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Crankcase through bolt o-ring. Porsche 911 1965-89 - 99970100640
99970100640/1
Vehicle Group
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- 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)
Information
Crankcase Through Bolt O-Ring
Sold each - 24 required per engine
The Porsche Crankcase Through Bolt O-Ring is a
small but critically important sealing component used in Porsche 911 engines
from 1965 to 1989. Fitted around the crankcase through bolts that secure the
engine case halves together, this O-ring helps prevent oil leakage from one of
the most common sealing points found on classic air-cooled Porsche engines.
Fits:
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- 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)
Diagram ref no 22
Although inexpensive, these O-rings play a vital role in maintaining the integrity of the engine lubrication system. When properly installed, they create a reliable seal around the through bolts, preventing pressurised engine oil from escaping the crankcase and helping to keep the engine clean and leak-free.
Whether you're performing a complete engine rebuild, repairing oil leaks, or restoring a classic Porsche 911, replacing the crankcase through bolt O-rings is considered essential preventative maintenance.
What Does the Crankcase Through Bolt O-Ring Do?
The through bolt O-ring seals the openings where the crankcase through bolts pass through the engine case.
Its primary functions include:
- Preventing oil leaks from the crankcase
- Maintaining crankcase sealing integrity
- Supporting proper oil system operation
- Helping preserve engine cleanliness
- Reducing oil loss and contamination
- Protecting engine components from oil seepage
Because Porsche air-cooled engines operate with a high-capacity dry-sump lubrication system, maintaining effective sealing throughout the crankcase is crucial for long-term reliability.
Why Does the Through Bolt O-Ring Fail?
Over time, the O-ring is exposed to extreme engine heat, oil, pressure fluctuations, and age-related deterioration.
Common causes of failure include:
- Rubber hardening due to heat cycles
- Age-related shrinkage
- Loss of elasticity
- Oil exposure over decades of use
- Improper installation
- Damage during assembly
- Long-term storage and inactivity
As the O-rings age, they gradually lose their sealing ability and become one of the most common sources of oil leaks on classic Porsche 911 engines.
Common Symptoms of a Failing Through Bolt O-Ring
Signs that the O-rings may require replacement include:
- Oil leaks around the crankcase
- Oil residue underneath the engine
- Persistent oil drips despite replacing other seals
- Oil staining around through bolt locations
- Excessive oil mist accumulation on the engine case
- Leaks becoming worse as the engine reaches operating temperature
These leaks are often mistaken for rocker cover, timing chain housing, or crankshaft seal leaks due to the way oil travels across the engine casing.
When Should You Replace It?
Replacement is strongly recommended whenever the engine is disassembled.
The through bolt O-rings should always be replaced:
- During complete engine rebuilds
- During crankcase splitting procedures
- When repairing major oil leaks
- During full engine restorations
- On high-mileage engines undergoing overhaul
- Whenever the crankcase through bolts are removed
- As preventative maintenance during engine refurbishment
Because access requires significant engine disassembly, replacing these O-rings during rebuild work is considered standard Porsche engine-building practice.
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Information
HEX HEAD BOLT M12X1,5X110MM (extra long)
This Item is an Original Porsche Part found by using our original Porsche Part Number Search. If you are ordering parts via this method it is your responsibility to make sure that you enter and purchase the correct products for your vehicle. Please only use the searched product if you are sure of the part numbers as parts cannot be returned if ordered incorrectly.
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90008214201L
The product you are viewing cross references to these numbers
This Item is an Original Porsche Part found by using our original Porsche Part Number Search. If you are ordering parts via this method it is your responsibility to make sure that you enter and purchase the correct products for your vehicle. Please only use the searched product if you are sure of the part numbers as parts cannot be returned if ordered incorrectly.
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Vehicle Group
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 2.7L 2005-08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche Boxster 987 MKII 2.9L 2009-12
- Porsche Boxster S 987 MKII 3.4L 2009-12
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- Porsche Boxster S 718 2.5L Manual (350 Bhp) 05/2017>>
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- Porsche Boxster T 718 2.0L Manual (300 Bhp) 01/2019>>
- Porsche Boxster T 718 2.0L PDK (300 Bhp) 01/2019>>
- Porsche Boxster GTS 718 2.5L Manual (365 Bhp) 05/2017>>
- Porsche Boxster GTS 718 2.5L PDK (365 Bhp) 05/2017>>
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- 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 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 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
- Porsche 996 C4S 3.6L 09/01-2005
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08
- Porsche 997 MK1 Carrera 4S 3.8L 2005-08
- Porsche Cayman 718 2.0L Manual (300 Bhp)
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- Porsche Cayman T 718 2.0L Manual (300 Bhp)
- Porsche Cayman T 718 2.0L PDK (300 Bhp)
- Porsche Cayman GTS 718 2.5L Manual (365 Bhp)
- Porsche Cayman GTS 718 2.5L PDK (365 Bhp)
Information
High performance stud + nut kits for the exhaust manifold to cylinder head for Porsche. Using titanium and Inconel alloy studs, aerospace lock nuts, and a well-thought and balanced combination of metals and plating/coatings, our fasteners will perform better than the traditional fastener. They will never oxidize, and hence will unscrew easily when required.
Novel ultra-high-performance product
• Use of Titanium Ti6Al4V technology
• Extreme perceived quality
Contains 12 x Studs, Nuts & Washers
Fits:
Porsche 911 1965-77
Porsche 964 (none Turbo)
Porsche 993 All
Porsche 996 (none Turbo)
Porsche 997 (none Turbo)
Porsche 986 All
Porsche 987 All
Porsche 718 4 Cyl Turbo
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Contains 12 x Studs, Nuts & Washers
Fits:
Porsche 911 1965-77
Porsche 964 (none Turbo)
Porsche 993 All
Porsche 996 (none Turbo)
Porsche 997 (none Turbo)
Porsche 986 All
Porsche 987 All
Porsche 718 4 Cyl Turbo
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Vehicle Group
- Porsche Boxster 987 MKII 2.9L 2009-12
- Porsche Boxster S 987 MKII 3.4L 2009-12
- Porsche Boxster 981 2.7L 2012-16
- Porsche Boxster 981 S / GTS 3.4L 2012-16
- Porsche Boxster 981 Spyder 3.8L 2016
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- Porsche Boxster S 718 2.5L Manual (350 Bhp) 05/2017>>
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- Porsche Boxster GTS 718 2.5L Manual (365 Bhp) 05/2017>>
- Porsche Boxster GTS 718 2.5L PDK (365 Bhp) 05/2017>>
- Porsche 996 TURBO 2000-05
- Porsche 996 GT2 2001-05
- 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 MK1 GT2 2007-09
- Porsche 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII Carrera C4S 3.8L 2009-12
- Porsche 997 MKII GT3 / GT3 RS 2010-11
- Porsche 997 MKII Turbo 2010-13
- Porsche 997 MKII GT2 RS 2011-13
- Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Turbo 3.8L (520 Bhp) 2014-16
- Porsche 991.1 Turbo S 3.8L (560 Bhp) 2014-16
- Porsche 991.1 R 4.0L (500 Bhp) 2016
- Porsche 991.1 GT3 3.8L (475 Bhp) 2014-16
- Porsche 991.1 GT3 RS 4.0L (500 Bhp) 2015-16
- Porsche 991.2 Carrera 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 2S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Carrera 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Targa 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Targa 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Turbo Coupe 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Coupe 3.8L (580 Bhp) 2016-19
- Porsche 991.2 Turbo Cabriolet 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Cabriolet 3.8L (580 Bhp) 2016-19
- Porsche 991.2 Speedster 4.0L (510Bhp) 2019
- Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19
- Porsche 991.2 GT2 RS 3.8L PDK (700 bhp) 2018-19
- Porsche 992.1 Carrera 2 3.0L 2019-24
- Porsche 992.1 Carrera 4 3.0L 2019-24
- Porsche 992.1 Carrera 2 Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 4 Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 2S / GTS 3.0L 2019-24
- Porsche 992.1 Carrera 4S / GTS 3.0L 2019-24
- Porsche 992.1 Carrera 2S / GTS Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 4S / GTS Cabriolet 3.0L 2019-24
- Porsche 992.1 Targa 4 3.0L 2020-24
- Porsche 992.1 Targa 4S / GTS 3.0L 2020-24
- Porsche 992.1 Speedster 4.0L 2019-24
- Porsche 992.1 Turbo 3.8L 2020-24
- Porsche 992.1 Turbo S 3.8L 2020-24
- Porsche 992.1 Turbo Cabriolet 3.8L 2020-24
- Porsche 992.1 Turbo S Cabriolet 3.8L 2020-24
- Porsche 992.1 GT3 4.0L / 992 S/T 4.0L 2021-24
- Porsche Cayman 2.9L 987C MKII 2009-12
- Porsche Cayman S / R 3.4L 987C MKII 2009-12
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
- Porsche Cayman GT4 718 4.0L / GT4 RS 718 4.0L
Information
High performance stud + nut kits for the exhaust manifold to cylinder head for Porsche. Using titanium and Inconel alloy studs, aerospace lock nuts, and a well-thought and balanced combination of metals and plating/coatings, our fasteners will perform better than the traditional fastener. They will never oxidize, and hence will unscrew easily when required.
Novel ultra-high-performance product
• Use of Titanium Ti6Al4V technology
• Extreme perceived quality
Contains 18 x Studs, Nuts & Washers
Fits:
Porsche 996 Turbo / GT3 / GT2
Porsche 997 Turbo / GT3 / GT2
Porsche 997.2 ALL
Porsche 991 ALL
Porsche 992 ALL
Porsche 987 2009-12
Porsche 981
Porsche 718 GT4
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Contains 18 x Studs, Nuts & Washers
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Porsche 981
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Vehicle Group
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 2.7L 2005-08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche Boxster 987 MKII 2.9L 2009-12
- Porsche Boxster S 987 MKII 3.4L 2009-12
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- Porsche Boxster S 718 2.5L Manual (350 Bhp) 05/2017>>
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- Porsche Boxster T 718 2.0L Manual (300 Bhp) 01/2019>>
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- Porsche Boxster GTS 718 2.5L Manual (365 Bhp) 05/2017>>
- Porsche Boxster GTS 718 2.5L PDK (365 Bhp) 05/2017>>
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- 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 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 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
- Porsche 996 C4S 3.6L 09/01-2005
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08
- Porsche 997 MK1 Carrera 4S 3.8L 2005-08
Information
High performance stud + nut kits for the exhaust manifold to cylinder head for Porsche. Using titanium and Inconel alloy studs, aerospace lock nuts, and a well-thought and balanced combination of metals and plating/coatings, our fasteners will perform better than the traditional fastener. They will never oxidize, and hence will unscrew easily when required.
Novel ultra-high-performance product
• Use of Inconel 718 and aerospace technology
• Extreme perceived quality
Contains 12 x Studs, Nuts & Washers
Fits:
Porsche 911 1965-77
Porsche 964 (non Turbo)
Porsche 993 All
Porsche 996 (non Turbo)
Porsche 997 (non Turbo)
Porsche 986 All
Porsche 987 All
Porsche 718 4 Cyl Turbo
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• Use of Inconel 718 and aerospace technology
• Extreme perceived quality
Contains 12 x Studs, Nuts & Washers
Fits:
Porsche 911 1965-77
Porsche 964 (non Turbo)
Porsche 993 All
Porsche 996 (non Turbo)
Porsche 997 (non Turbo)
Porsche 986 All
Porsche 987 All
Porsche 718 4 Cyl Turbo
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