Mercedes-Benz Mercedes CLA 2013-2019 Electrical System Bolt Torque Specifications & Ground Points
Mercedes-Benz Mercedes CLA 2013-2019

Mercedes-Benz Mercedes CLA 2013-2019 Electrical System Bolt Torque Specifications

Detailed torque specifications for electrical bolts in the 2013-2019 Mercedes-Benz CLA, including battery terminals, alternator bolts, and grounding points.

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

Electrical system mounting

Components that secure electrical system components to the engine block or other structural elements.

1

Alternator Mounting Bolts

M12 x 1.5
Torque Value
18 ft-lbs (24 N·m)
Important Notes
Proper torque ensures the alternator is securely fastened to the engine block.
2

Starter Motor Mounting Bolts

M14 x 1.5
Torque Value
30 ft-lbs (40 N·m)
Important Notes
Proper torque ensures the starter motor is securely fastened to the engine block.

Electrical connectors

Components that secure electrical connections between components.

1

Battery Terminal Nuts

M8 x 1.25
Torque Value
7 ft-lbs (10 N·m)
Important Notes
Proper torque prevents loose connections that can cause electrical system malfunctions.
2

Ignition Coil Mounting Bolts

M10 x 1.5
Torque Value
10 ft-lbs (14 N·m)
Important Notes
Estimated value based on general industry guidelines. Proper torque ensures the coil is securely fastened to the engine.
3

Fuel Pump Electrical Connector Bolts

M6 x 1.0
Torque Value
5 ft-lbs (7 N·m)
Important Notes
Estimated value based on general industry guidelines. Proper torque ensures a reliable electrical connection.
4

A/C Compressor Electrical Connector Bolts

M6 x 1.0
Torque Value
5 ft-lbs (7 N·m)
Important Notes
Estimated value based on general industry guidelines. Proper torque ensures a reliable electrical connection.

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 is the torque specification for the battery terminal bolts on a 2013-2019 Mercedes CLA?

The torque specification for the battery terminal bolts is typically 5 Nm (44 in-lb). Always refer to the vehicle's service manual for exact specifications, as improper torque can lead to electrical issues or damage.

Q2

How often should I check the torque on electrical connections in my Mercedes CLA?

It is recommended to check the torque on critical electrical connections, such as battery terminals and grounding points, during routine maintenance or if you experience electrical issues. Loose connections can cause poor performance or system failures.

Q3

Can over-tightening electrical bolts cause damage?

Yes, over-tightening can strip threads, crack components, or damage electrical terminals, leading to poor conductivity or system failure. Always use a calibrated torque wrench and follow manufacturer specifications.

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

Digital Torque Wrench

A precision tool for applying accurate torque to electrical bolts.

  • Adjustable torque settings
  • LCD display for real-time torque readings
Learn more

Insulated Socket Set

A set of sockets designed for electrical work to prevent short circuits.

  • Non-conductive materials
  • Multiple socket sizes for various bolt types
Learn more

Torque Angle Gauge

A tool to measure the angle of rotation when tightening bolts.

  • Digital angle measurement
  • Magnetic base for easy attachment
Learn more
Service Procedures

Torque Application for Battery Terminal Bolts

Procedure for applying the correct torque to battery terminal bolts to ensure secure connections.

  • Disconnect the negative battery terminal.
  • Clean the battery terminals and bolts.
  • Apply the specified torque using a digital torque wrench.
  • Reconnect the negative terminal and test the connection.
View full procedure

Torque Application for Alternator Mounting Bolts

Procedure for tightening alternator mounting bolts to the manufacturer's specifications.

  • Locate the alternator and identify the mounting bolts.
  • Use an insulated socket set to loosen the bolts.
  • Apply the specified torque using a torque wrench.
  • Verify the alternator is securely mounted.
View full procedure

Torque Application for Grounding Points

Procedure for ensuring proper torque on grounding points to maintain electrical system integrity.

  • Identify all grounding points in the electrical system.
  • Clean the grounding points and bolts.
  • Apply the specified torque using a torque wrench.
  • Test the grounding points for continuity.
View full procedure
Technical Service Bulletins

Electrical System Bolt Torque Specifications Update

2017-05-15

Updated torque specifications for electrical system bolts to prevent over-tightening and damage.

2013-2019 Mercedes CLA

Resolution: Refer to the updated torque specifications in the service manual and use a calibrated torque wrench for all electrical bolt applications.

Battery Terminal Corrosion Prevention

2018-08-22

Technical bulletin addressing battery terminal corrosion due to improper torque application.

2013-2019 Mercedes CLA

Resolution: Ensure proper torque is applied to battery terminal bolts and apply anti-corrosion gel to prevent future issues.

Alternator Mounting Bolt Failure

2019-03-10

Bulletin regarding alternator mounting bolt failures caused by incorrect torque application.

2013-2019 Mercedes CLA

Resolution: Replace any damaged bolts and apply the correct torque using a calibrated torque wrench.

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.

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