Acura NSX 1990-2005 Exhaust System Bolt Torque Specifications
This page provides detailed torque specifications for exhaust system bolts on the 1990-2005 Acura NSX, including manifold, downpipe, and cat-back connections.
Important Information
Safety guidelines and reference information for proper torque application
Safety First
- Always verify torque specifications with your vehicle's factory service manual
- Use properly calibrated torque wrenches
- Replace all torque-to-yield (TTY) bolts - they are single-use only
- When in doubt, consult a professional mechanic
Quick Reference Guide
Quick Reference Guide
Common Torque Patterns
Star Pattern
Used for wheels and other circular bolt patterns
Cross Pattern
Used for gaskets and cover plates
Sequential Pattern
Used for head bolts and other critical components
Common Mistakes to Avoid
Common Mistakes to Avoid
Over-tightening
Exceeding the specified torque value can stretch or break fasteners, damage threads, or crack components.
Always use a calibrated torque wrench and follow specifications exactly.
Incorrect Torque Sequence
Tightening bolts in the wrong order can cause uneven pressure distribution and potential leaks or damage.
Follow the manufacturer's specified torque sequence pattern.
Dirty Threads
Dirt, rust, or old thread locker can affect torque readings and proper fastener tension.
Clean and inspect all threads before assembly. Use new thread locker if specified.
Reusing TTY Bolts
Torque-to-yield bolts are designed to stretch and must not be reused.
Always replace TTY bolts with new ones. They are single-use only.
Dry vs. Lubricated
Not accounting for whether torque specs are for dry or lubricated fasteners can lead to incorrect tension.
Check if specs are for dry or lubricated threads. Use specified lubricant when required.
Recommended Tools
Recommended Tools
Torque Wrench (1/4" Drive)
Torque Wrench (3/8" Drive)
Torque Wrench (1/2" Drive)
Angle Gauge
Torque Wrench Care
- Calibrate annually or after 5,000 clicks
- Store at lowest setting
- Keep clean and lubricated
Search Specifications
Search by component name, bolt size, or description
Torque Calculator
Convert between different torque units
Exhaust Manifold
Torque specifications for the exhaust manifold and header components.
1 Exhaust Manifold/Headers to Cylinder Head Bolts
M8 x 1.25
Exhaust Manifold/Headers to Cylinder Head Bolts
M8 x 1.25Torque Value
Important Notes
2 Exhaust Pipe to Exhaust Manifold/Headers Bolts
M8 x 1.25
Exhaust Pipe to Exhaust Manifold/Headers Bolts
M8 x 1.25Torque Value
Important Notes
Exhaust System
Torque specifications for exhaust piping, catalytic converter, and muffler components.
1 Catalytic Converter to Exhaust Pipe Bolts
M8 x 1.25
Catalytic Converter to Exhaust Pipe Bolts
M8 x 1.25Torque Value
Important Notes
2 Muffler to Exhaust Pipe Bolts
M8 x 1.25
Muffler to Exhaust Pipe Bolts
M8 x 1.25Torque Value
Important Notes
3 Exhaust Pipe Flange Bolts (M8)
M8 x 1.25
Exhaust Pipe Flange Bolts (M8)
M8 x 1.25Torque Value
Important Notes
4 Exhaust Pipe Flange Bolts (M10)
M10 x 1.5
Exhaust Pipe Flange Bolts (M10)
M10 x 1.5Torque Value
Important Notes
Exhaust Mounting
Torque specifications for exhaust hangers, oxygen sensors and heatshields.
1 Exhaust Hanger Bolts
M8 x 1.25
Exhaust Hanger Bolts
M8 x 1.25Torque Value
Important Notes
2 Oxygen Sensor (O2 Sensor)
M18 x 1.5
Oxygen Sensor (O2 Sensor)
M18 x 1.5Torque Value
Important Notes
3 Exhaust Heat Shield Bolts
M6 x 1.0
Exhaust Heat Shield Bolts
M6 x 1.0Torque Value
Important Notes
4 Exhaust System Clamps Torque
N/A
Exhaust System Clamps Torque
N/ATorque Value
Important Notes
Troubleshooting Guide
Common issues, diagnostic steps, and prevention guidelines
Common Issues
Bolt stretching, stripped threads, uneven torque patterns
Common Issues
Bolt stretching, stripped threads, uneven torque patterns
Loose Components
Symptoms:
- Rattling or vibration noises
- Visible movement in components
- Uneven panel gaps
Solutions:
- Clean threads and mounting surfaces
- Replace damaged fasteners
- Apply proper torque in sequence
- Use thread locker if specified
Stripped Fasteners
Symptoms:
- Unable to achieve proper torque
- Fastener spins freely
- Visible thread damage
Solutions:
- Use thread repair kit if appropriate
- Install thread insert (HeliCoil)
- Replace component if threaded hole is damaged
- Upgrade to higher grade fastener if recommended
Overtightened Components
Symptoms:
- Cracked or deformed parts
- Broken fasteners
- Compressed gaskets or seals
Solutions:
- Replace damaged components
- Use new fasteners
- Follow proper torque sequence
- Verify correct torque specifications
Diagnostic Steps
Visual inspection, torque verification, thread assessment
Diagnostic Steps
Visual inspection, torque verification, thread assessment
Visual Inspection
Inspect the affected area for any visible signs of damage or wear
- Check for cracks or deformation
- Look for signs of excessive wear
- Verify proper fastener installation
Torque Verification
Verify the torque applied to the fasteners
- Check the torque wrench calibration
- Verify the torque specification
- Compare the applied torque to the specification
Thread Assessment
Assess the condition of the threads
- Check for signs of thread damage
- Verify the thread type and size
- Check for proper thread engagement
Prevention Guidelines
Best practices, maintenance tips, tool care
Prevention Guidelines
Best practices, maintenance tips, tool care
Best Practices
- Always follow the recommended torque specification
- Use the correct type and size of fasteners
- Verify the torque wrench calibration regularly
Maintenance Tips
- Regularly inspect the affected area for signs of wear or damage
- Replace damaged or worn-out components promptly
- Keep the work area clean and organized
Tool Care
- Regularly clean and maintain the torque wrench
- Store the torque wrench in a dry and secure location
- Verify the torque wrench calibration before each use
Frequently Asked Questions
Find answers to common questions about torque specifications
Q1 Why is using the correct torque specification important for exhaust bolts?
Why is using the correct torque specification important for exhaust bolts?
Using the correct torque specification is crucial to prevent exhaust leaks, damage to the threads, and premature bolt failure. Under-tightening can lead to leaks and rattling, while over-tightening can stretch the bolts, damage threads in the flange or manifold, and even cause bolts to break.
Q2 What happens if I over-torque exhaust bolts?
What happens if I over-torque exhaust bolts?
Over-torquing can stretch or shear the bolts, leading to difficult removal or costly repairs. It can also crush the gasket, causing leaks or even damage to the exhaust manifold or pipe flanges. For example, a common scenario is stripping the threads on the manifold if you significantly exceed the torque spec.
Q3 What happens if I under-torque exhaust bolts?
What happens if I under-torque exhaust bolts?
Under-torquing will likely result in exhaust leaks and rattling, leading to decreased engine performance and increased cabin noise. Leaks can also allow dangerous exhaust fumes to enter the cabin. A loose exhaust bolt will vibrate and may even fall out completely if left unattended, for example during track day sessions.
Q4 Should I use anti-seize on exhaust bolts?
Should I use anti-seize on exhaust bolts?
Yes, it is highly recommended to apply a thin layer of high-temperature anti-seize compound to the threads of exhaust bolts. This will prevent the bolts from seizing due to heat and corrosion, making future removal much easier. Be careful to keep the anti-seize off the flange and gasket sealing areas.
Q5 What should I do if a bolt breaks during removal?
What should I do if a bolt breaks during removal?
If a bolt breaks, you will need to extract the broken portion. A stud extractor or left-handed drill bit may work. In some cases, professional help from a machine shop may be necessary. Always work slowly when removing old exhaust bolts.
Q6 Do I need new exhaust gaskets when reinstalling the exhaust?
Do I need new exhaust gaskets when reinstalling the exhaust?
Yes, always use new exhaust gaskets whenever the exhaust system is disassembled. Old gaskets are likely to be compressed and will not seal properly, leading to leaks. Failing to use new gaskets, even if they look ok, will typically result in exhaust leaks.
Environmental Considerations
Temperature, humidity, and seasonal effects on torque specifications
Temperature Effects
Includes: High Heat, Cold Weather, Thermal Cycling
Temperature Effects
Includes: High Heat, Cold Weather, Thermal Cycling
Temperature can significantly impact torque values and fastener behavior
Cold Weather
Effects:
- Increased material brittleness
- Higher torque required due to thread contraction
- Reduced thread lubricant effectiveness
Recommendations:
- Allow components to warm to room temperature when possible
- Consider using winter-grade thread lubricants
- Check torque values more frequently during winter months
Hot Weather
Effects:
- Thermal expansion of components
- Decreased friction in threads
- Accelerated lubricant breakdown
Recommendations:
- Check torque when components are at normal operating temperature
- Use temperature-resistant thread lockers
- Consider re-torquing after heat cycles
Humidity and Corrosion
Covers: Rust Prevention, Salt Exposure, Moisture Control
Humidity and Corrosion
Covers: Rust Prevention, Salt Exposure, Moisture Control
Moisture and corrosion can affect fastener integrity and torque values
High Humidity
Effects:
- Accelerated corrosion formation
- Reduced friction coefficient
- Potential thread seizing
Prevention:
- Use corrosion-resistant fasteners
- Apply appropriate anti-seize compounds
- Maintain proper protective coatings
Salt Exposure
Effects:
- Rapid corrosion development
- Thread damage
- Seized fasteners
Prevention:
- Regular underbody washing
- Use of sacrificial anodes where appropriate
- Application of protective coatings
Seasonal Maintenance
Spring, Summer, Fall, and Winter maintenance schedules
Seasonal Maintenance
Spring, Summer, Fall, and Winter maintenance schedules
Spring
- Inspect for winter damage
- Clean and protect exposed fasteners
- Check torque on critical components
Summer
- Monitor heat-affected components
- Check expansion-related loosening
- Inspect cooling system mounts
Fall
- Prepare for winter conditions
- Apply corrosion protection
- Verify all fasteners are properly torqued
Winter
- More frequent inspection of critical fasteners
- Check for salt damage
- Monitor suspension component torque
Related Resources
Tools, service procedures, and technical bulletins
Recommended Tools
Torque Wrench
A calibrated torque wrench is essential for accurately tightening exhaust bolts to the specified torque, preventing leaks and damage.
- 1/2 inch drive (recommended for exhaust components)
- Torque range of at least 10-80 ft-lbs
- Click-type or digital readout for accurate settings
Socket Set
A comprehensive socket set with various sizes is necessary to fit different bolt heads on the NSX exhaust system.
- Metric sizes ranging from 10mm to 17mm (common sizes)
- Deep sockets for reaching recessed bolts
- 6-point sockets for better grip and reduced rounding of bolt heads
Universal Joint
A universal joint adapter will provide the flexibility to reach bolts that are at an odd angle.
- 1/2 inch drive (same drive as torque wrench)
- Durable construction
- Smooth operation
Extension Bars
Extension bars will help reach bolts that are farther away.
- 1/2 inch drive (same drive as torque wrench)
- Varying lengths to help with accessibility
- Durable construction
Service Procedures
Exhaust Manifold Bolt Torque Procedure
This procedure outlines the steps for correctly torquing the exhaust manifold bolts on a 1990-2005 Acura NSX.
- Locate the exhaust manifold bolts connecting the exhaust manifold to the cylinder head.
- Using the correct size socket, apply a light coating of anti-seize lubricant to the threads of the bolts. This prevents future seizing and corrosion.
- Hand-tighten the exhaust manifold bolts in a star or criss-cross pattern to ensure even distribution of pressure.
- Set the torque wrench to 22 ft-lbs (30 Nm).
- Torque the bolts in the same star or criss-cross pattern to 22 ft-lbs (30 Nm).
- Recheck the torque on all bolts after tightening all of them to ensure correct values.
Exhaust Pipe Connection Bolt Torque Procedure
This procedure outlines the steps for correctly torquing the exhaust pipe connection bolts on a 1990-2005 Acura NSX.
- Locate the bolts connecting the exhaust pipes (front pipe to manifold, mid-pipe to front pipe, etc.).
- Using the correct size socket, apply a light coating of anti-seize lubricant to the threads of the bolts. This prevents future seizing and corrosion.
- Hand-tighten the bolts to ensure even seating.
- Set the torque wrench to 33 ft-lbs (45 Nm).
- Torque the bolts to 33 ft-lbs (45 Nm).
- Recheck the torque on all bolts after tightening all of them to ensure correct values.
Exhaust Flange Bolt Torque Procedure
This procedure outlines the steps for correctly torquing the exhaust flange bolts on a 1990-2005 Acura NSX.
- Locate the bolts connecting exhaust flanges (connecting pipes).
- Using the correct size socket, apply a light coating of anti-seize lubricant to the threads of the bolts. This prevents future seizing and corrosion.
- Hand-tighten the bolts to ensure even seating of the flanges.
- Set the torque wrench to 16 ft-lbs (22 Nm).
- Torque the bolts to 16 ft-lbs (22 Nm).
- Recheck the torque on all bolts after tightening all of them to ensure correct values.
Technical Service Bulletins
Exhaust Manifold Gasket Leakage
1999-03-15Some 1991-1999 NSX models may experience exhaust leaks at the manifold due to gasket wear. Retorquing may temporarily alleviate the issue but a replacement may be required.
Resolution: Inspect the exhaust manifold gaskets for signs of damage or wear. Replace with genuine Acura gaskets and torque bolts to the specified 22 ft-lbs (30 Nm). Use new studs and nuts if necessary.
Exhaust System Noise Complaints
2002-07-20A number of 2000-2003 NSX owners have reported excessive noise from the exhaust system at higher RPMs. This may be caused by loosening bolts or damaged flanges.
Resolution: Inspect the entire exhaust system for loosen bolts and damaged flange. Torque all exhaust bolts to their correct specification, Replace any damaged parts as necessary.
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Technical Information
- All specifications, including torque values, fluid capacities, and maintenance procedures, should be verified against your vehicle's factory service manual.
- Vehicle specifications and procedures may vary by model year, trim level, and region.
- Always follow the manufacturer's recommended procedures and safety precautions.
- Working on vehicles can be dangerous. Always take proper safety precautions and use appropriate safety equipment.
- If you're unsure about any procedure, consult a qualified professional mechanic.