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Radial Seal / RMS / Camshaft / Balance shaft
By OE Match
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
- Porsche 996 TURBO 2000-05
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 924S 2.5L 1986-87
- Porsche 924S 2.5L 1988
- Porsche 944 2.5L 8V 1982-87
- Porsche 944 2.7L 8V 1988-89
- Porsche 944S 2.5L 16V 1987-88
- Porsche 944S2 3.0L 16V 1989-91
- Porsche 944 Turbo 2.5L 8V 1985-88
- Porsche 944 Turbo 2.5L 8V 1989-91
- Porsche 944 Turbo S 2.5L 8V 1988
- Porsche 968 3.0L 1992-94
- Porsche 968 Sport 3.0L 1994-95
- Porsche 968 CS 3.0L 1993-95
- Porsche 968 Turbo S 3.0L 1993-94
- Porsche 928 4.5L 1978-82
- Porsche 928S 4.7L 1981-83
- Porsche 928S2 4.7L 1984-86
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
Restore engine sealing integrity and prevent costly oil leaks with this OE Match Rear Main Oil Seal for the Porsche 964, Porsche 993 and Porsche 996. Manufactured to OE specifications and measuring 90mm inner diameter, 110mm outer diameter and 12mm width, this critical engine seal is designed to prevent engine oil escaping around the rear of the crankshaft where it exits the engine case and connects to the flywheel assembly.
Fits:
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
- Porsche 996 TURBO 2000-05
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 924S 2.5L 1986-87
- Porsche 924S 2.5L 1988
- Porsche 944 2.5L 8V 1982-87
- Porsche 944 2.7L 8V 1988-89
- Porsche 944S 2.5L 16V 1987-88
- Porsche 944S2 3.0L 16V 1989-91
- Porsche 944 Turbo 2.5L 8V 1985-88
- Porsche 944 Turbo 2.5L 8V 1989-91
- Porsche 944 Turbo S 2.5L 8V 1988
- Porsche 968 3.0L 1992-94
- Porsche 968 Sport 3.0L 1994-95
- Porsche 968 CS 3.0L 1993-95
- Porsche 968 Turbo S 3.0L 1993-94
- Porsche 928 4.5L 1978-82
- Porsche 928S 4.7L 1981-83
- Porsche 928S2 4.7L 1984-86
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
Diagram Ref No. 21
The rear main oil seal, often referred to as the RMS (Rear Main Seal), is one of the most important sealing components in the engine. It retains engine oil inside the crankcase while allowing the crankshaft to rotate at high speed. A worn or damaged seal can lead to oil leaks, clutch contamination and unnecessary engine maintenance costs if left unattended.
This OE Match replacement provides the correct fit, sealing performance and durability required for maintenance, engine rebuilds and preventative servicing.
What Does the Rear Main Oil Seal Do?
The rear main oil seal forms a seal around the rear section of the crankshaft.
Its primary functions include:
- Preventing engine oil leaks
- Sealing the rear crankshaft opening
- Protecting the flywheel area from contamination
- Maintaining correct engine oil levels
- Preventing oil reaching the clutch assembly
- Supporting long-term engine reliability
- Allowing smooth crankshaft rotation
Without a properly functioning rear main seal, oil can escape from the engine and create a range of reliability issues.
Why Do Rear Main Oil Seals Fail?
Like all rubber sealing components, rear main oil seals are subject to wear and ageing.
Common causes of failure include:
- Heat cycling
- Age-related hardening
- Crankshaft wear
- Engine vibration
- Long-term oil exposure
- Improper installation
- Excessive crankcase pressure
- High mileage use
Over time, the sealing lip can lose flexibility and its ability to maintain consistent contact with the crankshaft surface.
Symptoms of a Failing Rear Main Oil Seal
Common warning signs include:
- Oil leaks between engine and gearbox
- Oil drips beneath the vehicle
- Oil contamination around the flywheel housing
- Clutch slip caused by oil contamination
- Burning oil smell
- Gradual oil level loss
- Oil residue on transmission bellhousing
Because the seal is located behind the flywheel, leaks can often be mistaken for other engine oil leaks unless properly diagnosed.
When Should the Rear Main Oil Seal Be Replaced?
Replacement is recommended when:
- Oil leakage is present
- The gearbox is being removed
- Replacing the clutch assembly
- Rebuilding the engine
- Refurbishing the crankshaft
- Carrying out preventative maintenance
- The original seal shows signs of ageing
- Engine mileage is high
Many Porsche specialists recommend replacing the rear main seal whenever the clutch or flywheel is removed, as labour access is significantly easier during these procedures.
Why Replacement Matters
A leaking rear main oil seal can lead to far more expensive repairs if ignored.
Benefits of replacement include:
- Prevention of engine oil leaks
- Protection of the clutch assembly
- Improved engine cleanliness
- Reduced maintenance costs
- Improved reliability
- Professional rebuild standards
- Long-term sealing performance
- Greater peace of mind
Replacing the seal during clutch or engine work is considered a smart preventative maintenance measure.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99911342642
The product you are viewing cross references to these numbers
OEMatch Radial Seal / RMS / Camshaft / Balance shaft — Durability, Sealing, Performance
For Porsche models, radial oil seals including rear main, camshaft, crankshaft and balance shaft seals keep lubricating oil contained, exclude contaminants and protect rotating components. Regular inspection and correct replacement reduce leakage risk, help maintain oil pressure and support long service life during routine maintenance or engine rebuilds.
Available Types
- Rear main seal
- Crankshaft seal
- Camshaft seal
- Balance shaft seal
Understanding OEMatch Radial Seal / RMS / Camshaft / Balance shaft
OEM (Original Equipment Manufacturer) parts are made by the same company that produced your Porsche’s original radial seals.
OE (Original Equipment) refers to parts matching original specifications for the radial seals and may be supplied by alternative manufacturers. Aftermarket parts offer alternative options, sometimes with enhanced features or better value. OEMatch supplies non-OEM radial seals engineered as direct-fit alternatives to OEM parts, made to original-spec dimensions and tolerances for Porsche models.
Radial seals form a lip contact against rotating shafts to retain oil and exclude dirt and moisture. They are typically made from elastomeric materials combined with a metal case and a spring to maintain sealing pressure. Selection of the correct seal material and design is important to resist heat, oil contamination and shaft speed seen in Porsche engines.
Benefits Include
- Restores reliable oil containment and helps maintain correct oil pressure
- Protects bearings, housings and timing components from contamination
- Materials selected to resist heat, oil and ageing where applicable
Why Radial Seal / RMS / Camshaft / Balance shaft Wear and Fail
- Age-related hardening and loss of elastomer flexibility
- Excessive crankcase pressure or blocked breathers forcing oil past the lip
- Oil contamination or chemical degradation of the seal material
- Incorrect installation, misalignment or damaged sealing faces
The Importance of Replacing with OEMatch Radial Seal / RMS / Camshaft / Balance shaft
Addressing worn or leaking seals promptly prevents progressive oil loss and contamination that can damage bearings, camshaft journals and crankcases. Correct replacement restores sealing integrity during service or rebuild work and reduces the chance of secondary damage or repeated repairs. Choosing seals suitable for Porsche engine conditions supports consistent lubrication and reduces workshop time diagnosing recurrent leaks.
Advantages
- Direct-fit replacements engineered to match original dimensions and tolerances where applicable
- Options selected for compatibility with Porsche engine layouts and service procedures
- Variety of seal types to cover rear main, crankshaft, camshaft and balance shaft applications