Exhaust nut. Porsche 911 1974-89  ❭  90091009701

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