancer and cleaning crank snout before fitting
• Use a seal driver or socket sized to the outer diameter to press evenly
• Lightly oil sealing lip with engine oil to ease installation and prevent dry starts

What performance and durability can I expect?

Built from materials chosen to tolerate high under-hood temperatures and continuous oil exposure, this seal is intended to provide long-term service in both daily-driven and performance LS engines. While it doesn’t change oil system pressures or engine internals, it restores factory-level sealing performance and prevents progressive oil contamination of belts, pulleys, and accessory components.

• OE-quality materials resist heat, oil, and ambient contaminants
• Designed for long service life under normal operating conditions
• Helps maintain clean accessory drive components and under-hood appearance

Who is this for: owners and mechanics working on Gen III/IV LS engines who need a precise, OE-style replacement for a leaking front crankshaft damper seal. It’s ideal for restoration projects, routine maintenance, or performance builds where a reliable seal is required to prevent front-end oil leaks without altering the engine’s original configuration.