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Engine Bolts / Studs
By OE Match
- 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)
- 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
PACK OF 12. Normally 24 studs per engine.
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98
This product supersedes Porsche's old part numbers:
- 99310117051
Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case.
Click 'Zoom in' for large parts diagram.
Diagram Ref No 2.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
This kit is comprised of the following items:
- 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)
- 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
PACK OF 24. Normally 24 studs per engine.
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98
This product supersedes Porsche's old part numbers:
- 99310117051
Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case.
Click 'Zoom in' for large parts diagram.
Diagram Ref No 2.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
This kit is comprised of the following items:
- 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)
- 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
This complete set of 24 Dilavar cylinder head studs replaces all major head fasteners on air-cooled Porsche flat-six engines. Ideal for full rebuilds, upgrades, or resolving broken stud issues, the set provides factory-spec strength, corrosion resistance, and thermal stability. Fits 911, 964, and 993 engines (1965–98).
SET OF 24 STUDS (Original Porsche Quality)
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
Diagram Ref No 2.
Aged factory head studs can crack, corrode, or lose tension - especially after decades of heat cycling. Failure of a head stud can cause head leaks, combustion pressure loss, broken cylinders, or catastrophic engine damage. Installing new Dilavar studs ensures proper sealing, correct torque values, and long-term engine reliability.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
This kit is comprised of the following items:
- 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)
- 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
A 12-piece Dilavar head stud set suitable for partial rebuilds, top-end refreshes, or replacing failed studs on one side of the engine. Provides the same high-strength, heat-stable performance as original Porsche Dilavar hardware. Fits air-cooled 911, 964, and 993 engines.
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
Diagram ref no 11
Aged factory head studs can crack, corrode, or lose tension - especially after decades of heat cycling. Failure of a head stud can cause head leaks, combustion pressure loss, broken cylinders, or catastrophic engine damage. Installing new Dilavar studs ensures proper sealing, correct torque values, and long-term engine reliability.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
This kit is comprised of the following items:
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 914 (1970-1976)
24 per engine.
Fits:
Porsche 911 1965-1968 2.0L / 912 SWB (F)
Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
(Not 1973 2.7L Carrera)
Porsche 914-6 1970-72
Diagram ref No 5
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90110117203
The product you are viewing cross references to these numbers
This kit is comprised of the following items:
- 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)
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.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99970100640
The product you are viewing cross references to these numbers
- 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)
- Porsche 914 (1970-1976)
Fits:
Porsche 911 1965-89
Porsche 914-6 1970-76
Click 'Zoom in' for large parts diagram.
Diagram ref no 23
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90110116103
The product you are viewing cross references to these numbers
- 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)
- Porsche 356B 1959-63
- Porsche 356C 1963-65
Cylinder Head Nut
Sold each - 24 required for the 911
Maintain the integrity and reliability of your Porsche
engine rebuild with this OE Match Cylinder Head Nut 90110438204. Designed for
use on Porsche 356B, 356C, 912 and classic 911 air-cooled engines, this
precision-engineered fastener plays a critical role in securing the cylinder
head assembly to the engine.
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)
- Porsche 356B 1959-63
- Porsche 356C 1963-65
Diagram Ref No 17
Although small in size, cylinder head nuts are among the most important fasteners in any engine. They provide the clamping force required to maintain an effective seal between the cylinder heads, cylinders and engine case, ensuring correct compression, combustion efficiency and long-term engine reliability.
Manufactured to OE Match specifications, this cylinder head nut is ideal for engine rebuilds, top-end overhauls, cylinder head refurbishment and concours restorations.
What Does a Cylinder Head Nut Do?
The cylinder head nut secures the cylinder head assembly to the engine using the cylinder head studs.
Its primary functions include:
- Maintaining cylinder head clamping force
- Ensuring correct cylinder sealing
- Supporting combustion chamber integrity
- Maintaining engine compression
- Preventing cylinder head movement
- Supporting reliable engine operation
- Helping prevent oil and combustion leaks
Correct clamping force is essential for maintaining engine performance and durability.
Why Do Cylinder Head Nuts Fail?
Cylinder head nuts are exposed to repeated heat cycles, vibration and engine loads throughout their service life.
Common causes of deterioration include:
- Corrosion
- Thread wear
- Fatigue from repeated heat cycles
- Over-tightening
- Incorrect installation procedures
- Engine overheating
- Age-related degradation
- Damage during previous rebuilds
In older air-cooled Porsche engines, decades of service can leave original hardware weakened or unsuitable for reuse.
Symptoms of Worn or Damaged Cylinder Head Hardware
Potential warning signs include:
- Loss of cylinder sealing
- Compression leaks
- Oil seepage around cylinder heads
- Difficulty achieving correct torque settings
- Damaged threads
- Corroded hardware
- Uneven clamping loads
- Engine rebuild inspection failures
Many of these issues are discovered during engine disassembly rather than during normal operation.
When Should Cylinder Head Nuts Be Replaced?
Replacement is strongly recommended when:
- Rebuilding an engine
- Carrying out a top-end overhaul
- Replacing cylinder head studs
- Refurbishing cylinder heads
- Corrosion is present
- Threads show signs of wear
- Factory specifications require replacement
Most professional Porsche engine builders replace critical fastening hardware during major engine work to ensure long-term reliability.
Why Replacement Matters
Reusing worn or damaged cylinder head hardware can compromise engine sealing and reliability.
Benefits of replacement include:
- Correct clamping force
- Improved sealing performance
- Reduced risk of leaks
- Improved engine reliability
- Professional rebuild standards
- Long-term durability
- Factory-correct restoration quality
- Greater peace of mind
For classic Porsche engines, replacing critical hardware is inexpensive insurance against future engine issues.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90110438204
The product you are viewing cross references to these numbers
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 356B 1959-63
- Porsche 356C 1963-65
The OE MATCH Cylinder Head Stud is a replacement engine fastening component designed to maintain secure cylinder head installation and reliable engine sealing on classic Porsche 356B, 356C and 912 models.
Fits:- Porsche 912
- Porsche 356 B
- Porsche 356 C
Diagram Ref No 2
Manufactured to match the original equipment design and specifications, this cylinder head stud forms an essential part of the engine's cylinder head retaining system, providing the clamping force required to hold the cylinder head and associated engine components securely in position.
The air-cooled four-cylinder engines fitted to the Porsche 356 and 912 operate under demanding conditions involving high combustion pressures, engine vibration and continuous temperature fluctuations. Maintaining correct cylinder head clamping is essential for preserving compression, preventing combustion gas leakage and supporting reliable engine performance.
The cylinder head stud works together with the appropriate retaining nuts and associated fastening hardware to maintain the intended compression and sealing between the cylinder head and cylinder assembly.
During normal engine operation, the cylinder head and surrounding components repeatedly expand and contract as temperatures rise and fall. The retaining studs must withstand these thermal cycles while maintaining sufficient clamping force to prevent unwanted movement or loss of sealing integrity.
Over time, original cylinder head studs can deteriorate due to corrosion, prolonged thermal exposure, mechanical fatigue, incorrect tightening or previous engine repairs. Worn, stretched, damaged or broken studs may reduce the clamping force applied to the cylinder head, potentially resulting in compression leaks, combustion gas leakage and increased mechanical stress on surrounding components.
Replacing a damaged or weakened cylinder head stud with an OE MATCH component helps restore the original fastening arrangement, maintain reliable cylinder head sealing and protect the engine against further damage.
Ideal for Porsche 356 and 912 engine rebuilding, cylinder head repairs, top-end overhauls and classic Porsche restoration projects.
What This Product Does:
The cylinder head stud is an essential mechanical fastening component within the engine assembly.
Its primary functions include:
- Secures the Cylinder Head: Provides the threaded fastening arrangement required to hold the cylinder head securely against the cylinder assembly.
- Maintains Cylinder Head Clamping Force: Works with the appropriate retaining nuts to maintain the specified clamping load.
- Supports Combustion Chamber Sealing: Helps maintain a secure connection between the cylinder head and cylinder to prevent combustion gases from escaping.
- Maintains Engine Compression: Supports the sealing integrity required for consistent cylinder compression.
- Prevents Unwanted Cylinder Head Movement: Helps keep the cylinder head correctly positioned during engine operation.
- Withstands Engine Temperature Changes: Accommodates the mechanical stresses caused by repeated heating and cooling cycles.
- Resists Combustion Forces: Helps maintain secure head retention under the high pressures generated during combustion.
- Supports Engine Structural Integrity: Contributes to the secure assembly of the cylinder head, cylinder barrel and associated engine components.
- Protects Engine Components: Helps reduce the risk of damage caused by loose or incorrectly secured cylinder heads.
- Maintains Original Equipment Configuration: Replaces the original fastening component while preserving the factory-style cylinder head assembly.
Symptoms Of Wear Or Failure:
Cylinder head studs are exposed to considerable mechanical forces, repeated thermal expansion, vibration and long-term engine operating stress.
Over time, these conditions can contribute to corrosion, thread damage, fatigue or mechanical failure.
Common symptoms of a worn, damaged or failing cylinder head stud include:
- Broken or Fractured Stud: The stud may snap or fracture due to fatigue, excessive stress or incorrect installation.
- Loose Cylinder Head: A damaged stud may prevent the cylinder head from maintaining the required clamping force.
- Loss of Engine Compression: Inadequate head clamping can allow combustion pressure to escape from the cylinder head sealing area.
- Combustion Gas Leakage: Escaping combustion gases may produce a distinctive ticking, puffing or chuffing noise around the cylinder head.
- Oil Seepage Around the Cylinder Head: Reduced clamping or associated sealing problems may contribute to oil leakage around the cylinder head or related components.
- Damaged or Stripped Threads: Thread wear may prevent the retaining nut from tightening correctly.
- Corroded Cylinder Head Studs: Severe corrosion can weaken the fastener or make removal difficult.
- Stud Stretching or Deformation: Excessive tightening or mechanical overload may permanently deform the stud.
- Difficulty Maintaining Correct Torque: Damaged threads or weakened fasteners may prevent correct tightening during engine assembly.
- Uneven Engine Running: Significant compression loss may contribute to rough idling, reduced power or inconsistent combustion.
- Unusual Engine Noises: Combustion leakage or movement around the cylinder head may cause abnormal engine noises.
- Visible Damage During Engine Rebuild: Inspection may reveal corrosion, thread deterioration, cracks or signs of previous overstressing.
- Damaged Crankcase Threads: A stud that has loosened or pulled from its mounting position may indicate damage to the threaded crankcase connection.
Why Replacement Matters:
Replacing a damaged, weakened or corroded cylinder head stud is important for maintaining cylinder head clamping, engine compression and long-term mechanical reliability.
Key Benefits of Replacement:
- Restores Cylinder Head Retention: Replaces damaged studs to help maintain secure cylinder head installation.
- Maintains Correct Clamping Force: Supports the specified fastening load required for reliable cylinder head sealing.
- Helps Prevent Compression Leaks: Maintains the correct clamping arrangement between the cylinder head and cylinder.
- Protects Against Combustion Gas Leakage: Reduces the risk of escaping combustion gases caused by inadequate head retention.
- Supports Consistent Engine Performance: Helps preserve the compression and sealing conditions required for smooth engine operation.
- Reduces Mechanical Stress: Helps prevent unwanted movement that may damage cylinder heads, cylinders or associated components.
- Protects Engine Reliability: Reduces the risk of further damage caused by a loose or improperly secured cylinder head.
- Replaces Damaged Threads: Restores reliable fastening where the original stud is corroded, stripped or otherwise unsuitable for reuse.
- Original Equipment-Style Fitment: Designed to match the corresponding Porsche engine fastening arrangement.
- Suitable for Engine Rebuilds: Ideal when replacing worn engine fastening components during a complete rebuild.
- Supports Top-End Overhauls: Provides the correct replacement component when cylinder heads are removed for servicing.
- Helps Prevent Expensive Engine Repairs: Addressing damaged cylinder head hardware promptly may prevent further mechanical damage.
- Maintains Classic Porsche Originality: Preserves the original fastening arrangement used on the applicable air-cooled four-cylinder engines.
Although the cylinder head stud is a relatively small component, it performs a critical function in maintaining the structural integrity of the engine.
A broken or damaged stud may reduce the clamping force holding the cylinder head in place, potentially allowing combustion gases to escape and affecting engine compression.
Continued operation with a loose or incorrectly secured cylinder head can increase thermal and mechanical stress on surrounding components, leading to further damage.
Replacing a defective stud with an OE MATCH component helps restore the specified fastening arrangement and supports dependable engine performance.
During engine rebuilding, all cylinder head studs should be inspected carefully. Where multiple studs show signs of corrosion, thread damage or fatigue, replacing the affected fasteners may be advisable to maintain consistent assembly integrity.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
53901118
The product you are viewing cross references to these numbers
- 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)
- 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
This OE Match cylinder head stud is a replacement engine fastening stud for Porsche 911, 964, and 993 models from 1965 to 1998. It is designed to match the original-style fitment and function, helping secure the cylinder head and cylinder assembly correctly to the engine crankcase.
Sold individually, Normally 24 studs per engine
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
This product supersedes Porsche's old part numbers:
- 99310117051
Diagram Ref No 2.
The cylinder head stud provides the clamping force needed to hold the cylinder head, cylinder barrel, and engine case together. Correct head stud tension is essential for maintaining combustion sealing, cylinder stability, and reliable air-cooled engine operation.
Functions
• Secures the cylinder head and cylinder assembly to the engine case
• Provides correct clamping force for combustion sealing
• Supports cylinder and head alignment
• Helps maintain reliable engine sealing under heat and load
• Replaces corroded, stretched, broken, or damaged original studs
• Suitable for engine rebuilds, top-end repairs, and head stud replacement
• OE Match replacement for classic Porsche air-cooled engine repair
Why Replace This Part?
Cylinder head studs are exposed to high combustion forces, heat cycling, corrosion, vibration, and long-term engine load. Over time, studs can corrode, stretch, weaken, seize, or break. A damaged or broken head stud may cause compression leakage, oil seepage, cylinder head movement, exhaust leakage, poor running, or engine noise. Replacing worn or failed studs helps restore proper engine clamping and long-term reliability.
When to Replace This Part
• A cylinder head stud is broken, corroded, stretched, or damaged
• The engine has compression leakage or cylinder head sealing issues
• Oil seepage or combustion leakage is present around the cylinder/head area
• The engine is being rebuilt or overhauled
• The cylinder heads or barrels have been removed
• Existing studs are seized, heavily corroded, or unsuitable for reuse
• Preventative replacement is being carried out during top-end service.
Where it fits on the car
This cylinder head stud fits within the engine crankcase and extends through the cylinder barrel and cylinder head assembly. It forms part of the engine’s main cylinder/head fastening system and should be installed according to the factory engine layout and torque procedure.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
- 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)
- 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
Dilavar engine head studs are specialized fasteners used in the engines of certain Porsche models, especially air-cooled engines (like the 911). They are made from a proprietary alloy called Dilavar, which is designed to address specific thermal expansion and durability challenges in high-performance engines.
Price is each. Normally 24 studs per engine.
Fits:
Porsche 911 1965 - 1989
Porsche 964 1989 - 1994
Porsche 993 1994 - 1998
Diagram Ref No 2.
This product supersedes Porsche's old part numbers:
- 99310117051
Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case. These latest Dilavar steel head studs have a thermal expansion rate of approximately the same as the alloy case.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
- 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)
- 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 996 GT3 MKII 2003>>
- Porsche 997 MK1 TURBO 2007-09
- Porsche 997 MK1 GT3 / GT3 RS 2007-09
- Porsche 997 MK1 GT2 2007-09
- Porsche 914 (1970-1976)
Sold each.
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1995-98
Porsche 996 Turbo 2001-05
Porsche 996 GT3 3.6L 1999-05
Porsche 997.1 Turbo 2007-09
Porsche 997 GT3 3.6L 2006-09
Porsche 914-6 1970-76
Click 'Zoom in' for large parts diagram.
Diagram ref no 4
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90006010601
The product you are viewing cross references to these numbers
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 914 (1970-1976)
24 per engine. Price is for each.
Fits:
Porsche 911 1965-73
(Not 1973 2.7L Carrera)
Porsche 914-6 1970-72
Diagram ref No 5
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90110117203
The product you are viewing cross references to these numbers
-
Crankcase 911 1965-69 101-05
-
crankcase 912 1965-69 101-10
-
cylinder head, cylinder with piston 911 1965-69 103-00
-
cylinder head, cylinder with piston 912 1965-69 103-05
-
chain case, camshaft housing 911 1965-69 103-10
-
carburettor system with - SOLEX 40 PI-1 - for 911 UPTO 1968 107-06
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injection system cylinder head and injection pump for 911 E/S 1969 onwards 107-20
-
vacuum system for clutch release for sportomatic for 911 L/S/TU upto 1968 and 911 T 1969 ONWARDS 107-30
-
replacement transmission, transmission case, chilled casting 911 1965-69 302-00
-
converter and converter housing sportomatic 911 1965-69 306-00
-
transmission case sportomatic 911 1965-69 307-00
OEMatch Engine Bolts / Studs — Durability, Sealing, Performance
Engine bolts and studs are small but essential fasteners that secure cylinder heads, crankcases, connecting rods and manifolds on Porsche models. They maintain sealing, alignment and torque integrity during servicing, rebuilds and performance work; inspect fasteners for stretch, corrosion and thread damage during service.
OE (Original Equipment) refers to parts matching original specifications for the engine bolts / studs and may be supplied by alternative manufacturers. Aftermarket parts offer alternative options, sometimes with enhanced features or better value. OEMatch supplies non-OEM engine bolts / studs engineered as direct-fit alternatives to OEM parts, made to original-spec dimensions and tolerances for Porsche models.
- Consistent clamping force and torque retention to preserve seals and clearances
- High fatigue resistance to resist loosening under repeated torque cycles
- Improved corrosion protection with suitable coatings or materials
- Metal fatigue or stretching from repeated torque applications
- Corrosion and oxidation, especially in high-heat or humid conditions
- Incorrect torque, over-tightening or under-torquing during installation
- Thread wear or damage from debris, cross-threading or improper handling
- Direct-fit replacements engineered to match original dimensions and tolerances for Porsche models
- Available in high-tensile and corrosion-resistant finishes to suit application requirements
- Precision threads for repeatable installation and reliable torque control
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Intermediate shaft (IMS)
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Oil System Parts
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Fuel System Parts
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Gaskets & Sets
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Belts / Tensioners / Rollers
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Chains & Tensioners
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