Audi Audi S5 2017-present Exhaust System Bolt Torque Specifications
Detailed torque specifications for all exhaust system bolts on the 2017-Present Audi S5 (B9 generation). Includes downpipe, mid-pipe, and rear muffler bolt torque values.
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 components related to the exhaust manifold, including connections to the cylinder head and downpipe.
1 Exhaust Manifold to Cylinder Head Bolts
M8 x 1.25
Exhaust Manifold to Cylinder Head Bolts
M8 x 1.25Torque Value
Important Notes
2 Exhaust Manifold to Downpipe/Catalytic Converter Bolts/Nuts
M10 x 1.5
Exhaust Manifold to Downpipe/Catalytic Converter Bolts/Nuts
M10 x 1.5Torque Value
Important Notes
Downpipe Midpipe
Torque specifications for components related to the downpipe and mid-pipe of the exhaust system.
1 Downpipe to Exhaust Mid-Pipe Bolts/Nuts
M10 x 1.5
Downpipe to Exhaust Mid-Pipe Bolts/Nuts
M10 x 1.5Torque Value
Important Notes
Midpipe Muffler
Torque specifications for components connecting the mid-pipe to the muffler and rear exhaust section.
1 Mid-Pipe to Muffler/Rear Section Bolts/Nuts (Flange Connection)
M8 x 1.25
Mid-Pipe to Muffler/Rear Section Bolts/Nuts (Flange Connection)
M8 x 1.25Torque Value
Important Notes
Exhaust Hangers
Torque specifications for bolts securing the exhaust hangers to the chassis.
1 Exhaust Hanger Bracket Bolts (Chassis to Hanger)
M8 x 1.25
Exhaust Hanger Bracket Bolts (Chassis to Hanger)
M8 x 1.25Torque Value
Important Notes
Exhaust Clamps
Torque specifications for exhaust band clamps used in certain exhaust system connections.
1 Exhaust Clamp Bolts (Band Clamps)
M8 x 1.25
Exhaust Clamp Bolts (Band Clamps)
M8 x 1.25Torque Value
Important Notes
Oxygen Sensor
Torque specifications for oxygen sensors installed into the exhaust system.
1 Oxygen Sensor (O2 Sensor)
22mm Thread
Oxygen Sensor (O2 Sensor)
22mm ThreadTorque Value
Important Notes
Exhaust Shields
Torque specifications for bolts securing the heat shields around the exhaust system.
1 Exhaust System Shield Bolts (Heat Shields)
M6 x 1.0
Exhaust System Shield Bolts (Heat Shields)
M6 x 1.0Torque 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 are correct torque specifications important for exhaust bolts?
Why are correct torque specifications important for exhaust bolts?
Correct torque ensures a proper seal between exhaust components, preventing leaks and exhaust noise. Over-tightening can stretch or break bolts, while under-tightening can lead to leaks and vibrations. For example, if you don't properly torque the bolts connecting the downpipe to the mid-pipe, you may experience exhaust leaks and potentially sensor errors. Always use a calibrated torque wrench.
Q2 What happens if I over-tighten exhaust bolts?
What happens if I over-tighten exhaust bolts?
Over-tightening exhaust bolts can damage the bolts themselves (stripping threads, elongation, or fracture), the exhaust flanges (warping, cracking), or the exhaust gaskets (crushing). This can lead to exhaust leaks, difficulty in future removal, and in extreme cases, necessitate costly repairs or replacement of components. For example, overtightening the bolts at the exhaust manifold could warp the flange and require a manifold replacement.
Q3 Can I reuse exhaust bolts?
Can I reuse exhaust bolts?
It is generally recommended to replace exhaust bolts, especially those used in high-temperature areas, after they have been torqued once. The extreme heat can degrade the bolts and cause them to stretch, leading to inaccurate torque application upon reuse. While you *can* reuse bolts in some situations, reusing fasteners that are clearly damaged, or those used in high stress areas, is not recommended. For example, bolts connecting the exhaust to the catalytic converter should almost always be replaced.
Q4 Should I use anti-seize on exhaust bolts?
Should I use anti-seize on exhaust bolts?
Using a high-temperature anti-seize compound on exhaust bolts is advisable, especially in areas prone to rust and corrosion. It can prevent bolts from seizing and make future removal much easier. However, be sure to adjust the torque specification when using lubricant, as it will reduce friction and increase clamp load at the same torque. Consult your torque wrench instructions. For example, anti-seize on the flange bolts near the catalytic converter will ease future removal.
Q5 How often should I check the torque on exhaust bolts?
How often should I check the torque on exhaust bolts?
It's a good practice to re-check the torque on exhaust bolts after a few heat cycles, generally after driving a hundred miles or so after installation. Metal expands and contracts with temperature changes, and bolts can sometimes loosen during initial driving. A periodic check can prevent leaks. For example, after installing a new aftermarket exhaust system on your S5, re-torque all the connections after 100 miles to ensure a proper seal.
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 (1/2" Drive)
A calibrated torque wrench is essential for accurately tightening exhaust bolts to the manufacturer's specified torque.
- Adjustable torque settings
- Click-type mechanism for accurate readings
Torque Wrench (3/8" Drive)
A smaller calibrated torque wrench for exhaust components that require a lower torque spec.
- Adjustable torque settings
- Click-type mechanism for accurate readings
Socket Set (Metric)
A set of metric sockets with appropriate sizes for exhaust bolts.
- Variety of sizes
- Durable construction
Extension Bars
Extension bars help reach recessed or difficult-to-access exhaust bolts.
- Various lengths available
- Secure connection
Universal Joint
A universal joint allows for torque application at an angle when direct access is not possible.
- Flexible movement
- Durable construction
Service Procedures
Exhaust Manifold to Cylinder Head Bolt Torque
Procedure for tightening the exhaust manifold to the cylinder head bolts on a 2017-Present Audi S5
- Locate the exhaust manifold bolts.
- Using the appropriate socket, start all bolts by hand.
- Using a 3/8" drive torque wrench, torque bolts to 25 Nm in a criss cross pattern.
- Recheck torque after 5-10 minutes.
Downpipe to Exhaust Manifold Bolt Torque
Procedure for tightening the downpipe to exhaust manifold bolts on a 2017-Present Audi S5
- Locate the downpipe bolts.
- Using the appropriate socket, start all bolts by hand.
- Using a 1/2" drive torque wrench, torque bolts to 40 Nm in a criss cross pattern.
- Recheck torque after 5-10 minutes.
Cat-Back Exhaust Bolt Torque
Procedure for tightening the bolts of the cat-back exhaust system on a 2017-Present Audi S5
- Locate all cat-back system bolts.
- Using the appropriate socket, start all bolts by hand.
- Using a 1/2" drive torque wrench, torque bolts to 40 Nm in a criss cross pattern.
- Recheck torque after 5-10 minutes.
Technical Service Bulletins
Exhaust Bolt Loosening After Thermal Cycling
2020-07-15Some 2017-2020 Audi S5 models have reported exhaust bolt loosening due to thermal expansion and contraction of the metal. This can lead to exhaust leaks.
Resolution: Apply a medium-strength threadlocker to the bolts and torque them to the specified torque. It is also recommended that torque is rechecked after 1000-2000 miles and again at regular service intervals.
Corrosion of Exhaust Flange Bolts
2021-11-01Reports of corrosion on exhaust flange bolts, particularly in regions with road salt use, can affect proper torque and clamping force. A visual inspection is advised.
Resolution: Replace corroded bolts with new OEM hardware and use a copper-based anti-seize lubricant. Torque bolts to specified values.
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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.