Audi Audi S4 1991-1994 2.2L Engine Bolt Torque Specifications & Fastener Values
Audi Audi S4 1991-1994

Audi Audi S4 1991-1994 2.2L Engine Bolt Torque Specifications

Comprehensive guide to bolt torque specifications for the 2.2L inline-5 engine found in the 1991-1994 Audi S4, covering cylinder head, crankshaft, connecting rods, and other critical components.

Updated

Important Information

Safety guidelines and reference information for proper torque application

Quick Reference Guide
ft-lbs → Nm
× 1.356
ft-lbs → kg-m
× 0.138
Nm → ft-lbs
× 0.738
in-lbs → ft-lbs
× 0.083

Common Torque Patterns

Star Pattern

Used for wheels and other circular bolt patterns

Star Pattern torque pattern diagram showing proper bolt tightening sequence
Cross Pattern

Used for gaskets and cover plates

Cross Pattern torque pattern diagram showing proper bolt tightening sequence
Sequential Pattern

Used for head bolts and other critical components

Sequential Pattern torque pattern diagram showing proper bolt tightening sequence

Common Mistakes to Avoid

Over-tightening

Exceeding the specified torque value can stretch or break fasteners, damage threads, or crack components.

Prevention:

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.

Prevention:

Follow the manufacturer's specified torque sequence pattern.

Dirty Threads

Dirt, rust, or old thread locker can affect torque readings and proper fastener tension.

Prevention:

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.

Prevention:

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.

Prevention:

Check if specs are for dry or lubricated threads. Use specified lubricant when required.

Recommended Tools

Torque Wrench (1/4" Drive)

Range: 2-25 ft-lbs
Small fasteners, delicate components

Torque Wrench (3/8" Drive)

Range: 10-100 ft-lbs
Most common automotive fasteners

Torque Wrench (1/2" Drive)

Range: 30-250 ft-lbs
Large fasteners, wheels

Angle Gauge

Torque-to-yield (TTY) bolts

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

Cylinder Head

Specifications for bolts and nuts related to securing the cylinder head to the engine block. Proper torquing is critical for preventing leaks and maintaining engine compression.

1

Cylinder Head Bolts (Long)

M12 x 1.5
Important Notes
Torque-to-yield (TTY) bolt. Always replace after removal. Use a three-step torque process. First apply the initial torque, then rotate the bolt the first 90 degrees, and then the final 90 degrees. Torque sequence: Start in the center, and torque the bolts in a crisscross spiral pattern, working your way outwards.
2

Cylinder Head Bolts (Short)

M10 x 1.5
Important Notes
Torque-to-yield (TTY) bolt. Always replace after removal. Use a two-step torque process. First apply the initial torque, then rotate the bolt the first 90 degrees. Torque sequence: Start in the center, and torque the bolts in a crisscross spiral pattern, working your way outwards.

Intake Manifold

Specifications for fasteners attaching the intake manifold and throttle body to the cylinder head. Proper sealing is essential for optimal engine performance.

1

Intake Manifold Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Estimated value based on similar applications. Tighten evenly in a cross pattern.
2

Throttle Body Bolts

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Estimated value based on similar applications. Be careful not to over-tighten as this can damage the throttle body.

Exhaust Manifold

Specifications for bolts and nuts related to attaching the exhaust manifold to the cylinder head and downpipe. Critical for preventing exhaust leaks.

1

Exhaust Manifold to Cylinder Head Nuts/Studs

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Use a proper torque sequence (start from the center and work outwards). Check for proper mating before final torque. Ensure to replace any stretched studs
2

Exhaust Manifold to Downpipe Flange Bolts

M10 x 1.5
Torque Value
25 ft-lbs (34 N·m)
Important Notes
Estimated value. Check for proper alignment of exhaust components.

Valve Train

Torque specifications for fasteners securing the camshaft bearing caps and valve cover. Proper torque is essential for valve train alignment and oil sealing.

1

Camshaft Bearing Cap Bolts

M8 x 1.25
Torque Value
15 ft-lbs (20 N·m)
Important Notes
Estimated value. Torque in a cross-pattern, starting with the inner fasteners.
2

Valve Cover Bolts/Nuts

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Estimated value. Do not over-tighten as this can damage the valve cover gasket. Tighten in a cross pattern.

Engine Internals

Specifications for bolts securing internal engine components such as connecting rods, main bearings, oil pan, oil pump and flywheel/flexplate. Crucial for the structural integrity and performance of the engine.

1

Connecting Rod Bolts

M9 x 1.0
Important Notes
Torque-to-yield (TTY) bolt. Always replace after removal. First apply the initial torque, then rotate the bolt the first 90 degrees.
2

Main Bearing Cap Bolts

M10 x 1.5
Important Notes
Torque-to-yield (TTY) bolt. Always replace after removal. First apply the initial torque, then rotate the bolt the first 90 degrees. Tighten in a cross pattern starting with the middle fasteners, moving outwards.
3

Oil Pan Bolts

M6 x 1.0
Torque Value
15 ft-lbs (20 N·m)
Important Notes
Tighten evenly in a cross pattern. Do not over tighten.
4

Oil Pump Bolts

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Estimated value. Tighten evenly. Do not over-tighten.
5

Flywheel/Flexplate Bolts

M10 x 1.5
Important Notes
Torque-to-yield (TTY) bolt. Always replace after removal. First apply the initial torque, then rotate the bolt the first 90 degrees. Torque in a star pattern.

Timing Components

Specifications for fasteners securing timing components such as the timing belt tensioner and camshaft sprockets. Proper torque is essential for maintaining correct valve timing.

1

Timing Belt Tensioner Bolt

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Estimated value, ensure the tensioner is properly tensioned before final torque.
2

Camshaft Sprocket Bolts

M10 x 1.5
Torque Value
44 ft-lbs (60 N·m)
Important Notes
Estimated value. Ensure correct camshaft and timing alignment.

Engine Accessories

Specifications for bolts securing various engine accessories such as the alternator, power steering pump, AC compressor, and starter motor.

1

Alternator Mounting Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Estimated value. Tighten evenly.
2

Power Steering Pump Mounting Bolts

M8 x 1.25
Torque Value
15 ft-lbs (20 N·m)
Important Notes
Estimated value. Tighten evenly.
3

AC Compressor Mounting Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Estimated value. Tighten evenly.
4

Starter Motor Bolts

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Estimated value based on bolt size and industry standard. Tighten evenly.

Other Fasteners

Specifications for other critical fasteners such as the engine mount bolts. Proper torque is essential for structural integrity and vibration dampening.

1

Engine Mount Bolts

M12 x 1.75
Torque Value
45 ft-lbs (60 N·m)
Important Notes
Estimated value, verify size and application and use a torque value based on bolt size and application.

Troubleshooting Guide

Common issues, diagnostic steps, and prevention guidelines

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

1

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
2

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
3

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

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 proper torque specifications important for engine bolts?

Correct torque is crucial to ensure even clamping force across mating surfaces. Over-tightening can stretch or break bolts and distort components, while under-tightening can lead to leaks, vibrations, and component failure. Specifically, in the 2.2L engine, improper torque on the cylinder head bolts can lead to head gasket failure and coolant leaks, while insufficient torque on the flywheel can cause it to loosen, potentially damaging the transmission.

Q2

What tools are essential for torquing engine bolts?

A high-quality torque wrench is essential. It is advisable to use a click-type torque wrench or a digital torque wrench for precise readings. Always use the correct size and type of socket for the bolts you are working with to prevent slippage and damage. A breaker bar can help initially loosen stubborn bolts, while a set of universal joints and extensions can access hard-to-reach areas. When installing the flywheel, a clutch alignment tool is necessary to center the clutch disc before tightening the bolts.

Q3

Do I need to replace bolts after removing them?

It depends on the bolt. Certain bolts, like cylinder head bolts on the 2.2L engine, are torque-to-yield (TTY) or stretch bolts and must always be replaced after removal because they have been permanently deformed. Other bolts, such as intake manifold bolts, can be reused if they are in good condition; however, it is often advisable to replace them to ensure consistent clamping force, especially after years of exposure to engine heat and vibration. Always refer to the service manual for your specific engine.

Q4

What if I don't have the exact torque specification?

Using a generic torque specification is highly discouraged and can cause significant damage. Torque specifications are very specific to each component of the 2.2L engine and are designed based on material properties and assembly needs. If you don't have the exact torque values, consult the original service manual for the specific year and model of your Audi S4 2.2L engine or use a reputable online database. Guessing, or using general guidelines from other sources, can easily lead to stripped threads, leaks, or premature failure. If you're unsure, seek advice from a professional mechanic who specializes in Audi vehicles.

Q5

How does temperature affect torque specifications?

Torque specifications are generally given for room temperature. However, engine components expand when heated. In most cases, for components not directly heated by combustion, this difference is negligible for torquing bolts. However, when tightening an exhaust manifold, it's preferable to do so when the system is cool to avoid over-tightening from expansion. In general, always refer to the service manual for specific guidelines.

Environmental Considerations

Temperature, humidity, and seasonal effects on torque specifications

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

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

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 tool for applying precise torque to fasteners.

  • 1/2" drive
  • Range of 5-150 ft-lbs (or equivalent Nm)
  • Audible click or digital readout
Learn more

Torque Angle Gauge

Used to measure and apply precise rotational angles after initial torque settings.

  • 360 degree scale
  • Adjustable arm
  • Clear markings
Learn more

Socket Set (Metric)

A comprehensive set of metric sockets to fit various bolt and nut sizes on the 2.2l engine.

  • Sizes ranging from 8mm to 24mm
  • 6-point design
  • Various drive sizes (1/4", 3/8", 1/2")
Learn more

Extension Bars

Used to extend reach for fasteners in recessed or hard to reach locations.

  • Various lengths
  • Different drive sizes available
  • Durable construction
Learn more

Universal Joint (Swivel)

Allows sockets to be used at an angle, useful for tight spaces.

  • Various drive sizes
  • Full range of motion
  • Durable construction
Learn more
Service Procedures

Cylinder Head Bolt Torque Procedure

Procedure for properly torquing the cylinder head bolts on the 2.2l engine. This is a multi-step process requiring specific torque values and angles.

  • Clean threads of bolts and cylinder block.
  • Apply new bolts or confirm old bolts are within spec for reuse.
  • Install cylinder head, ensuring proper alignment.
  • Tighten all cylinder head bolts in the specified sequence to 40 Nm.
  • Re-torque all bolts in the specified sequence to 60 Nm.
  • Using a torque angle gauge, tighten all bolts in the specified sequence 90 degrees.
  • Again, tighten all bolts in the specified sequence 90 degrees.
  • Verify torque after final angle adjustment
View full procedure

Intake Manifold Bolt Torque Procedure

Procedure for correctly torquing the intake manifold bolts.

  • Install intake manifold to head.
  • Tighten all intake manifold bolts in the specified sequence to 25 Nm.
View full procedure

Exhaust Manifold Bolt Torque Procedure

Procedure for correctly torquing the exhaust manifold bolts.

  • Install exhaust manifold to head.
  • Tighten all exhaust manifold bolts in the specified sequence to 25 Nm.
View full procedure

Camshaft Bearing Cap Torque Procedure

Procedure for properly torquing the camshaft bearing cap bolts.

  • Install camshaft bearing caps, ensuring proper alignment.
  • Tighten all bolts in the specified sequence to 20 Nm.
View full procedure
Technical Service Bulletins

Cylinder Head Bolt Re-Torque Recommendations

1995-01-15

This bulletin outlines specific concerns and revised torquing procedures for cylinder head bolts on the 2.2L turbo engine due to reported head gasket failures.

1991-1994 Audi S4

Resolution: Always use new cylinder head bolts. Tighten to 40 Nm, then 60 Nm, then 90 degrees, then a final 90 degrees.

Intake Manifold Gasket Installation

1993-06-22

This bulletin explains proper installation and sealing techniques for the intake manifold gasket on 2.2L turbo engines to prevent vacuum leaks.

1991-1994 Audi S4

Resolution: Clean all mating surfaces. Ensure new gasket is correctly aligned. Tighten manifold bolts to 25 Nm.

About the Author

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Alan Montanye - Automotive Technical Specialist
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Alan Montanye

Automotive Technical Specialist

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