Buick LaCrosse 2017-2019 Fuel System Bolt Torque Specifications & Line Fittings
Buick LaCrosse 2017-2019

Buick LaCrosse 2017-2019 Fuel System Bolt Torque Specifications

This page provides detailed torque specifications for fuel system bolts on the 2017-2019 Buick LaCrosse. Includes specifications for fuel rail, fuel line, and fuel pump mounting 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

This subsystem includes the fuel rail, injectors, and associated mounting hardware responsible for delivering fuel to the engine's cylinders. Proper torque is essential for leak-free operation and correct fuel pressure delivery.

1

Fuel Rail Mounting Bolts

M6 x 1.0
Torque Value
7.4 ft-lbs (10 N·m)
Important Notes
Ensure the fuel rail is properly seated before tightening. Tighten all bolts in a crisscross pattern to evenly distribute pressure.
2

Fuel Injector Mounting Bolts/Screws

M5 x 0.8
Torque Value
7.4 ft-lbs (10 N·m)
Important Notes
Ensure injector seals are correctly installed. These fasteners are typically small and require delicate handling. Tighten gently.
3

Fuel Pressure Sensor Mounting Bolt/Nut

M6 x 1.0
Torque Value
7.4 ft-lbs (10 N·m)
Important Notes
Tighten to specified torque to prevent leaks and maintain correct sensor readings. The sensor's o-ring or sealing washer must be properly seated.

Fuel Pump And Tank

This subsystem includes the fuel pump, sending unit, filler neck, and associated hardware that are part of the fuel storage and delivery to the engine. Proper sealing and securing of these components are critical for safety and functionality.

1

Fuel Pump Module Mounting Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Ensure the fuel pump module is correctly aligned in the fuel tank. Tighten all bolts evenly to maintain a proper seal.
2

Fuel Filler Neck Mounting Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Ensure the fuel filler neck seal is correctly positioned. Tighten evenly to prevent fuel leaks and fume release.
3

Fuel Tank Sending Unit Retaining Ring

N/A
Torque Value
44.5 ft-lbs (60 N·m)
Important Notes
This value is an average estimate, torque may vary based on design. Ensure the retaining ring is fully and correctly engaged, this often requires a specialized tool for installation.

Fuel Lines And Filter

This subsystem covers the fuel lines, filter, and related hardware responsible for proper fuel delivery through the system. Correct tightening of fittings is crucial to prevent leaks.

1

Fuel Filter Mounting Bolt/Nut

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Ensure proper bracket alignment before tightening. Correct torque prevents movement of the fuel filter.
2

Fuel Line Fittings (Banjo Bolts/Compression Fittings)

Varies Based on Design, M12 x 1.5 estimated
Torque Value
20 ft-lbs (27 N·m)
Important Notes
Torque value is an estimate and varies by fitting type and size. Refer to specific instructions for your vehicle's fittings. Avoid over-tightening as this can damage the fitting or seal. May require turn of the nut after initial torque value. Often will use a 'backing' wrench to prevent twisting the line and fitting during installation.

Fuel Pump High Pressure

If Equipped, this subsystem handles the direct injection high pressure fuel pump. Proper mounting ensures proper operation and no leaks.

1

High Pressure Fuel Pump Mounting Bolts

M8 x 1.25
Torque Value
18 ft-lbs (25 N·m)
Important Notes
Ensure the pump is correctly positioned before tightening. Tighten evenly to maintain a proper seal.

Access Panel

This subsystem includes the access panel to the fuel tank, usually located under the rear seats or in the trunk. Proper sealing is critical to preventing fumes from entering the passenger cabin.

1

Fuel Tank Access Panel Bolts/Screws

M5 x 0.8
Torque Value
7.4 ft-lbs (10 N·m)
Important Notes
Tighten evenly, do not overtighten. Ensure the seal is correctly aligned. Under-tightening can also cause fumes to permeate the passenger compartment.

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 using the correct torque specification important for fuel system bolts?

Using the correct torque specification for fuel system bolts is crucial for several reasons. Over-tightening can damage the bolt, threads, or sealing surfaces, leading to leaks. Under-tightening can also cause leaks due to insufficient clamping force. Correct torque ensures a secure, leak-free seal, preventing fuel leaks and potential fire hazards. For example, an improperly torqued fuel injector rail bolt might leak, creating a volatile situation.

Q2

What happens if I overtighten a fuel system bolt?

Overtightening a fuel system bolt can lead to several issues. The bolt threads can strip, the bolt itself can break, or the mating surface can become deformed. This damage often results in a leak, which in the fuel system can be extremely dangerous. Additionally, overtightening can crush gaskets or o-rings, preventing a proper seal and resulting in fuel leaks. For example, an overtightened fuel pump mounting bolt can crack the plastic housing, causing a leak.

Q3

Can I reuse fuel system bolts?

It is generally not recommended to reuse fuel system bolts, especially those designed for one-time use (often called torque-to-yield bolts). These bolts are designed to stretch upon tightening and may not provide the same clamping force when reused, potentially leading to leaks. While some bolts may be reusable, always consult the manufacturer's service manual for specific recommendations. If there is any doubt, it's best to use new bolts to ensure a proper seal.

Q4

What type of torque wrench should I use?

A calibrated torque wrench, preferably a click-type or digital torque wrench, is essential for tightening fuel system bolts. A beam-type torque wrench can also be used, but it is not as precise. The torque wrench should have a range that encompasses the specified torque for the bolts you are working on. Always check the calibration of your torque wrench periodically to ensure accuracy. For example, using an inaccurate wrench could result in tightening to 18 lb-ft when only 13 lb-ft is specified.

Q5

How do I determine the correct torque for a fuel system bolt if I don't have the specific manual?

While specific torque specs are usually model and component-specific, general rules of thumb and bolt size can sometimes give you a general estimate; However, this is STRONGLY DISCOURAGED. Always seek a repair manual or credible database with the proper specifications for your vehicle. Incorrect torque settings will almost certainly lead to failure. If you are unsure, it is best to consult with a qualified mechanic or auto service professional.

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" or 3/8" Drive)

A calibrated torque wrench is essential for accurately tightening fuel system bolts to specified torque values. Using the incorrect torque can lead to leaks or component damage.

  • Accurate torque readings
  • Click-type or digital display
  • Appropriate range for fuel system bolts (e.g., 5-25 ft-lbs or 7-35 Nm)
Learn more

Socket Set (Metric)

A set of metric sockets is needed to fit the various sizes of bolts and fasteners used in the Buick Lacrosse fuel system. Common sizes include 8mm, 10mm, 12mm, and 13mm.

  • Various sizes (typically 8-19mm)
  • 6-point sockets recommended
  • Durable construction
Learn more

Extension Bars

Extension bars help access hard-to-reach fuel system fasteners.

  • Various lengths available
  • Secure connection to sockets and wrench
Learn more
Service Procedures

Fuel Rail Bolt Tightening Procedure

This procedure outlines the steps for tightening the fuel rail bolts to the correct torque specification.

  • Locate the fuel rail and the bolts securing it to the engine.
  • Using the correct metric socket, lightly thread all the fuel rail bolts by hand to ensure they are properly aligned.
  • Use the calibrated torque wrench to tighten each bolt to the correct torque specification (typically 15-20 ft-lbs or 20-27 Nm). Follow a star or alternating pattern when tightening the bolts.
  • Re-check all bolts to ensure they are at the proper torque setting.
View full procedure

Fuel Line Connection Bolt Tightening Procedure

This procedure outlines the steps for properly tightening fuel line connection bolts to prevent leaks.

  • Ensure the fuel line is properly seated in its connection.
  • Using the correct metric socket, lightly thread the fuel line connection bolt by hand to ensure proper alignment.
  • Use the calibrated torque wrench to tighten the connection bolt to the correct torque specification (typically 10-15 ft-lbs or 14-20 Nm). Do not overtighten.
  • Inspect for any leaks after installation is complete.
View full procedure
Technical Service Bulletins

Fuel Rail Leakage Due to Improper Torque

2018-06-15

Some 2017-2019 Buick Lacrosse models may experience fuel rail leaks due to incorrect tightening of the mounting bolts. Symptoms may include fuel odor, fuel drips, or low fuel pressure codes.

2017-2019 Buick Lacrosse

Resolution: Inspect fuel rail bolts for proper torque. Retighten all fuel rail bolts to the correct specification of 18 ft-lbs (25 Nm) using a calibrated torque wrench. Inspect for leaks after installation.

Fuel Line Connector Overtightening Issue

2019-01-20

Instances of fuel line connection damage and leaks have been reported due to excessive tightening of fuel line connector bolts. This issue can damage the threads or deform the connection point, leading to leaks.

2017-2019 Buick Lacrosse

Resolution: Ensure fuel line connector bolts are torqued to 12 ft-lbs (16 Nm). Replace damaged fittings and fuel lines as needed. Always use a calibrated torque wrench to achieve correct torque.

About the Author

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Alan Montanye - Automotive Technical Specialist
ASE

Alan Montanye

Automotive Technical Specialist

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