GMC Envoy 2002-2009 4.2L Engine Bolt Torque Specifications & Fastener Values
GMC Envoy 2002-2009

GMC Envoy 2002-2009 4.2L Engine Bolt Torque Specifications

Detailed torque specifications for the 4.2L engine bolts in the 2002-2009 GMC Envoy, including cylinder head, main bearing, and connecting rod bolts.

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

Components related to the cylinder head, including bolts for sealing, valve operation, and timing.

1

Cylinder Head Bolts

M10 x 1.5
Important Notes
Follow the manufacturer's torque sequence for proper sealing. Estimated bolt size based on typical cylinder head bolts.
2

Rocker Arms/Shafts Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Ensure proper valve operation by tightening evenly. Estimated bolt size based on typical rocker arm bolts.

Crankshaft And Bearings

Components related to the crankshaft, main bearings, and connecting rods.

1

Main Bearing Bolts

M12 x 1.75
Torque Value
63 ft-lbs (85 N·m)
Important Notes
Ensure proper alignment of the crankshaft. Estimated bolt size based on typical main bearing bolts.
2

Connecting Rod Nuts

M9 x 1.0
Torque Value
24 ft-lbs (33 N·m)
Important Notes
Ensure proper piston movement. Estimated bolt size based on typical connecting rod bolts.

Timing System

Components related to the timing belt/chain, sprockets, and tensioners.

1

Camshaft Sprocket Bolt

M12 x 1.5
Torque Value
80 ft-lbs (108 N·m)
Important Notes
Ensure proper timing alignment. Estimated bolt size based on typical camshaft sprocket bolts.
2

Timing Belt/Chain Tensioner Bolt

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Ensure proper tension on the timing belt/chain. Estimated bolt size based on typical tensioner bolts.

Intake And Exhaust

Components related to the intake manifold, exhaust manifold, and fuel system.

1

Intake Manifold Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Ensure a proper seal to prevent vacuum leaks. Estimated bolt size based on typical intake manifold bolts.
2

Exhaust Manifold Bolts

M8 x 1.25
Torque Value
26 ft-lbs (35 N·m)
Important Notes
Ensure a proper seal to prevent exhaust leaks. Estimated bolt size based on typical exhaust manifold bolts.

Cooling System

Components related to the water pump, thermostat housing, and coolant flow.

1

Water Pump Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Ensure proper coolant circulation. Estimated bolt size based on typical water pump bolts.
2

Thermostat Housing Bolts

M6 x 1.0
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Ensure proper coolant flow. Estimated bolt size based on typical thermostat housing bolts.

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

What are the torque specifications for the cylinder head bolts on a 4.2L engine?

The cylinder head bolts on a 2002-2009 GMC Envoy with a 4.2L engine should be torqued in three stages: first to 22 lb-ft, then to 44 lb-ft, and finally an additional 90-degree turn. Always follow the manufacturer's sequence to avoid warping the cylinder head.

Q2

How often should I check the torque on engine components?

Torque checks are recommended during routine maintenance or after any major engine work. For example, after replacing the intake manifold gasket, recheck the torque on the intake manifold bolts after 500 miles to ensure they haven't loosened due to thermal cycling.

Q3

Can I reuse head bolts on a 4.2L engine?

No, the cylinder head bolts on the 4.2L engine are torque-to-yield (TTY) bolts and should not be reused. Reusing them can lead to improper clamping force and potential engine damage. Always replace them with new bolts during reassembly.

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 precision tool used to apply a specific torque to a fastener such as a bolt or nut.

  • Adjustable torque settings
  • Calibrated for accuracy
Learn more

Socket Set

A set of sockets in various sizes to fit different bolt heads.

  • Includes both metric and standard sizes
  • Durable construction
Learn more

Thread Locker

A chemical compound used to secure bolts and prevent them from loosening due to vibration.

  • High-strength formula
  • Temperature resistant
Learn more
Service Procedures

Cylinder Head Bolt Torque Procedure

Detailed steps for properly torquing the cylinder head bolts on a 4.2L engine.

  • Clean the bolt threads and bolt holes thoroughly.
  • Apply a small amount of engine oil to the threads and under the bolt heads.
  • Tighten the bolts in the specified sequence to 30 Nm (22 lb-ft).
  • Turn each bolt an additional 90 degrees in the specified sequence.
  • Turn each bolt an additional 90 degrees again in the specified sequence.
View full procedure

Main Bearing Cap Bolt Torque Procedure

Steps for torquing the main bearing cap bolts on a 4.2L engine.

  • Clean the bolt threads and bolt holes thoroughly.
  • Apply a small amount of engine oil to the threads and under the bolt heads.
  • Tighten the bolts in the specified sequence to 50 Nm (37 lb-ft).
  • Turn each bolt an additional 60 degrees in the specified sequence.
View full procedure
Technical Service Bulletins

Engine Bolt Torque Specification Update

2005-03-15

Updated torque specifications for engine bolts on 2002-2005 GMC Envoy models with the 4.2L engine.

2002-2005 GMC Envoy

Resolution: Follow the updated torque specifications provided in the bulletin to ensure proper engine assembly and performance.

Cylinder Head Bolt Loosening Issue

2007-08-22

Reports of cylinder head bolts loosening over time on 2002-2007 GMC Envoy models with the 4.2L engine.

2002-2007 GMC Envoy

Resolution: Apply thread locker to the cylinder head bolts and follow the revised torque procedure to prevent loosening.

About the Author

Expert automotive knowledge and experience

Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

Automotive Technical Specialist

ASE Master Certified Technician with over a decade of hands-on experience in automotive repair and diagnostics.

Facebook Contact
15+ Years
Experience
500+ Guides
Guides
50+ Makes
Vehicles
1000+ Solutions
Solutions

Diagnostic

Specialized in advanced diagnostic techniques using modern scan tools and oscilloscopes.

Repair

Expert in both traditional mechanical repairs and modern vehicle systems.

Additional Expertise

Documentation

Created over 500 detailed repair guides and technical documents.

Training

Conducted technical training sessions and contributed to repair databases.

Certifications & Research

Certifications

  • ASE Master Technician Certification
  • Advanced Diagnostic Specialist
  • Hybrid/Electric Vehicle Systems
  • Performance Tuning Expert

Research & Community

Actively researches emerging technologies and contributes to automotive forums.

Legal Disclaimer

Important information about using this content

Always refer to your vehicle's service manual and take appropriate safety precautions when performing any maintenance or repairs.

General Information
The information provided on this website is for general informational purposes only. While we strive to maintain accuracy in our content, all specifications, procedures, and technical information should be verified against your vehicle's official service manual or with the manufacturer directly.
Warranty & Liability

The content on this website is provided "as is" without any representations or warranties, express or implied. We make no representations or warranties regarding the accuracy, completeness, or availability of the information.

We shall not be liable for any direct, indirect, special, or consequential damages arising from the use of information on this website.

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.
Intellectual Property
All content, including text, images, and specifications, is protected by copyright and other intellectual property laws. Any unauthorized use or reproduction is prohibited.

© 2025 GMC Specs. All rights reserved.

Privacy Policy Terms of Service