GJYSYP Oil Valley Seal Plugs for Gen IV/Gen V LSX LT Engines — 8‑pc Press‑Fit Removable 4.8–6.2L

These GJYSYP 8-piece oil valley seal plugs close the AFM/DOD oil passages in genuine GM valley covers so you can convert to a conventional lifter setup without oil seepage.

If you’re swapping out AFM/DOD components or converting a variable-displacement valley to a traditional lifter system on GM Gen IV and Gen V engines, leaking or open AFM oil passages are a common issue. These press-fit plugs are made to seal the oil holes in genuine DOD/AFM valley covers on 2005–2019 Chevrolet, GM, Oldsmobile and Cadillac engines (4.8L, 5.3L, 6.0L, 6.2L displacements). They provide a neat, removable seal that prevents oil from entering the AFM tappet area once the AFM hardware is removed.

Which engines and valley covers are these plugs compatible with?

These plugs are specified for use with original equipment DOD/AFM valley covers found on many 4th- and 5th-generation GM small-block engines from 2005–2019. They are not universal — fitment is limited to genuine DOD/AFM valley covers and will not seat correctly in non-OEM or aftermarket covers.

• Compatible series: Gen IV and Gen V LSX and LT engines (L99, L83, L86, LT1, LT4, LT5).
• Typical displacements: 4.8L, 5.3L, 6.0L, 6.2L.
• Years: 2005–2018 for many Gen IV; 2014–2019 for 5th-generation variants.
• Only for genuine DOD/AFM valley covers — not for aftermarket or non-DOD covers.

How are the plugs installed and removed?

Installation is straightforward: each plug is gently tapped into the oil passage until it sits flush with the bottom edge of the valley cover. A 4 mm x 0.7 threaded recess in the top permits later removal with a matching bolt if you need to retrieve the plug or access the passage again.

• Install by lightly tapping until flush with the oil hole lip.
• Top has a 4 mm x 0.7 threaded hole for extraction using a bolt.
• If fit is tight, pre-freezing the plugs for one hour can help ease installation.
• Designed for a snug, oil-tight fit — avoid hammering excessively.

Will these plugs work when converting AFM/DOD to a conventional lifter system?

Yes — they are commonly used when converting AFM/DOD-equipped engines to a traditional valve train. By sealing the AFM oil galleries beneath the VLOM plate, the plugs prevent oil from feeding removed AFM components and help maintain normal oil routing for a conventional lifter setup.

• Prevents oil flow into stock AFM tappets after AFM removal.
• Maintains oil integrity for non-AFM valve train operation.
• Removable design supports serviceability or reversion to stock later.

Are there special precautions or installation tips I should know?

These plugs are engineered for a tight press fit; they must be used only with genuine DOD/AFM valley covers. Avoid forcing them into aftermarket or modified covers, and use light, controlled taps during seating. If you experience small gaps, try pre-freezing the plugs for about an hour to improve fitment.

• Do not use with non-genuine or aftermarket valley covers.
• Seat gently and check flush alignment at the bottom edge.
• Use the threaded top for easy removal instead of prying the plug out.
• Contact GJYSYP support for quality or warranty questions.

Who this product is for: technicians, engine builders, and DIY enthusiasts who are converting GM AFM/DOD valve trains to conventional setups or sealing OEM AFM oil passages. If you have a genuine DOD/AFM valley cover on a Gen IV or Gen V small-block and need a reliable, removable oil passage seal, this 8-piece GJYSYP kit provides a purpose-built solution — just confirm your cover is OEM before ordering.