Genuine Nissan RB Rocker Cover Half Moon Seal – RB20 RB25 RB26 CA18 VG30 – 11051-58S00
Keep your Nissan engine properly sealed with the Genuine OEM Nissan Rocker Cover Half Moon Seal – 11051-58S00, a factory replacement rubber seal designed for compatible Nissan RB, CA18 and VG-series engines, including the legendary RB26DETT.
Also known as a cam cover half moon seal or rocker cover half moon gasket, this genuine Nissan component fits into the corresponding semicircular recess at the rear of the cylinder head, helping prevent engine oil from escaping around the rocker cover sealing area.
Over time, original half moon seals can harden, shrink or deteriorate due to repeated engine heat cycles and age. This may contribute to oil leaks around the rear of the cylinder head, particularly on older Nissan performance engines.
Manufactured to Nissan's original equipment specifications, this genuine replacement provides factory-style fitment and sealing performance for compatible applications.
Whether you're replacing the rocker cover gaskets on your RB25DET Skyline, rebuilding an RB26DETT GT-R engine or carrying out preventative maintenance, replacing ageing half moon seals is an important part of a thorough rocker cover reseal.
Important: This listing is for one (1) half moon seal only. Two (2) seals are required per engine for the applications covered by this listing. Please order a quantity of two when completing a full rocker cover reseal.
Product Details
- Brand: Genuine Nissan
- Part Number: 11051-58S00
- Product Type: Rocker Cover Half Moon Seal / Cam Cover Half Moon Gasket
- Installation Position: Rear Cylinder Head / Rocker Cover Sealing Area
- Material: OEM Rubber
- Quantity Supplied: 1 Half Moon Seal
- Quantity Required: 2 Per Engine for a Complete Reseal
- Condition: Brand New – Genuine Nissan OEM
Engine Compatibility
- Nissan RB20DE – Compatible applications
- Nissan RB20DET – Compatible applications
- Nissan RB25DE (Non-NEO) – Compatible applications
- Nissan RB25DET (Non-NEO) – Compatible applications
- Nissan RB26DETT – Compatible applications
- Nissan CA18DE – Selected applications
- Nissan CA18DET – Selected applications
- Nissan VG30DE – Selected applications
- Nissan VG30DETT – Selected applications
Important: Compatibility depends on the cylinder head and rocker cover design. RB25 NEO applications are not included in the confirmed fitment list. Please verify Nissan part number 11051-58S00 against your original component or factory parts catalogue before purchasing.
Vehicle Compatibility
- Nissan Skyline R31 – Selected compatible engine applications
- Nissan Skyline R32 – Selected compatible engine applications
- Nissan Skyline R33 – Selected compatible engine applications
- Nissan Skyline R34 – Selected compatible engine applications
- Nissan Skyline R32 GT-R (BNR32) – RB26DETT
- Nissan Skyline R33 GT-R (BCNR33) – RB26DETT
- Nissan Skyline R34 GT-R (BNR34) – RB26DETT
- Nissan Stagea WC34 – Selected RB-powered models
- Nissan Stagea 260RS – RB26DETT
- Nissan Laurel C33 / C34 – Selected compatible engine applications
- Nissan Cefiro A31 – Selected compatible engine applications
- Nissan Silvia S13 / 180SX – Selected CA18-powered models
- Nissan 300ZX / Fairlady Z (Z32) – Selected VG30-powered models
Please confirm compatibility using the original Nissan part number and engine configuration, particularly for modified or engine-swapped vehicles.
Key Features & Benefits
- Genuine Nissan OEM replacement half moon seal
- Manufactured from factory-specification rubber sealing material
- Helps prevent engine oil leaks from the rocker cover sealing area
- Designed for compatible Nissan RB, CA18 and VG-series engines
- Replaces hardened, brittle, compressed or deteriorated original seals
- Ideal for rocker cover gasket replacements
- Suitable for engine rebuilds and preventative maintenance
- Maintains factory-style fitment and sealing performance
- Excellent for Skyline GT-R and classic Nissan engine restorations
Why Replace Your Rocker Cover Half Moon Seals?
The rocker cover half moon seals form part of the sealing arrangement between the cylinder head and rocker cover on compatible Nissan engines.
After years of heat exposure and engine operation, the original rubber can lose flexibility and sealing effectiveness, allowing engine oil to escape around the rear of the cylinder head.
Common signs of deteriorated half moon seals include:
- Engine oil leaking from the rear of the rocker cover area
- Oil residue running down the back of the cylinder head
- Hardened, cracked or brittle original rubber seals
- Oil seepage after a rocker cover gasket replacement
- Visible deterioration when the rocker cover is removed
Oil leaks in this area may also originate from rocker cover gaskets, breather connections or other engine components, so the source should be confirmed before replacement.
Recommended During Rocker Cover Gasket Replacement
Whenever the rocker covers are removed, it's a good opportunity to inspect the half moon seals and replace any that have hardened or deteriorated.
Replacing the seals during rocker cover gasket servicing can help reduce the risk of having to repeat the job due to oil leaks from ageing rubber components.
This genuine Nissan half moon seal is a useful addition to:
- Rocker cover gasket replacements
- Cam cover resealing
- RB20, RB25 and RB26 engine maintenance
- Engine rebuilds and cylinder head servicing
- Repairs involving oil leaks at the rear of the cylinder head
- Preventative maintenance on ageing Nissan engines
Quantity Required – Please Read
This product is sold individually.
- Quantity supplied: 1 Half Moon Seal
- Quantity required for a complete engine reseal: 2 Half Moon Seals
Please add a quantity of two (2) to your cart if replacing both half moon seals.
Rocker cover gaskets, sealants and additional sealing components are sold separately.
Installation Information
Correct installation is important to ensure effective sealing and prevent oil leaks.
Before fitting the new seal, thoroughly clean the applicable cylinder head sealing recess and inspect the surrounding surfaces for damage or contamination.
Install the half moon seal in the correct orientation and follow the applicable Nissan factory workshop procedure, including any specified sealant application at sealing surface junctions.
Avoid damaging or displacing the seal when reinstalling the rocker cover.
Professional installation is recommended.
Why Choose Genuine Nissan?
Genuine Nissan replacement seals are manufactured to original equipment specifications, providing the dimensions, material characteristics and factory-style fitment required for compatible engines.
For classic Nissan performance engines such as the RB26DETT, genuine sealing components are an excellent choice for maintaining originality and addressing age-related oil leaks.
Note: This listing includes one (1) Genuine Nissan Rocker Cover Half Moon Seal – 11051-58S00 only. Two (2) seals are required for a complete engine reseal. Rocker cover gaskets, sealants and additional components are not included. Supplied in genuine Nissan OEM packaging, which may be removed for product photography.
Australian Stock & Fast Dispatch: At OEM4JDM, every part listed as In Stock is physically on our shelf in Australia and ready for fast dispatch.