Acura NSX 1990-2005 3.0L Engine Bolt Torque Specifications & Fastener Values
Acura NSX 1990-2005

Acura NSX 1990-2005 3.0L Engine Bolt Torque Specifications

Comprehensive torque specifications for all critical bolts on the 3.0L engine of the 1990-2005 Acura NSX, including cylinder head, main bearing caps, connecting rods, and other vital 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

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Torque Calculator

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3.0l-engine Cylinder Head

Torque specifications for the cylinder head and related components.

1

Cylinder Head Bolts

M12 x 1.75
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Follow specific tightening sequence as detailed in the service manual. Ensure threads are clean and lightly lubricated.
2

Camshaft Cap Bolts

M8 x 1.25
Torque Value
10 ft-lbs (14 N·m)
Important Notes
Tighten camshaft cap bolts in the correct sequence. Ensure the camshaft journals are properly lubricated.
3

Valve Cover Bolts

M6 x 1.0
Torque Value
9 ft-lbs (12 N·m)
Important Notes
Do not overtighten. Use a new valve cover gasket.
4

Spark Plugs

M14 x 1.25
Torque Value
13 ft-lbs (18 N·m)
Important Notes
Ensure threads are clean and lightly lubricated with anti-seize compound. Do not overtighten.
5

Rocker Arms/Shafts Bolts

M8 x 1.25
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Tighten evenly to avoid binding. Ensure rocker arms and shafts are properly lubricated.
6

Exhaust Manifold/Headers to Cylinder Head Bolts

M10 x 1.5
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Use a new exhaust manifold gasket. Tighten in the correct sequence. Ensure the manifold is properly aligned.

3.0l-engine Block

Torque specifications for engine block components.

1

Main Bearing Bolts

M12 x 1.75
Torque Value
56 ft-lbs (76 N·m)
Important Notes
Apply engine oil to bolt threads and under bolt heads. Tighten in the specified sequence.
2

Oil Pan Bolts

M6 x 1.0
Torque Value
7 ft-lbs (9 N·m)
Important Notes
Convert inch-lbs to ft-lbs (80 inch-lbs = 6.66 ft-lbs, rounded to 7 ft-lbs). Use a new oil pan gasket and tighten in a criss-cross pattern to ensure even sealing.
3

Oil Drain Plug Bolt

M14 x 1.5
Torque Value
29 ft-lbs (39 N·m)
Important Notes
Use a new crush washer or sealing ring. Do not overtighten.
4

Knock Sensor Bolt

M8 x 1.25
Torque Value
15 ft-lbs (20 N·m)
Important Notes
Do not over tighten, ensure the sensor is clean and properly installed.
5

Water Pump Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Use a new water pump gasket and tighten evenly.
6

Coolant Temperature Sensor Bolt/Fitting

M10 x 1.0 (estimated)
Torque Value
12 ft-lbs (16 N·m)
Important Notes
May be a tapered fitting instead of a bolt. Do not overtighten. Estimated value.

3.0l-engine Rotating Assembly

Torque specifications for components related to the rotating assembly.

1

Connecting Rod Nuts

M9 x 1.0
Torque Value
18 ft-lbs (24 N·m)
Important Notes
Apply engine oil to threads and under the nuts. Ensure proper bearing clearance is achieved. Use new nuts if necessary.
2

Flywheel Bolts

M10 x 1.25
Torque Value
76 ft-lbs (103 N·m)
Important Notes
Apply thread locking compound to the bolt threads. Tighten in a star pattern.
3

Crankshaft Pulley/Harmonic Balancer Bolt

M16 x 1.5
Torque Value
130 ft-lbs (176 N·m)
Important Notes
Apply engine oil to the bolt threads and under the bolt head. Use a crankshaft holding tool to prevent rotation when torquing.

3.0l-engine Timing System

Torque specifications for components related to the timing system.

1

Timing Belt/Chain Tensioner Bolt

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Ensure correct tensioner operation before tightening. Improper torque can affect timing.
2

Camshaft Sprocket Bolt

M10 x 1.25
Torque Value
26 ft-lbs (35 N·m)
Important Notes
Hold the camshaft from rotating using a suitable tool. Ensure the sprocket is aligned.

3.0l-engine Intake System

Torque specifications for components related to the intake system.

1

Throttle Body Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Use a new throttle body gasket.
2

Intake Manifold Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Use a new intake manifold gasket. Tighten in the correct sequence.
3

EGR Valve Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Use a new gasket if required. Ensure valve is properly aligned.
4

Fuel Rail Bolts

M6 x 1.0
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Do not overtighten. Ensure proper fuel rail alignment.
5

Fuel Injector Bolts

M6 x 1.0
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Do not overtighten. Use new injector seals if required.
6

Intake Air Temperature (IAT) Sensor Bolt/Fitting

M6 x 1.0 (estimated)
Torque Value
8 ft-lbs (11 N·m)
Important Notes
May be a tapered fitting instead of a bolt. Do not overtighten. Estimated value.

3.0l-engine Cooling System

Torque specifications for components related to the cooling system.

1

Water Pump Pulley Bolts

M8 x 1.25
Torque Value
16 ft-lbs (22 N·m)
Important Notes
Ensure pulley is correctly aligned.
2

Thermostat Housing Bolts

M6 x 1.0
Torque Value
9 ft-lbs (12 N·m)
Important Notes
Use a new thermostat housing gasket. Do not overtighten.

3.0l-engine Accessory Drive

Torque specifications for components related to the accessory drive system.

1

Serpentine/Accessory Drive Belt Tensioner Bolt

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Ensure correct belt tension before final tightening. Do not overtighten.
2

Drive Belt Idler Pulley Bolt

M10 x 1.5
Torque Value
33 ft-lbs (45 N·m)
Important Notes
Ensure the idler pulley is properly aligned and rotates freely.

3.0l-engine Ignition System

Torque specifications for components related to the ignition system.

1

Ignition Coil Bolt

M6 x 1.0
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Do not overtighten, ensure proper alignment and clean mounting surfaces.
2

Crankshaft Position Sensor (CKP) Bolt

M6 x 1.0
Torque Value
8 ft-lbs (11 N·m)
Important Notes
Ensure sensor is correctly positioned and clean.

3.0l-engine Lubrication System

Torque specifications for components related to the lubrication system.

1

Oil Filter Housing Bolt

N/A
Torque Value
0 ft-lbs (0 N·m)
Important Notes
Hand tighten only, avoid overtightening, Use new o-ring.

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 precise torque specifications important when working on the 3.0L NSX engine?

Accurate torque application ensures proper clamping force, preventing leaks, component damage, and potential engine failure. Over-torquing can strip threads or deform parts, while under-torquing can lead to loosening and leaks. For instance, improperly torqued cylinder head bolts can cause head gasket failure and coolant leaks, resulting in severe engine damage. Always use a calibrated torque wrench and follow the manufacturer's torque sequence.

Q2

Should I replace bolts when working on the 3.0L NSX engine?

It's generally good practice to replace critical fasteners like head bolts, main bearing cap bolts, and connecting rod bolts, especially if they are torque-to-yield (TTY) bolts. These bolts are designed to stretch upon tightening and should not be reused. Reusing TTY bolts can result in improper clamping force and potential component failure. While other bolts *may* be reusable, inspect for wear, stretching, or damage. When in doubt, replace them.

Q3

How often should I check the torque of engine components after reassembly?

After initial reassembly, a 're-torque' after the engine has run for a short period, typically after the first heat cycle (engine reaching operating temperature and then cooling) is a good practice for some components. This accounts for gasket settling and bolt stretch. Then, follow the maintenance schedule; for standard components, unless there are indications of a problem (leaks or unusual noises), standard maintenance is sufficient. For components with frequent changes or high performance mods, a more frequent check and maintenance is prudent. Consult the NSX service manual for specific instructions.

Q4

Can I use aftermarket bolts on my 3.0L NSX engine?

Yes, aftermarket bolts can be used. However, verify that they meet or exceed OEM specifications in terms of material strength and dimensions. Using improperly rated aftermarket bolts can cause significant damage. Always verify the aftermarket bolt's torque specification matches or is similar to the OEM specification. High performance applications may require increased torque specifications.

Q5

What happens if I don't follow the tightening sequence on the 3.0L engine?

Following the proper tightening sequence is critical for uniform clamping force and to prevent warping or stress. Failing to follow the sequence, particularly for cylinder heads or manifolds, can lead to leaks and component failure. Improper torque sequencing can cause the parts to warp and not seal properly leading to leaks and possible engine damage. For example, if you tighten one side of the cylinder head down fully before the other, this can cause the head to warp, requiring costly machining and engine disassembly.

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 (1/2 inch drive)

A calibrated torque wrench is essential for accurately tightening bolts to specification. 1/2 inch drive is recommended for the range of torque values on the NSX engine.

  • Click-type mechanism
  • Wide torque range (e.g., 20-150 ft-lbs)
  • Calibration certificate
Learn more

Torque Wrench (3/8 inch drive)

A smaller torque wrench is useful for smaller bolts that don't require as much torque.

  • Click-type mechanism
  • Lower torque range (e.g., 5-80 ft-lbs)
  • Calibration certificate
Learn more

Socket Set (Metric)

A comprehensive set of metric sockets in various sizes to fit all the bolts on the 3.0L engine.

  • Various socket sizes (e.g., 8mm - 24mm)
  • 6-point sockets for better grip
  • 1/2 and 3/8 inch drive options
Learn more

Socket Extensions

Socket extensions of various lengths to reach recessed bolts on the engine.

  • 3 inch, 6 inch and 12 inch lengths
  • 1/2 and 3/8 inch drive options
  • Durable construction
Learn more

Torque Angle Meter

An angle meter may be needed for certain bolts that require a torque-plus-angle method of tightening.

  • Easy to read scale
  • Magnetic attachment
  • Adjustable arm
Learn more
Service Procedures

Cylinder Head Bolt Tightening

Procedure for correctly torquing the cylinder head bolts on the 3.0L NSX engine. Requires multiple steps and a specific sequence.

  • Clean threads on bolts and in the block.
  • Apply a thin coat of clean engine oil to bolt threads and under the bolt heads.
  • Hand tighten all bolts in proper sequence (see service manual).
  • Torque all bolts to first specified torque value (e.g., 22 ft-lbs) in proper sequence.
  • Torque all bolts to the second specified torque value (e.g., 47 ft-lbs) in proper sequence.
  • Torque all bolts to the specified angle, if required, in proper sequence.
  • Verify torque values on all bolts.
View full procedure

Connecting Rod Bolt Tightening

Procedure for correctly torquing the connecting rod bolts. These are typically torque-to-yield and require specific attention.

  • Clean threads on bolts and rods.
  • Apply a thin coat of clean engine oil to bolt threads and under the bolt heads.
  • Hand tighten all bolts.
  • Torque all bolts to first specified torque value (e.g., 14 ft-lbs).
  • Torque all bolts to the second specified angle (e.g., 90 degrees), if required. Refer to NSX service manual for correct angle.
  • Verify torque values and angles of all bolts.
View full procedure

Main Bearing Cap Bolt Tightening

Procedure for correctly torquing the main bearing cap bolts, also requires a specific sequence.

  • Clean threads on bolts and in the block.
  • Apply a thin coat of clean engine oil to bolt threads and under the bolt heads.
  • Hand tighten all bolts.
  • Torque all bolts to first specified torque value in proper sequence.
  • Torque all bolts to the second specified torque value in proper sequence.
  • Verify torque values on all bolts.
View full procedure

Intake Manifold Bolt Tightening

Procedure for tightening the bolts on the intake manifold. Typically involves a lower torque range.

  • Hand tighten all bolts.
  • Torque all bolts to the specified value in proper sequence.
  • Verify torque values on all bolts.
View full procedure
Technical Service Bulletins

Cylinder Head Bolt Re-Torque Recommendation

1997-05-12

A slight variation in cylinder head gasket crush during the initial running in period may require a re-torque of the head bolts.

1991-1996

Resolution: Re-torque cylinder head bolts to final specification after 500-1000 miles of driving. Follow original tightening sequence.

Connecting Rod Bolt Material Update

2000-11-20

A change in connecting rod bolt material required a minor adjustment to the final torque angle

2000-2005

Resolution: Refer to the updated NSX service manual for correct torque and angle specifications for connecting rod bolts, as the torque specifications have changed.

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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