LS Steam Port Block‑Off Plates – Coolant Crossover Delete Kit (LS1/LS2/LS3/LS6, LQ4/LQ9, L92/L99, LM7/L33/LR4) 1997–2014

LS Cylinder Head Steam Port Block-Off Plates

Simplify your coolant crossover plumbing by sealing the front or rear steam vent ports on LS cylinder heads. This kit blocks one pair of ports (left + right), helping clean up routing on swaps and custom builds while maintaining a tidy engine bay.

Key Features

• Blocks one pair of LS steam/coolant crossover ports (front or rear)
• Direct fit for Gen III/IV LS-based engines, 1997–2014
• Lightweight aluminum plates with O-ring seals
• Includes hardware for a quick, hassle-free install

Compatibility

Works with common LS platforms, including (not limited to):

• LSX family: LS1, LS2, LS3, LS6
• Truck variants: LQ4, LQ9, L92, L99, LM7, L33, LR4
• Model years: 1997–2014

What’s Included

• (2) Coolant/steam port block-off plates (left & right)
• (2) O-rings
• (2) Bolts

Specifications

Installation Notes

• Can be installed on the front or rear of the cylinder heads.
• Use a clean sealing surface; lightly oil O-rings before installation.
• Tighten bolts to OEM-equivalent spec for the thread size (do not overtighten).
• Important: LS engines require at least one functional steam vent path to purge trapped air. Ensure your cooling system still provides a proper bleed/vent route (e.g., to the water pump, radiator, or a crossover) to prevent hot spots.

Use Case

Ideal for swaps and custom builds where simplifying or relocating steam crossover lines is desired while sealing unused ports cleanly and securely.