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Radial Seal / RMS / Camshaft / Balance shaft
Fitting Position: Transmission End
Inner Diameter: 90 mm, Outer diameter: 110 mm, Width: 12 mm
Radial Shaft Seal Design.
Fits:
Porsche 911 3.0L 1978 - 1983
Porsche 911 3.2L 1984 - 1989
Porsche 930 Turbo 1975 - 1989
Diagram Ref No 33
The rear main oil seal fits at the rear of the crankshaft where it passes through the engine case. It helps retain engine oil inside the crankcase and prevents oil from leaking into the flywheel, clutch, or transmission bellhousing area.
Functions
• Replaces the rear crankshaft oil seal
• Helps seal the rear of the engine crankshaft
• Helps prevent engine oil leaks from the bellhousing area
• Protects the clutch and flywheel area from oil contamination
• Supports correct crankcase oil retention
• Replaces hardened, worn, split, leaking, or damaged original seals
• OE Match replacement for Porsche 911 and 930 engine service.
Why Replace This Part?
Rear main oil seals are exposed to heat, crankshaft rotation, oil, pressure changes, and age-related wear. Over time, the seal can harden, shrink, crack, wear, or lose sealing ability. A failed rear main seal may cause oil leaks between the engine and gearbox, oil contamination on the clutch, burning oil smells, or visible oil dripping from the bellhousing area. Replacing the seal helps restore a clean, reliable crankshaft seal.
When to Replace This Part
• Oil is leaking from between the engine and gearbox
• Oil drips are visible from the bellhousing area
• The clutch or flywheel is contaminated with oil
• The engine or gearbox has been removed
• The flywheel is being removed or replaced
• The original seal is hardened, worn, split, or leaking
• Preventative replacement is being carried out during clutch or engine service.
Where it fits on the car
This oil seal fits at the rear crankshaft position on Porsche 911 and 930 engines. It sits between the crankshaft and engine case, behind the flywheel area.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99911342641
The product you are viewing cross references to these numbers
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
Fitting Position: Transmission End,
Inner Diameter: 90 mm,
Outer diameter: 110 mm,
Width: 12 mm, Radial Shaft Seal Design.
Fits:
Porsche 911 3.0L 1978 - 1983
Porsche 911 3.2L 1984 - 1989
Porsche 930 Turbo 1975 - 1989
Diagram Ref No 33
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99911342642
The product you are viewing cross references to these numbers
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
Radial Oil Seals – Precision Engine Sealing for Porsche Performance and Reliability
The radial oil seals in your Porsche engine — including the rear main seal, camshaft seal, balance shaft seal, and crankshaft seal — are critical to maintaining oil pressure, preventing leaks, and protecting your engine’s moving components. These seals keep lubricating oil contained within the engine while keeping out dust and contaminants, ensuring smooth operation and long-term reliability.
At Design911, we offer a complete range of radial oil seals developed for exceptional fitment and performance across classic and modern Porsche models. Manufactured from high-grade elastomers and reinforced materials, these seals withstand extreme temperatures, oil pressure, and rotational speeds. Whether you’re rebuilding a classic 911 engine or maintaining a modern turbocharged model, our manufacturer-quality seals provide the leak-free performance your Porsche deserves.
What Do Radial Oil Seals Do?
Radial oil seals (also known as shaft seals or lip seals) provide a vital barrier between rotating and stationary engine components.
Core Functions:
- Seal
engine oil within the crankcase and camshaft housings.
- Prevent
external contaminants from entering the lubrication system.
- Maintain
correct oil pressure for optimal engine performance.
- Reduce
friction and wear on critical rotating components.
- Enhance engine longevity by ensuring consistent lubrication.
Each seal — whether on the crankshaft, camshaft, or balance shaft — contributes to maintaining an efficient, leak-free lubrication system.
Why Do Radial Oil Seals Fail?
Over time, oil seals are exposed to high heat, pressure, and chemical degradation, which can cause them to harden or crack. Once they lose flexibility, oil begins to escape — leading to contamination, reduced lubrication, and potential engine damage.
Common Causes of Failure Include:
- Age-related
hardening and loss of elasticity.
- Excessive
crankcase pressure from blocked breathers.
- Oil
contamination that breaks down sealing material.
- Heat
and friction causing surface wear.
- Improper installation or alignment issues during rebuilds.
Typical signs of failure include oil leaks around the rear of the engine, oil spots under the car, or visible seepage near timing covers or crankshaft pulleys. Addressing these early prevents more serious damage.
Why Replace Radial Seals?
Replacing worn or leaking radial oil seals is essential for preventing oil loss and protecting your Porsche engine’s internal components. Our high-performance seals are designed to meet or exceed manufacturer standards for sealing efficiency, durability, and temperature resistance.
Key Benefits:
- Restores proper oil sealing and pressure.
- Prevents leaks and contamination.
- Resists high heat, oil exposure, and chemical degradation.
- Reduces wear on crankshaft and camshaft housings.
- Ensures long-term reliability and performance.
- Direct-fit compatibility for Porsche 911, Cayman, Boxster, Panamera, Cayenne and more.
Replacing these seals during engine service or rebuilds helps preserve oil integrity, reduce emissions, and protect against costly repairs.
Highlights:
- High-quality radial oil seals for Porsche engines.
- Rear main, camshaft, balance shaft, and crankshaft seal options.
- Heat- and oil-resistant construction for maximum longevity.
- Designed to handle high RPM and oil pressure conditions.
- Perfect for rebuilds, upgrades, and preventive maintenance.
- Engineered for a precision fit and long-term leak-free operation.