Exhaust hex nut in Titanium for heat exchanger. Porsche 911 / 964 / 993  ❭  99908500103T

Exhaust Bolt M8x40
Sold each

Ensure secure and reliable exhaust system installation with this M8x40 Exhaust Bolt, suitable for a wide variety of Porsche exhaust applications. Used throughout numerous exhaust assemblies including heat exchangers, manifolds, cross pipes, silencers, mounting brackets and associated exhaust components, this fastener plays a critical role in maintaining the integrity and alignment of the exhaust system.

Fits:

• 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

Diagram ref no 9

Exhaust bolts are subjected to extreme operating conditions including heat, vibration, moisture and road contamination. Over time, original fasteners can corrode, weaken, seize or become damaged during maintenance and removal. Replacing worn hardware helps ensure proper clamping force, leak-free operation and long-term exhaust system reliability.

Whether carrying out routine maintenance, replacing exhaust components or undertaking a full restoration project, fitting new exhaust hardware is considered best practice for achieving professional results.

What Does an Exhaust Bolt Do?

An exhaust bolt is designed to securely fasten exhaust components together while maintaining the clamping force required for proper gasket sealing and component alignment.

A correctly installed exhaust bolt helps provide:

• Secure exhaust system assembly
• Proper gasket compression
• Reduced risk of exhaust leaks
• Correct component alignment
• Improved system reliability
• Resistance to vibration-related loosening
• Safe long-term operation

Although small, exhaust fasteners are essential to the overall performance and durability of the exhaust system.

Symptoms of Wear or Failure

Exhaust hardware operates in one of the harshest environments on the vehicle. Continuous heat cycles and exposure to the elements can cause fasteners to deteriorate over time.

Common signs of worn or damaged exhaust bolts include:

• Corrosion or rust build-up
• Seized or stripped threads
• Broken bolts during removal
• Loose exhaust components
• Exhaust leaks around joints
• Excessive exhaust vibration
• Rattling exhaust noises
• Inability to achieve correct torque settings
• Visible deterioration of fastener surfaces

Failing exhaust hardware can compromise the effectiveness of gaskets and lead to premature exhaust system wear.

Why Replacement Matters

Replacing ageing exhaust bolts helps ensure reliable fastening and proper exhaust system sealing.

Benefits include:

• Improved exhaust system security
• Reduced risk of exhaust leaks
• Better gasket performance
• Easier future maintenance
• Improved component alignment
• Enhanced reliability
• Professional-quality repairs
• Protection of exhaust system components

Whenever exhaust components are removed, replacing worn fasteners helps prevent future issues and ensures long-term durability.

Features & Benefits

• M8 x 40mm exhaust bolt
• Suitable for various Porsche exhaust applications
• High-strength exhaust system fastener
• Helps maintain proper exhaust sealing
• Supports secure component installation
• Resistant to exhaust system vibration
• Ideal for repairs, maintenance and restoration projects
• Direct replacement for worn or corroded hardware

Complete your Porsche exhaust repair correctly with quality M8x40 Exhaust Fasteners from Design911

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

90007428203

The product you are viewing cross references to these numbers

M8 Exhaust Nut - M8
Sold each and used throughout 

The Porsche M8 Exhaust Nut is a high-quality replacement fastener used in various positions across Porsche exhaust systems. Designed to secure exhaust components such as manifolds, heat exchangers, silencers, brackets and connecting flanges, this nut helps maintain correct clamping force and reliable exhaust sealing.

Fits:

• 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

Exhaust nuts operate in extremely harsh conditions, exposed to heat cycles, vibration, moisture, road salt and corrosion. Over time, original nuts can seize, round off, strip or weaken, making removal difficult and reducing their ability to hold exhaust components securely.

Replacing worn exhaust hardware during servicing or restoration helps ensure a secure, leak-free and professional exhaust installation.

What Does an Exhaust Nut Do?

An exhaust nut fastens exhaust components to studs or bolts, holding joints tightly together and helping maintain gasket compression.

A correctly fitted exhaust nut helps provide:

• Secure exhaust component mounting
• Proper gasket sealing
• Reduced risk of exhaust leaks
• Correct exhaust alignment
• Improved resistance to vibration
• Long-term exhaust system reliability

Symptoms of Wear or Failure

Common signs that an exhaust nut may need replacement include:

• Rust or heavy corrosion
• Rounded or damaged edges
• Stripped threads
• Seized nut during removal
• Loose exhaust joints
• Exhaust blowing noises
• Rattling or vibration from the exhaust
• Soot marks around exhaust flanges
• Inability to tighten to the correct torque

Why Replacement Matters

Replacing worn or corroded exhaust nuts helps prevent exhaust leaks, loose components and future repair difficulties.

Benefits include:

• Restores secure exhaust fastening
• Helps prevent exhaust leaks
• Improves gasket sealing
• Reduces vibration and rattles
• Makes future maintenance easier
• Supports reliable exhaust repairs
• Protects surrounding exhaust components
• Improves restoration quality       

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

90091009701

The product you are viewing cross references to these numbers

Exhaust hexnut for heat exchanger
3 per heat exchanger.



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)

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99908500103

The product you are viewing cross references to these numbers