GJYSYP Oil Valley Seal Plugs for GM Gen IV/V LSX & LT Engines — 8‑pc OE-fit with removable threaded tops

GJYSYP Oil Valley Seal Plugs are an 8-piece kit designed to seal AFM/DOD oil passages in genuine GM DOD/AFM valley covers for 2005–2019 Gen IV and Gen V LSX and LT engines.

This kit provides OE-compatible plugs that block the AFM/DOD oil passages when converting to a non-active lifter setup or replacing AFM components with conventional lifters. The plugs are sized and shaped to fit genuine GM valley covers only — they will not seat correctly in aftermarket or non-genuine DOD/AFM covers. Each plug installs by gently tapping it flush into the oil hole and includes a small removable threaded top for future extraction.

Will these plugs fit my engine and valley cover?

These plugs are made for GM 4th- and 5th-generation AFM/DOD valley covers used on many 2005–2019 LSX and LT applications. They suit L99, L83, L86, LT1, LT4, LT5 and similar blocks in 4.8L, 5.3L, 6.0L and 6.2L displacements — only when the valley cover is a genuine DOD/AFM unit.

• Compatible with genuine GM DOD/AFM valley covers from 2005–2019.
• Intended for Gen IV and Gen V engines (LSX and LT families).
• Not compatible with aftermarket or non-genuine valley covers.
• Check valley cover casting and oil hole pattern before ordering.

How are the plugs installed and removed?

Installation is simple: each plug is tapped gently into the oil passage until its bottom edge sits flush with the valley cover surface. For removal, the plug has a 4 mm x 0.7 threaded hole in the top so a small extractor or bolt can back the plug out without damaging the cover.

• Tap each plug in gently until flush with the cover underside.
• Use the 4 mm x 0.7 thread for safe removal if needed.
• If fit feels loose, temporarily freeze plugs before installation for a tighter seal.
• Do not force-fit into aftermarket valley covers — they will not seat correctly.

What purpose do these plugs serve during AFM to conventional lifter conversions?

When converting AFM/DOD systems to a fixed lifter arrangement, the original oil passages that supply AFM components must be sealed to prevent oil routing to inactive tappets. These plugs close those passages at the valley cover, preventing unwanted oil flow into removed or replaced AFM parts.

• Seals AFM/DOD oil passages under the VLOM plate to block oil flow.
• Helps maintain correct oil routing for non-AFM lifter setups.
• Prevents oil from filling unused AFM tappets after conversion.
• Provides a reversible solution thanks to the removable top thread.

Are there any installation tips or warranty details I should know?

The plugs are engineered as a tight-fit installation; if a plug will not seat properly, freezing it for about an hour can shrink the material for easier insertion. GJYSYP inspects every kit and offers after-sales support and warranty service for peace of mind.

• Tight-fit design — freeze briefly for easier seating if needed.
• Do not use with non-stock or aftermarket valley covers.
• GJYSYP provides quality inspection and warranty support.
• Contact seller support for fit questions prior to installation.

Who is this for: This 8-piece GJYSYP kit is for professional mechanics, DIY engine builders and performance enthusiasts converting AFM/DOD systems to traditional lifter configurations on compatible GM Gen IV and Gen V engines. If you have a genuine GM DOD/AFM valley cover and need a clean, reversible way to block AFM oil passages, this kit is designed for that purpose. Do not purchase if your vehicle uses an aftermarket or non-genuine valley cover — this product will not fit those designs.