SUMO Billet Half Moon Seals (Cylinder Head Plugs) – Subaru EJ Engines

SUMO Billet Half Moon Seal Kit (Cylinder Head Plugs) – Subaru EJ Engines

Permanent Fix • Dual Pin Removal Tool • CNC Machined

Factory Subaru half moon seals (also called cylinder head plugs) are known to harden, crack, or even blow out over time — especially under high crankcase pressure. The SUMO Billet Half Moon Seal Kit eliminates these issues with a permanent upgrade, precision-machined from aircraft-grade 6061-T6 aluminum.

Unlike OEM plastic or rubber plugs that become brittle with heat cycles, SUMO half moons fit precisely and will not wear, warp, or deteriorate. Each kit includes a dual pin removal system and our custom tool, allowing you to service half moons without damaging or marking the cylinder head surface. The tool applies a controlled shear force that breaks the sealant cleanly, making removal quick and simple.

We recommend replacing valve cover gaskets at the same time as half moon service to ensure a leak-free install.

Key Features:

• Permanent Upgrade – Replaces OEM half moons (Subaru p/n 11051AA070) that are prone to leaking or failure

• CNC Machined – Cut from aircraft-grade 6061-T6 aluminum for strength and precision

• Dual Pin Removal System – Prevents damage when removing 

• Includes Removal Tool – Cleanly breaks sealant bond with controlled shear force

• Complete Kit – Sold as a set of 4 billet half moons + removal tool

• Durable Finish – Anodized for long-lasting protection

Vehicle Compatibility:

• Subaru Baja XT: 2004–2006

• Subaru Forester NA: 1998

• Subaru Forester XT: 2004–2007

• Subaru Impreza 2.5 NA: 1998

• Subaru Legacy GT: 1996–1999

• Subaru Legacy 2.5L GT: 2005–2009

• Subaru Outback XT: 2005–2007

• Subaru Legacy 3.0L: 2001–2007

• Subaru Outback 3.0L: 2001–2007

• Subaru SVX: 1995–1997

• Subaru WRX STI: 2004–2007

• Subaru WRX: 2002–2007

⚙️ Note: Always replace valve cover gaskets when servicing half moon seals.