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Porsche // 928 (1978-1995) // Any
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Crankshaft Main Bearing O-Ring, 51x 4.5. Porsche 911 78-89 / 964 / 993 / 996 Turbo / 997 Turbo / GT3 - 99970728541
99970728541/1
Vehicle Group
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- 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 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 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
- Porsche 997 MK1 TURBO 2007-09
- Porsche 997 MK1 GT3 / GT3 RS 2007-09
- Porsche 997 MKII GT3 / GT3 RS 2010-11
- Porsche 997 MKII Turbo 2010-13
Information
Crankshaft Main Bearing O-Ring, 51x 4.5
This OE Match crankshaft main bearing O-ring is a replacement sealing ring for Porsche 911 1978–1989, 964, 993, 996 Turbo, 997 Turbo, and GT3 models. Measuring 51 x 4.5, it is designed to match the original-style fitment and sealing function within the crankshaft / main bearing area.
Sold individually
Fits:
Porsche 911 1978 - 1989
Porsche 964 1989 - 1994
Porsche 993 1995 - 1998
Porsche 996 Turbo 3.6L 2001 - 2005
Porsche 996 GT3 3.6L 1999 - 2005
Porsche 997.1 Turbo 3.6L 2007 - 2009
Porsche 997.2 Turbo 3.6L 2010 - 2013
Porsche 997 GT3 3.6L / 3.8L / 4.0L 2007 - 2011
Diagram ref no 21
The crankshaft main bearing O-ring helps seal the relevant bearing or housing connection to prevent oil leakage and maintain correct engine oil sealing. A properly sealing O-ring is essential for protecting engine components and maintaining oil system integrity.
What This Part Does / Functions
• Replaces the crankshaft main bearing
• O-ring Helps seal the crankshaft / main bearing housing area
• Supports correct engine oil sealing
• Helps prevent oil leaks from aged or flattened seals
• Suitable for engine rebuild, crankshaft, or bearing service
• Replaces hardened, cracked, flattened, swollen, or damaged O-rings
• OE Match replacement for Porsche engine sealing repair.
Why Replace This Part?
O-rings can harden, flatten, crack, swell, or lose sealing ability due to heat, age, oil exposure, pressure, and engine service work. A worn or damaged crankshaft main bearing O-ring may allow oil seepage or leakage, affecting engine cleanliness and oil system reliability. Replacement is recommended whenever the related engine components are removed or when oil leakage is present.
When to Replace This Part
• Engine rebuild or major engine service is being carried out
• Crankshaft or main bearing components are being serviced
• Oil leakage is present around the related sealing area
• The original O-ring is hardened, flattened, cracked, or damaged
• Bearing housing or crankshaft sealing components have been removed
• Preventative replacement is required during engine assembly
• The vehicle is undergoing Porsche engine restoration
Where it fits on the car
This O-ring fits within the engine crankshaft / main bearing sealing area. Exact position can vary depending on engine type and model-specific crankcase layout.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99970728541
The product you are viewing cross references to these numbers
This OE Match crankshaft main bearing O-ring is a replacement sealing ring for Porsche 911 1978–1989, 964, 993, 996 Turbo, 997 Turbo, and GT3 models. Measuring 51 x 4.5, it is designed to match the original-style fitment and sealing function within the crankshaft / main bearing area.
Sold individually
Fits:
Porsche 911 1978 - 1989
Porsche 964 1989 - 1994
Porsche 993 1995 - 1998
Porsche 996 Turbo 3.6L 2001 - 2005
Porsche 996 GT3 3.6L 1999 - 2005
Porsche 997.1 Turbo 3.6L 2007 - 2009
Porsche 997.2 Turbo 3.6L 2010 - 2013
Porsche 997 GT3 3.6L / 3.8L / 4.0L 2007 - 2011
Diagram ref no 21
The crankshaft main bearing O-ring helps seal the relevant bearing or housing connection to prevent oil leakage and maintain correct engine oil sealing. A properly sealing O-ring is essential for protecting engine components and maintaining oil system integrity.
What This Part Does / Functions
• Replaces the crankshaft main bearing
• O-ring Helps seal the crankshaft / main bearing housing area
• Supports correct engine oil sealing
• Helps prevent oil leaks from aged or flattened seals
• Suitable for engine rebuild, crankshaft, or bearing service
• Replaces hardened, cracked, flattened, swollen, or damaged O-rings
• OE Match replacement for Porsche engine sealing repair.
Why Replace This Part?
O-rings can harden, flatten, crack, swell, or lose sealing ability due to heat, age, oil exposure, pressure, and engine service work. A worn or damaged crankshaft main bearing O-ring may allow oil seepage or leakage, affecting engine cleanliness and oil system reliability. Replacement is recommended whenever the related engine components are removed or when oil leakage is present.
When to Replace This Part
• Engine rebuild or major engine service is being carried out
• Crankshaft or main bearing components are being serviced
• Oil leakage is present around the related sealing area
• The original O-ring is hardened, flattened, cracked, or damaged
• Bearing housing or crankshaft sealing components have been removed
• Preventative replacement is required during engine assembly
• The vehicle is undergoing Porsche engine restoration
Where it fits on the car
This O-ring fits within the engine crankshaft / main bearing sealing area. Exact position can vary depending on engine type and model-specific crankcase layout.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99970728541
99970146740
99970728540
99970728541
The product you are viewing cross references to these numbers
Price: £5.50
In stock
Related products
Vehicle Group
- Porsche 944S 2.5L 16V 1987-88
- Porsche 944S2 3.0L 16V 1989-91
- 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 928S 4.7L 1981-83
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
Information
Spark Plug Sealing Ring.
Fits:
Porsche 944 S / 944 S2 1987-91
Porsche 968 1992-95
Porsche 928 S / 928 S4 / 928 GT / 928 GTS 1985-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 7
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
92810444308
The product you are viewing cross references to these numbers
Fits:
Porsche 944 S / 944 S2 1987-91
Porsche 968 1992-95
Porsche 928 S / 928 S4 / 928 GT / 928 GTS 1985-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 7
Related reference numbers
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92810444308
92810444308
71-27159-00
712715900
The product you are viewing cross references to these numbers
Price: £1.30
In stock
Vehicle Group
- Porsche 944S 2.5L 16V 1987-88
- Porsche 944S2 3.0L 16V 1989-91
- 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 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
Information
Pressure ring for rocker cover
Fits:
Porsche 944 S / 944 S2 1987-91
Porsche 968 1992-95
Porsche 928 S4 / 928 GT / 928 GTS 1987-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 12.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
92810411502
The product you are viewing cross references to these numbers
Fits:
Porsche 944 S / 944 S2 1987-91
Porsche 968 1992-95
Porsche 928 S4 / 928 GT / 928 GTS 1987-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 12.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
92810411502
92810411502
92810411502
The product you are viewing cross references to these numbers
Price: £4.48
In stock
Vehicle Group
- 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
Information
Pilot bearing.
Fits:
Porsche 928 1978-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 2
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
92810211102
The product you are viewing cross references to these numbers
Fits:
Porsche 928 1978-95
Click 'Zoom in' for large parts diagram.
Diagram ref no 2
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
92810211102
92810211102
The product you are viewing cross references to these numbers
Price: £21.40
Orderable
Vehicle Group
- 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
Information
Crankshaft seal. 60 X 85 X 10 mm.
Front crankshaft seal also known as a shaft sealing ring. It sits at the front of the engine, sealing the point where the crankshaft passes through the engine block - typically behind the vibration damper or timing gear. Its purpose is to keep engine oil contained while allowing the crankshaft to spin freely.
Fits:
Porsche 928 1978 - 1995
Diagram ref no 3
Over time, the crankshaft seal can wear down from constant heat, oil exposure, and friction. The rubber lip may harden, crack, or become damaged, losing its ability to seal properly. When this happens, oil begins to leak, which can create a mess, damage engine components, or cause belts and pulleys to slip if oil spreads across them.
How to Know If It’s Failing:
You might suspect the seal is failing if you notice:
• Oil dripping or forming a puddle under the front section of the engine.
• Visible oil seepage around the crankshaft front seal area.
• Smoke or burning smell under the hood (oil hitting a hot surface). Low oil levels without visible external damage.
• After so many miles or long periods without seal maintenance, even if there’s not a massive leak yet.
If a worn front crankshaft seal isn’t replaced, the oil leak will usually worsen over time. This can lead to significant oil loss and starve the engine of proper lubrication, causing serious internal damage. Leaking oil may also spread onto belts and pulleys, leading to slippage, premature wear, or even belt failure. In addition to making a mess and degrading nearby components, oil on hot surfaces can pose a fire hazard. Left unchecked, the problem often becomes more expensive to fix, especially if the leak reaches sensors, wiring, or other critical parts.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99911326340
The product you are viewing cross references to these numbers
Front crankshaft seal also known as a shaft sealing ring. It sits at the front of the engine, sealing the point where the crankshaft passes through the engine block - typically behind the vibration damper or timing gear. Its purpose is to keep engine oil contained while allowing the crankshaft to spin freely.
Fits:
Porsche 928 1978 - 1995
Diagram ref no 3
Over time, the crankshaft seal can wear down from constant heat, oil exposure, and friction. The rubber lip may harden, crack, or become damaged, losing its ability to seal properly. When this happens, oil begins to leak, which can create a mess, damage engine components, or cause belts and pulleys to slip if oil spreads across them.
How to Know If It’s Failing:
You might suspect the seal is failing if you notice:
• Oil dripping or forming a puddle under the front section of the engine.
• Visible oil seepage around the crankshaft front seal area.
• Smoke or burning smell under the hood (oil hitting a hot surface). Low oil levels without visible external damage.
• After so many miles or long periods without seal maintenance, even if there’s not a massive leak yet.
If a worn front crankshaft seal isn’t replaced, the oil leak will usually worsen over time. This can lead to significant oil loss and starve the engine of proper lubrication, causing serious internal damage. Leaking oil may also spread onto belts and pulleys, leading to slippage, premature wear, or even belt failure. In addition to making a mess and degrading nearby components, oil on hot surfaces can pose a fire hazard. Left unchecked, the problem often becomes more expensive to fix, especially if the leak reaches sensors, wiring, or other critical parts.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99911326340
99911326340
19409
The product you are viewing cross references to these numbers
Price: £24.00
In stock