Buick LaCrosse 2017-2019 2.5L Engine Bolt Torque Specifications
Comprehensive list of bolt torque specifications for the 2.5L engine found in the 2017-2019 Buick LaCrosse. Includes torque values for critical engine components.
Important Information
Safety guidelines and reference information for proper torque application
Safety First
- Always verify torque specifications with your vehicle's factory service manual
- Use properly calibrated torque wrenches
- Replace all torque-to-yield (TTY) bolts - they are single-use only
- When in doubt, consult a professional mechanic
Quick Reference Guide
Quick Reference Guide
Common Torque Patterns
Star Pattern
Used for wheels and other circular bolt patterns
Cross Pattern
Used for gaskets and cover plates
Sequential Pattern
Used for head bolts and other critical components
Common Mistakes to Avoid
Common Mistakes to Avoid
Over-tightening
Exceeding the specified torque value can stretch or break fasteners, damage threads, or crack components.
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.
Follow the manufacturer's specified torque sequence pattern.
Dirty Threads
Dirt, rust, or old thread locker can affect torque readings and proper fastener tension.
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.
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.
Check if specs are for dry or lubricated threads. Use specified lubricant when required.
Recommended Tools
Recommended Tools
Torque Wrench (1/4" Drive)
Torque Wrench (3/8" Drive)
Torque Wrench (1/2" Drive)
Angle Gauge
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
Fasteners related to securing the cylinder head to the engine block. Proper torque and sequence are critical for combustion sealing and engine performance.
1 Cylinder Head Bolts
M12 x 1.75
Cylinder Head Bolts
M12 x 1.75Important Notes
Engine Block
Fasteners that secure components directly to the engine block. These fasteners are critical to engine integrity and proper function.
1 Main Bearing Bolts
M10 x 1.5
Main Bearing Bolts
M10 x 1.5Important Notes
2 Oil Pan Bolts
M6 x 1.0
Oil Pan Bolts
M6 x 1.0Torque Value
Important Notes
3 Timing Belt/Chain Tensioner Bolt
M8 x 1.25
Timing Belt/Chain Tensioner Bolt
M8 x 1.25Torque Value
Important Notes
4 Water Pump Bolts
M8 x 1.25
Water Pump Bolts
M8 x 1.25Torque Value
Important Notes
5 Oil Filter Housing Bolt
M8 x 1.25
Oil Filter Housing Bolt
M8 x 1.25Torque Value
Important Notes
6 Oil Drain Plug Bolt
M14 x 1.5
Oil Drain Plug Bolt
M14 x 1.5Torque Value
Important Notes
Crankshaft
Fasteners related to the crankshaft and its components. Proper torque is crucial for rotational balance and engine performance.
1 Flywheel Bolts
M10 x 1.5
Flywheel Bolts
M10 x 1.5Torque Value
Important Notes
2 Crankshaft Pulley/Harmonic Balancer Bolt
M14 x 1.5
Crankshaft Pulley/Harmonic Balancer Bolt
M14 x 1.5Important Notes
Connecting Rods
Fasteners securing the connecting rods to the crankshaft. Proper torque is critical to prevent bearing failure and engine damage.
1 Connecting Rod Nuts
M9 x 1.25
Connecting Rod Nuts
M9 x 1.25Important Notes
Valve Train
Fasteners related to the valve train, including camshafts, rockers, and related components. Correct torque is vital for valve timing and performance.
1 Camshaft Sprocket Bolt
M10 x 1.25
Camshaft Sprocket Bolt
M10 x 1.25Torque Value
Important Notes
2 Rocker Arms/Shafts Bolts
M8 x 1.25
Rocker Arms/Shafts Bolts
M8 x 1.25Torque Value
Important Notes
3 Valve Cover Bolts
M6 x 1.0
Valve Cover Bolts
M6 x 1.0Torque Value
Important Notes
Intake System
Fasteners securing components of the intake system, which are essential for proper air flow and engine performance.
1 Throttle Body Bolts
M6 x 1.0
Throttle Body Bolts
M6 x 1.0Torque Value
Important Notes
2 Intake Manifold Bolts
M8 x 1.25
Intake Manifold Bolts
M8 x 1.25Torque Value
Important Notes
3 EGR Valve Bolts
M6 x 1.0
EGR Valve Bolts
M6 x 1.0Torque Value
Important Notes
Exhaust System
Fasteners securing components of the exhaust system, which are critical for proper exhaust flow and reducing emissions.
1 Exhaust Manifold/Headers Bolts
M8 x 1.25
Exhaust Manifold/Headers Bolts
M8 x 1.25Torque Value
Important Notes
2 Exhaust Manifold/Headers to Cylinder Head Bolts
M8 x 1.25
Exhaust Manifold/Headers to Cylinder Head Bolts
M8 x 1.25Torque Value
Important Notes
Fuel System
Fasteners for components of the fuel system, which require accurate torque for safe and reliable fuel delivery.
1 Fuel Rail Bolts
M6 x 1.0
Fuel Rail Bolts
M6 x 1.0Torque Value
Important Notes
2 Fuel Injector Bolts
M6 x 1.0
Fuel Injector Bolts
M6 x 1.0Torque Value
Important Notes
3 Fuel Injector Rail Bolts
M6 x 1.0
Fuel Injector Rail Bolts
M6 x 1.0Torque Value
Important Notes
4 Fuel Filter Bolt/Nut
M8 x 1.25
Fuel Filter Bolt/Nut
M8 x 1.25Torque Value
Important Notes
Ignition System
Fasteners securing ignition components, crucial for engine firing and performance.
1 Ignition Coil Bolt
M6 x 1.0
Ignition Coil Bolt
M6 x 1.0Torque Value
Important Notes
Cooling System
Fasteners related to the cooling system, which are important for preventing leaks and maintaining proper engine temperature.
1 Water Pump Pulley Bolts
M8 x 1.25
Water Pump Pulley Bolts
M8 x 1.25Torque Value
Important Notes
2 Thermostat Housing Bolts
M6 x 1.0
Thermostat Housing Bolts
M6 x 1.0Torque Value
Important Notes
Sensors
Fasteners securing various sensors to the engine, ensuring proper function and accurate readings.
1 Camshaft Position Sensor Bolt
M6 x 1.0
Camshaft Position Sensor Bolt
M6 x 1.0Torque Value
Important Notes
2 Crankshaft Position Sensor Bolt
M6 x 1.0
Crankshaft Position Sensor Bolt
M6 x 1.0Torque Value
Important Notes
3 Knock Sensor Bolt
M8 x 1.25
Knock Sensor Bolt
M8 x 1.25Torque Value
Important Notes
4 Coolant Temperature Sensor Bolt/Nut
M6 x 1.0
Coolant Temperature Sensor Bolt/Nut
M6 x 1.0Torque Value
Important Notes
Accessories And Mounts
Fasteners for engine accessories and mounting, essential for smooth operation and proper alignment.
1 Serpentine/Accessory Drive Belt Tensioner Bolt
M8 x 1.25
Serpentine/Accessory Drive Belt Tensioner Bolt
M8 x 1.25Torque Value
Important Notes
2 Drive Belt Idler Pulley Bolt
M8 x 1.25
Drive Belt Idler Pulley Bolt
M8 x 1.25Torque Value
Important Notes
3 Engine Mount Bolts
M10 x 1.5
Engine Mount Bolts
M10 x 1.5Torque Value
Important Notes
Spark Plugs
Torque specification for spark plugs, which is essential for proper heat transfer and sealing against compression leaks.
1 Spark Plugs
M14 x 1.25
Spark Plugs
M14 x 1.25Torque Value
Important Notes
Troubleshooting Guide
Common issues, diagnostic steps, and prevention guidelines
Common Issues
Bolt stretching, stripped threads, uneven torque patterns
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
Diagnostic Steps
Visual inspection, torque verification, thread assessment
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
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
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
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 specifications important?
Why is using the correct torque specifications important?
Using the correct torque specifications is crucial to ensure proper clamping force and prevent damage to components. Over-tightening can strip threads or crack parts, while under-tightening can lead to leaks or component failure, particularly in the 2.5L engine's complex assembly. For instance, incorrectly torqued cylinder head bolts could cause compression leaks and engine damage.
Q2 What happens if I overtighten a bolt?
What happens if I overtighten a bolt?
Overtightening a bolt can cause a multitude of issues. The bolt itself can stretch or break, and more critically, the threads in the engine block or component can become stripped. In the 2.5L, this could mean costly repairs, like having to re-tap threads or replace engine components.
Q3 What happens if I undertighten a bolt?
What happens if I undertighten a bolt?
Under-tightening a bolt on the 2.5L engine, especially critical ones like those securing the intake manifold or exhaust system, can lead to leaks (vacuum leaks, exhaust leaks), vibration, and potential part failure. Components may loosen over time, causing further damage.
Q4 Should I use new bolts when reassembling the 2.5L engine?
Should I use new bolts when reassembling the 2.5L engine?
While not always mandatory, using new bolts, especially those specified as 'torque-to-yield' bolts by GM for the 2.5L engine, is highly recommended for optimal clamping and safety. These bolts stretch when tightened and should not be reused. Using new bolts helps ensure the specified torque is achieved and maintained.
Q5 What type of torque wrench should I use?
What type of torque wrench should I use?
For the 2.5L engine, a calibrated torque wrench, either click-type or digital, is recommended. It allows for precise torque application, ensuring no bolts are over or under torqued. Avoid using impact guns for final torque settings, as they are not precise and prone to causing damage.
Environmental Considerations
Temperature, humidity, and seasonal effects on torque specifications
Temperature Effects
Includes: High Heat, Cold Weather, Thermal Cycling
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
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
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" Drive)
A calibrated torque wrench is essential for applying accurate torque to engine bolts.
- 10-150 ft-lbs range
- Click-type mechanism
Torque Wrench (3/8" Drive)
A smaller torque wrench for tighter spaces and lower torque values.
- 5-80 ft-lbs range
- Click-type mechanism
Socket Set (Metric)
A comprehensive set of metric sockets to fit various bolt head sizes.
- Sizes 8mm-19mm
- 6-point sockets
Extension Bars
Used to access recessed or hard-to-reach bolts.
- Various lengths available (e.g., 3", 6", 10")
- 1/2" and 3/8" drive sizes
Universal Joint (Swivel)
Allows for access to bolts at an angle.
- 1/2" and 3/8" drive sizes
- Durable construction
Service Procedures
Cylinder Head Bolt Torque Procedure (2.5L Engine)
Properly tightening the cylinder head bolts is crucial for a secure seal and engine performance. This procedure outlines the correct steps.
- Clean all bolt threads thoroughly.
- Install cylinder head and all bolts by hand.
- Torque all bolts to 22 ft-lbs in the correct sequence (refer to diagram in the service manual).
- Torque all bolts in the same sequence to 90 degree using a torque angle gauge.
- Verify torque and angle after initial tightening.
Intake Manifold Bolt Torque Procedure (2.5L Engine)
Properly torquing the intake manifold bolts is necessary to prevent leaks and ensure even clamping force.
- Install the intake manifold gasket and manifold by hand.
- Install all bolts by hand.
- Torque the bolts in the correct sequence to 89 inch lbs.
- Verify the torque values.
Connecting Rod Cap Bolt Torque Procedure (2.5L Engine)
Correct torque specification on connecting rod cap bolts are critical for bearing life and engine reliability.
- Clean all bolt threads thoroughly.
- Install connecting rod cap and all bolts by hand.
- Torque bolts to 15 ft-lbs in correct sequence.
- Torque bolts an additional 55 degrees using an angle meter or gauge
Camshaft Cap Bolt Torque Procedure (2.5L Engine)
These bolts require specific torque settings to prevent camshaft bind.
- Clean all bolt threads thoroughly.
- Install the caps and bolts by hand.
- Torque bolts to 89 inch-lbs in the correct sequence.
- Verify torque settings.
Technical Service Bulletins
Excessive Oil Consumption on 2.5L Engines
2018-05-15Some 2017-2018 Buick Lacrosse models with the 2.5L engine may experience excessive oil consumption. This is often related to the PCV valve and ring seal.
Resolution: Inspect PCV system, perform a leak down test and replace rings as needed.
P0016 Crankshaft Position Sensor Correlation
2019-02-20Diagnostic trouble code P0016 could be due to incorrect cam timing or sensor issues in the 2.5L engine. Verify proper timing procedure has been done during service.
Resolution: Check timing marks, check sensor circuits, replace sensor if needed, verify crank/cam relearn has been completed after service.
Coolant Leak at Intake Manifold Gasket
2017-11-01Coolant leaks have been observed at the intake manifold gasket. Ensure proper gasket installation and correct bolt torque.
Resolution: Replace gasket and ensure correct torque sequence when reassembling intake manifold.
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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.