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- Porsche 911 1987-1989 3.2L G50
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
Fits:
Porsche 911 3.2L 1987-89 (G50 Gearbox)
Porsche 964 3.6L Carrera (G50 Gearbox)
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
93010203303
The product you are viewing cross references to these numbers
- 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
Fits:
Porsche 968 3.0L 1992-95
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
94411401201
The product you are viewing cross references to these numbers
- 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
Rear Main Oil Seal for Porsche
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.
99911342641
The product you are viewing cross references to these numbers
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1978-1989 3.3L Turbo (930)
- 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 997 MK1 TURBO 2007-09
- Porsche 997 MK1 GT3 / GT3 RS 2007-09
- Porsche 924 Turbo 2.0L 1979-81
- Porsche 924 Turbo 2.0L 1982-84
- 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
Fits:
Porsche 911 1989 Onwards 930.66 / 930.68
Porsche 911 (930) Turbo 1989 Onwards 930.66 / 930.68
Porsche 924 Turbo 1976-85
Porsche 924S 1986-88
Porsche 944 1982-91
Porsche 968 1992-95
Porsche 964 1989-94
Porsche 997 Turbo 2007-09
Porsche 997 GT3 I004 (RS version) 2007-11
Click 'Zoom in' for large parts diagram.
Diagram ref no 3.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
93110211102
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