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Engine Bolts / Studs
By OE Match
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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)
Information
Cylinder head nut washer (Head nut washer)
This washer is used under the cylinder head nuts on Porsche 911 engines (1978–1989). It’s a precision washer made to the same style and dimensions as the original, helping the head nut seat correctly against the engine hardware.
Price is for each, 24 required per engine.
Fits:
Porsche 911 1978 - 1989
Diagram ref no 16
The washer spreads the clamping load from the head nut, helping maintain consistent torque retention and protecting mating surfaces from damage caused by concentrated pressure.
• It’s supplied per washer (price is for each) and 24 washers are required per engine.
It provides a stable, even load surface beneath each head nut, supporting correct tightening and helping the cylinder head fastening system maintain consistent clamp force over time - especially important on engines that see repeated thermal expansion and contraction.
• Distributes head nut load to reduce point-stress on components
• Helps maintain more consistent clamping force as the engine heat-cycles
• Supports proper seating of the head nut for reliable assembly during rebuilds
Old washers can become corroded, deformed, or marked from previous torque cycles. Reusing tired hardware can affect how evenly the head nuts clamp, which can compromise long-term sealing and reliability. Fresh washers help restore proper seating and load distribution during rebuild work.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903109101
The product you are viewing cross references to these numbers
This washer is used under the cylinder head nuts on Porsche 911 engines (1978–1989). It’s a precision washer made to the same style and dimensions as the original, helping the head nut seat correctly against the engine hardware.
Price is for each, 24 required per engine.
Fits:
Porsche 911 1978 - 1989
Diagram ref no 16
The washer spreads the clamping load from the head nut, helping maintain consistent torque retention and protecting mating surfaces from damage caused by concentrated pressure.
• It’s supplied per washer (price is for each) and 24 washers are required per engine.
It provides a stable, even load surface beneath each head nut, supporting correct tightening and helping the cylinder head fastening system maintain consistent clamp force over time - especially important on engines that see repeated thermal expansion and contraction.
• Distributes head nut load to reduce point-stress on components
• Helps maintain more consistent clamping force as the engine heat-cycles
• Supports proper seating of the head nut for reliable assembly during rebuilds
Old washers can become corroded, deformed, or marked from previous torque cycles. Reusing tired hardware can affect how evenly the head nuts clamp, which can compromise long-term sealing and reliability. Fresh washers help restore proper seating and load distribution during rebuild work.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99903109101
99903109101
The product you are viewing cross references to these numbers
Price: €3.45
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About Engine Bolts / Studs
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.
Understanding OEMatch Engine Bolts / Studs
OEM (Original Equipment Manufacturer) parts are made by the same company that produced your Porsche’s original engine bolts / studs.
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.
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.
Engine fasteners must deliver consistent clamping force while resisting stretching, vibration and corrosion. They secure critical assemblies and preserve internal clearances. OEMatch supplies a wide selection of Porsche components, from gaskets to suspension hardware, engine parts and interior trim. The catalogue includes thousands of part numbers and cross-references and is continually expanded to support maintenance and restoration.
Benefits Include- 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
The Importance of Replacing with OEMatch Engine Bolts / Studs
During an engine rebuild or major service, replacing aged or stressed bolts and studs helps maintain sealing, alignment and torque integrity. Correct-grade fasteners reduce the risk of leaks, distortion and mechanical failure and support reliable long-term operation on Porsche engines. Where critical, follow model-specific specifications for material grade and torque values.Advantages
- 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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