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Exhaust Nuts / 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 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) TURBO S 1994-97
OE Match exhaust hex nut designed as a direct-fit replacement fastener for the exhaust heat exchanger studs on classic Porsche 911 (1965–1998) engines. This hex nut secures the heat exchanger to the cylinder heads and exhaust studs, ensuring reliable fastening in the high-heat exhaust system environment.
Sold individually. 4, 5, or 6 required, depending on car model.
Fits:
Porsche 911 1965-89 (6 for both heat exchangers)
Porsche 964 Carrera 1989-94 (4 for both heat exchangers)
Porsche 993 Carrera 1994-98 (5 for both heat exchangers)
Porsche 993 Turbo 1994-98 (4 for both heat exchangers)
Diagram ref no 5
The hex nut is used in conjunction with the heat exchanger studs and exhaust system components to clamp the exhaust heat exchanger securely in place and maintain a sealed joint between mating parts.
The exhaust hex nut’s role may seem simple, but it’s critical to the integrity of the heat exchanger and exhaust assembly:
• Secures the heat exchanger studs to the engine block/exhaust flange
• Maintains clamp force under thermal cycling and vibration
• Helps prevent exhaust leaks at the heat exchanger interface
• Resists corrosion and heat exposure typical of exhaust temperatures.
Proper fastening ensures that the heat exchanger - which routes exhaust gasses away from the cylinders and towards the muffler system - remains sealed and aligned throughout engine operation.
Function
• Fastening: Threads onto the exhaust/heat exchanger stud to clamp components
• Retention: Holds joint integrity under vibration and thermal expansion
• Seal support: Helps maintain exhaust system seal and prevents leaks
• Heat resilience: Engineered from heat-resistant material for exhaust applications.
Worn, rusted, or missing hex nuts can lead to loose exhaust joints, exhaust leaks, poor performance, and increased noise.
Although small, exhaust hex nuts play a critical role in maintaining proper heat exchanger sealing and long-term exhaust durability. Over time, exposure to extreme heat and exhaust gases can cause nuts to corrode, seize, lose clamping force, or break during removal, leading to exhaust leaks and compromised sealing at the cylinder head. Replacing them with OE Match hex nuts restores secure fastening, helps prevent leaks, protects surrounding engine components from excess heat, and preserves overall exhaust performance.
Exhaust hex nuts should be replaced whenever the heat exchanger or exhaust system is removed, if the existing nuts are corroded, seized, rounded, or damaged, or when exhaust leaks are detected at the heat exchanger interface.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99908500103
The product you are viewing cross references to these numbers
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
This OE match exhaust lock nut is a direct replacement for the original Porsche component used in the exhaust system of the 964 generation 911.
Sold individually,
Fits:
Porsche 964 C2 / C4 1989 - 1994
Diagram ref no 10
This nut is commonly used on exhaust manifolds, heat exchangers, mufflers, and exhaust pipe connections, making it a critical piece of hardware for secure exhaust assembly.
This lock nut secures exhaust components together, ensuring a tight and reliable connection. Its locking design prevents loosening due to vibration and heat cycles, maintaining exhaust system integrity and preventing leaks.
Function
• Secures exhaust system components (manifold, pipes, muffler)
• Prevents loosening under high heat and vibration
• Maintains tight, leak-free exhaust connections
• Withstands extreme temperature conditions
• Allows reliable fastening with long-term durability
Exhaust lock nuts are exposed to extreme heat, corrosion, and constant vibration, which can cause them to seize, degrade, or lose their locking ability. Worn or incorrect fasteners can lead to exhaust leaks, loose components, or difficult disassembly. Replacing them ensures secure fastening and long-term reliability of the exhaust system.
When to replace
• During exhaust repairs or component replacement
• Nut is corroded, seized, or damaged
• Loss of locking function (nut loosens easily)
• Evidence of exhaust leaks at joints
• As part of preventative maintenance on older vehicles
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99908405202
The product you are viewing cross references to these numbers
-
turbocharging oil supply for turbocharger 964 TURBO M30.69 and M64.50 1991-94 107-40
-
power-steering pump 964 1989-94 108-00
-
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
-
suspension shock absorber strut 964 1989-94 402-00
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
