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Exhaust Nuts / Bolts / Studs
By OE Match
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
The OE Match Exhaust Lock Nut for Bolt is a high-quality replacement fastening component designed to securely retain exhaust system bolts in high-temperature operating environments. Manufactured to OE specifications for thread accuracy, strength and heat resistance, this self-locking nut helps maintain secure exhaust connections while resisting loosening caused by heat cycles, vibration and engine movement.
Fits:
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
Diagram Ref No 25
Manufactured from high-strength, corrosion-resistant steel with a durable heat-resistant finish, the lock nut is specifically engineered for use within Porsche exhaust systems. Its self-locking design provides reliable clamping force, helping to maintain leak-free exhaust joints and ensuring long-term reliability of exhaust manifold, catalytic converter, silencer and pipework connections where applicable.
What This Product Does:
- Securely fastens exhaust system components together.
- Maintains consistent clamping force under high temperatures.
- Resists loosening caused by vibration and thermal expansion.
- Helps prevent exhaust gas leaks.
- Supports correct exhaust alignment.
- Provides reliable fastening for exhaust repairs and installations.
- Replaces worn, corroded or damaged original lock nuts.
- Forms an essential part of the exhaust mounting system.
Symptoms Of Wear Or Failure:
- Loose exhaust components.
- Exhaust blowing or gas leaks.
- Rattling or vibrating exhaust system.
- Corroded or seized fasteners.
- Damaged or stripped threads.
- Loss of locking capability.
- Broken or missing fixing hardware.
- Difficulty maintaining correct exhaust alignment.
- Increased exhaust noise.
- Visible rust or deterioration of the fastening hardware.
Why Replacement Matters:
- Exhaust fasteners operate in one of the harshest environments on the vehicle, where they are exposed to extreme temperatures, rapid heating and cooling cycles, moisture, road salt and constant vibration. Over time, conventional fasteners can corrode, seize or lose their clamping force, allowing exhaust joints to loosen.
- A worn or damaged lock nut can result in exhaust leaks, excessive movement and increased stress on surrounding exhaust components. Loose exhaust connections may also generate unwanted noise, reduce exhaust efficiency and accelerate wear of gaskets and mounting hardware.
- Replacing exhaust lock nuts whenever exhaust components are serviced helps ensure secure, long-lasting connections and reliable sealing. An OE Match replacement provides factory-style fitment, high-strength construction and excellent resistance to heat and corrosion, helping maintain the durability, performance and reliability of your Porsche's exhaust system.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99908405202
The product you are viewing cross references to these numbers
- 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) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
This exhaust manifold stud is a high-strength threaded stud used to secure the exhaust manifold (heat exchanger) to the cylinder head on classic air-cooled Porsche 911, Turbo (930), and 964 Turbo models.
Sold individually, 12 required per engine.
Fits:
Porsche 911 Turbo (930) 1978 - 1989
Porsche 911 Carrera 3.2L 1984 - 1989
Porsche 964 Turbo 3.3L 1991 - 1992
Porsche 964 Turbo 3.6L 1993 - 1994
Diagram ref. no. 5A
The exhaust manifold stud forms a critical fastening point that holds the exhaust manifold (or heat exchanger) firmly to the engine’s cylinder head. It ensures the exhaust system components remain tightly seated under heat, vibration, and thermal cycling, preventing exhaust leaks and preserving engine performance.
This stud’s threaded design enables secure engagement with corresponding nuts and manifold flanges. By maintaining proper clamping force, it helps support the manifold gasket and metal mating surfaces, sustaining a leak-free joint under extreme exhaust temperatures and repeated heating/cooling cycles.
Exhaust studs undergo intense heat and stress, which over time can lead to stretching, thread wear, or breakage. A compromised stud can allow exhaust leaks, reduce engine efficiency, and make future removal of the manifold difficult. Replacing them restores correct fit, proper torque retention, and long-term exhaust system reliability.
When to replace:
• Studs show corrosion, thread wear, or distortion
• One or more studs have broken during removal
• Exhaust leak noises at the manifold flange
• During manifold gasket replacement
• Preventive renewal during engine or exhaust overhaul
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99906223903
The product you are viewing cross references to these numbers
-
cylinder head 964 1989-94 103-00
-
turbocharging oil supply for turbocharger 964 TURBO M30.69 and M64.50 1991-94 107-40
-
exhaust system: muffler, catalytic converter 964 M64.01/02/03 1989-94 202-00
-
exhaust system: heat exchanger 964 M64.01/02/03 1989-94 202-05
-
exhaust system 964 TURBO M30.69 and M64.50 1991-94 202-15
OEMatch Exhaust Nuts / Bolts / Studs — Flow, Response, Refinement
OEMatch Exhaust Nuts / Bolts / Studs provide robust fasteners for Porsche models to help maintain secure joints and consistent exhaust flow during routine use and higher-load driving. Many owners search for genuine or OEM exhaust nuts, bolts and studs; these are direct-fit alternatives designed to match the original form, fit and function. These fasteners are selected for heat and vibration resistance while keeping routine servicing straightforward.
Available Types
- Hex flange bolts for manifold and flange connections
- Threaded studs with matching nuts for high-temperature joints
- Corrosion-resistant nuts with locking washers and heat-resistant coatings
Understanding OEMatch Exhaust Nuts / Bolts / Studs
OEM (Original Equipment Manufacturer) parts are made by the same company that produced your Porsche’s original exhaust nuts, bolts and studs.
OE (Original Equipment) refers to parts matching original specifications for the exhaust nuts, bolts and studs and may be supplied by alternative manufacturers. Aftermarket parts offer alternative options, sometimes with enhanced features or better value. OEMatch supplies non-OEM exhaust nuts, bolts and studs engineered as direct-fit alternatives to OEM parts, made to original-spec dimensions and tolerances for Porsche models.
OEMatch also offers a wide selection of Porsche components, cataloguing over 4,000 individual part numbers and more than 8,700 cross-references while developing additional lines to support maintenance and repair across Porsche generations.
Benefits Include
- Restores and maintains secure exhaust joints to prevent leaks
- Reduces vibration, rattling and movement under thermal cycling
- Improves serviceability with standard thread sizes and corrosion-resistant finishes
Why Exhaust Nuts / Bolts / Studs Wear and Fail
- Corrosion from moisture, road salt and exhaust condensates
- Thermal expansion and contraction leading to loosening or fatigue
- Over-torquing, cross-threading or mechanical damage during servicing
The Importance of Replacing with OEMatch Exhaust Nuts / Bolts / Studs
OEMatch exhaust components are compatible replacements engineered to original-spec dimensions and tolerances — a practical option when genuine or OEM parts are unavailable. Correct fasteners preserve exhaust sealing, maintain correct alignment of manifolds and pipes, and help protect sensors and downstream emissions equipment. Replacing degraded hardware reduces the risk of leaks, unwanted noise and component damage while supporting reliable performance for Porsche models.
Advantages
- Materials and coatings selected for heat and corrosion resistance
- Thread profiles and lengths aligned to original specifications where applicable
- Standard sizes and finishes to simplify maintenance and reduce the risk of seizing
