Buick Envision 2016-2020 Fuel System Bolt Torque Specifications & Line Fittings
Buick Envision 2016-2020

Buick Envision 2016-2020 Fuel System Bolt Torque Specifications

This page provides detailed torque specifications for fuel system bolts on the 2016-2020 Buick Envision, including fuel line, fuel pump, and fuel rail 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

Fuel Rail And Injectors

This section covers the torque specifications for components related to the fuel rail and fuel injectors, crucial for delivering fuel to the engine's cylinders.

1

Fuel Rail Mounting Bolts

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
These bolts secure the fuel rail to the intake manifold or cylinder head. Ensure proper torque to prevent fuel leaks and maintain correct fuel pressure.
2

Fuel Injector Mounting Bolts

M6 x 1.0
Torque Value
7 ft-lbs (10 N·m)
Important Notes
These bolts secure the fuel injectors to the fuel rail and intake manifold. Proper torque is crucial to prevent fuel leaks around injector seals and ensure correct seating.

Fuel Pump And Filter

This section outlines the torque specifications for the fuel pump and fuel filter mounting components.

1

Fuel Pump Mounting Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
These bolts secure the fuel pump assembly to the fuel tank. Ensure proper torque to prevent leaks and maintain pump function.
2

Fuel Filter Mounting Bolt/Nut

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
This refers to the bolt or nut that secures the fuel filter housing or bracket. Correct torque prevents leaks at the filter connections and maintains proper filter function.

Fuel Tank And Filler

This section covers the torque specifications for components related to the fuel tank and filler neck.

1

Fuel Tank Strap Bolts

M10 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
These bolts secure the fuel tank straps to the vehicle frame. Proper torque ensures the fuel tank is securely attached.
2

Fuel Filler Neck Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
These bolts secure the fuel filler neck to the vehicle body. Correct torque ensures a proper seal to prevent fuel leaks.

High Pressure Fuel Pump

This section provides the torque specifications for the high-pressure fuel pump, typically found in direct injection systems.

1

High-Pressure Fuel Pump Mounting Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
These bolts secure the high-pressure fuel pump to the engine. Proper torque is crucial for correct mounting and leak-free operation. This value is an estimate based on typical bolt sizes and applications.

Fuel Line Fittings

This section specifies the torque for fuel line fittings and connectors, including flare fittings and banjo bolts.

1

Fuel Line Fitting/Connector Nut

M12 x 1.5
Torque Value
14 ft-lbs (19 N·m)
Important Notes
This torque specification applies to typical fuel line flare fittings or banjo bolts. Use new sealing washers when applicable. This value is an estimate based on typical fitting sizes and applications.

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 is it crucial to use the correct torque specification for fuel system bolts?

Using the correct torque ensures a proper seal, preventing fuel leaks which pose a fire hazard. Under-torquing can lead to leaks, while over-torquing can damage the bolt, threads, or the component itself, also leading to leaks and potential failure. For example, over-torquing a fuel injector retaining bolt might crack the injector housing.

Q2

Where can I find the exact torque specifications for my 2016-2020 Buick Envision's fuel system bolts?

The most reliable source for torque specifications is the official Buick service manual for your specific model year. These manuals provide precise torque values for every fastener in the fuel system. You can also find this information on some subscription-based online repair databases.

Q3

Can I reuse fuel system bolts?

Generally, it's best practice to replace fuel system bolts, especially those that are torque-to-yield (TTY). These bolts are designed to stretch upon tightening, which provides proper clamping force. Reusing them can lead to improper clamping force and leaks. If you do reuse a bolt, carefully inspect it for damage, stretch, or deformation.

Q4

What should I do if I accidentally over-torque a fuel system bolt?

If you suspect you have over-torqued a bolt, it is best to replace it with a new bolt and the corresponding fuel system component. An over-torqued bolt can be stretched and therefore weakened. Do not reuse it. You should also carefully check the mating component for damage or cracks. You might need to replace more than just the bolt.

Q5

What tools do I need to properly torque fuel system bolts?

You will need a calibrated torque wrench. A standard wrench will not provide the accurate torque you require. The torque wrench should be compatible with the size of the bolt you are tightening, and it is recommended you use a socket instead of an open-ended wrench for accurate and secure tightening. A torque angle meter might be needed for some bolts depending on whether they are torqued to angle. Refer to your service manual.

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 (1/4" Drive)

A calibrated torque wrench with a 1/4" drive, capable of accurately measuring torque in inch-pounds (in-lbs) and/or Newton-meters (Nm).

  • Accurate torque application
  • Precise measurements
  • Easy to read scale
Learn more

Torque Wrench (3/8" Drive)

A calibrated torque wrench with a 3/8" drive, capable of accurately measuring torque in foot-pounds (ft-lbs) and/or Newton-meters (Nm).

  • Accurate torque application
  • Precise measurements
  • Easy to read scale
Learn more

Socket Set (Metric)

A comprehensive socket set in metric sizes, necessary for accessing various fuel system bolts.

  • Various metric socket sizes
  • Durable construction
Learn more

Extension Bars

Extension bars in various lengths, used to reach difficult to access bolts.

  • Multiple sizes
  • Sturdy materials
Learn more
Service Procedures

Fuel Rail Bolt Torque Procedure

Procedure for correctly tightening the fuel rail bolts on 2016-2020 Buick Envision models.

  • Locate the fuel rail bolts.
  • Refer to the vehicle's service manual for the specific torque specification (typically in-lbs or Nm).
  • Using the appropriate socket and torque wrench, tighten the bolts to the specified torque, in a cross pattern.
  • Double-check the torque on each bolt to ensure accuracy.
  • Verify no fuel leaks after torquing the bolts.
View full procedure

Fuel Line Connection Torque Procedure

Procedure for correctly tightening the fuel line connections on 2016-2020 Buick Envision models.

  • Locate the fuel line connection points.
  • Refer to the vehicle's service manual for the specific torque specification (typically ft-lbs or Nm).
  • Using the appropriate wrench and torque wrench, tighten the connections to the specified torque.
  • Double-check the torque on each fitting to ensure accuracy.
  • Verify no fuel leaks after torquing the fuel line connections.
View full procedure

Fuel Injector Mounting Bolt Torque Procedure

Procedure for correctly tightening the fuel injector mounting bolts on 2016-2020 Buick Envision models.

  • Locate the fuel injector mounting bolts.
  • Refer to the vehicle's service manual for the specific torque specification (typically in-lbs or Nm).
  • Using the appropriate socket and torque wrench, tighten the bolts to the specified torque in a cross pattern.
  • Double-check the torque on each bolt to ensure accuracy.
  • Verify no fuel leaks after torquing the fuel injector mounting bolts.
View full procedure
Technical Service Bulletins

Fuel Leak at Fuel Rail

2017-03-15

Some 2016-2017 Buick Envision models may experience fuel leaks at the fuel rail due to improper torque specifications.

2016-2017

Resolution: Verify fuel rail bolt torque to the specification in the service manual. Replace any damaged components.

Fuel Line Connector O-Ring Failure

2018-10-22

A small number of 2017-2019 Buick Envision models have reported fuel leaks at the quick connect fuel line connectors. Inspection reveals damaged O-rings at the connectors.

2017-2019

Resolution: Inspect O-rings for damage. Replace O-rings and ensure proper torque on fuel line fittings.

Fuel Injector Mounting Bolt Back Out

2019-12-01

Some reports of fuel injector mounting bolts backing out have been documented on 2018-2020 Buick Envision vehicles. Inspection reveals incorrect torque values have been applied.

2018-2020

Resolution: Verify fuel injector mounting bolt torque to the specification in the service manual. Apply thread locker as a preventative measure.

About the Author

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Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

Automotive Technical Specialist

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