Troy-Bilt TB635EC Problems

The Troy-Bilt TB635EC is a versatile and powerful gas-powered string trimmer designed to tackle even the toughest yard maintenance tasks. However, like any outdoor power equipment, it may encounter problems over time due to wear and tear or improper use.

This comprehensive guide will explore common issues that users may face with the Troy-Bilt TB635EC and provide detailed troubleshooting steps to help you get your trimmer back in working order. Whether you’re dealing with starting problems, cutting issues, or other concerns, this guide will assist you in diagnosing and resolving the most common problems associated with this trimmer.

Understanding the Troy-Bilt TB635EC

Before we delve into specific problems and their solutions, it’s essential to have a basic understanding of the Troy-Bilt TB635EC string trimmer. This powerful machine features a two-cycle engine that runs on a mixture of gasoline and oil. It is equipped with a cutting head that utilizes a nylon string to trim grass and weeds efficiently. Understanding the key components and how they work together will be helpful in diagnosing and fixing issues that may arise during operation.

Common Troy-Bilt TB635EC Problems

  1. Starting Problems:
    • Symptoms: Difficulty starting the trimmer, engine not turning over, or inconsistent starting.
    • Causes: Old or stale fuel, spark plug issues, clogged air filter, or a malfunctioning primer bulb.
    • Troubleshooting: Ensure you are using fresh fuel mix, replace the spark plug, clean or replace the air filter, and inspect the primer bulb for cracks or damage.
  2. Idle and Running Issues:
    • Symptoms: The trimmer idles roughly, stalls frequently, or lacks power during operation.
    • Causes: Clogged carburetor, fuel line problems, or a dirty or worn-out spark arrestor screen.
    • Troubleshooting: Clean the carburetor, check fuel lines for blockages or leaks, and inspect and clean the spark arrestor screen.
  3. Cutting Problems:
    • Symptoms: The trimmer line doesn’t advance or feed properly, or it breaks frequently.
    • Causes: Worn or tangled trimmer line, improperly wound spool, or damaged cutting head.
    • Troubleshooting: Replace or rewind the trimmer line correctly, and inspect the cutting head for damage.
  4. Overheating or Smoking:
    • Symptoms: Excessive heat or smoke coming from the engine.
    • Causes: Overloading the trimmer, incorrect fuel mixture, or insufficient oil lubrication.
    • Troubleshooting: Avoid overloading the trimmer, ensure the correct fuel mixture, and check for proper oil lubrication.
  5. Excessive Vibration:
    • Symptoms: Unusual levels of vibration during operation.
    • Causes: Loose or damaged cutting head, bent drive shaft, or worn bearings.
    • Troubleshooting: Tighten the cutting head and inspect the drive shaft and bearings for damage.

Troy-Bilt TB635EC Problems

Troubleshooting Steps

Now that you’re familiar with common Troy-Bilt TB635EC problems, let’s explore troubleshooting steps to help you address these issues effectively:

  1. Starting Troubleshooting:
    • Ensure the spark plug is clean and properly gapped.
    • Check the primer bulb for cracks or damage.
    • Use fresh fuel mix with the correct oil-to-gas ratio.
    • Clean or replace the air filter.
  2. Idle and Running Troubleshooting:
    • Clean the carburetor to remove any clogs.
    • Inspect and replace fuel lines if necessary.
    • Clean or replace the spark arrestor screen.
    • Adjust the carburetor settings following the trimmer’s manual.
  3. Cutting Troubleshooting:
    • Rewind or replace the trimmer line, following the manufacturer’s instructions.
    • Inspect the cutting head for damage, and replace if needed.
  4. Overheating or Smoking Troubleshooting:
    • Avoid overloading the trimmer; take breaks during extended use.
    • Ensure the correct fuel mixture (usually a 50:1 ratio of gasoline to 2-cycle oil).
    • Check for proper oil lubrication; refill if necessary.
  5. Excessive Vibration Troubleshooting:
    • Tighten the cutting head securely.
    • Inspect the drive shaft for bends or damage; replace if required.
    • Check the bearings for wear and replace if needed.

Preventive Maintenance

To keep your Troy-Bilt TB635EC in excellent working condition and prevent problems from arising, consider the following preventive maintenance tips:

  • Follow the manufacturer’s recommended maintenance schedule for oil changes, spark plug replacements, and air filter cleaning or replacements.
  • Always use fresh, high-quality gasoline mixed with the appropriate 2-cycle oil at the correct ratio.
  • Store the trimmer in a cool, dry place and keep it clean to prevent dirt and debris buildup.
  • Regularly inspect and clean the cutting head, trimmer line, and spark arrestor screen.
  • Lubricate any moving parts as specified in the owner’s manual.


The Troy-Bilt TB635EC is a reliable and powerful string trimmer that can make yard maintenance tasks more manageable. However, as with any machine, it may encounter issues from time to time. By understanding common problems and following the troubleshooting steps outlined in this guide, you can keep your trimmer in peak operating condition. Regular maintenance and prompt attention to any problems will ensure that your Troy-Bilt TB635EC continues to serve you well, making your yard work more efficient and enjoyable.

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