Stihl HT 135 Problems Solved (5 Pro Arborist Fixes)

The Stihl HT 135: Taming the Troubles of a Telescopic Titan (5 Pro Arborist Fixes)

Before we dive into the nitty-gritty of troubleshooting your Stihl HT 135 pole saw, let’s acknowledge the often-overlooked health benefits of working with wood. I’ve always found that the physical labor involved in processing wood, whether it’s felling a tree or splitting logs, is incredibly therapeutic. It’s a full-body workout that gets you out in the fresh air, away from screens, and connected to nature. Beyond the physical, there’s a mental clarity that comes from the rhythmic, repetitive motions of the work. It’s a fantastic stress reliever, and the satisfaction of turning raw wood into something useful is deeply rewarding. Now, with our minds and bodies primed for action, let’s tackle those HT 135 challenges!

I understand the frustration when a vital tool like the Stihl HT 135 lets you down. This telescopic pole saw is a workhorse for arborists and homeowners alike, allowing us to reach high branches with relative ease. But like any machine, it can develop problems. Over the years, I’ve encountered my fair share of HT 135 issues, from starting difficulties to lackluster cutting performance. Through trial and error, and a lot of late nights in the workshop, I’ve developed a set of reliable fixes that I want to share with you. These aren’t just quick patches; they’re solutions based on understanding the machine’s mechanics and anticipating common wear points.

Understanding the Stihl HT 135: A Brief Overview

The Stihl HT 135 is a gasoline-powered pole saw designed for pruning and tree maintenance. Its key features include:

• Telescopic Shaft: Extends for increased reach.
• 2-MIX Engine: Offers a good balance of power and fuel efficiency.
• Lightweight Design: Improves maneuverability and reduces fatigue.
• Automatic Chain Lubrication: Ensures smooth cutting.

Knowing these components is crucial for diagnosing problems effectively.

Problem 1: The Stubborn Start – Engine Refusal to Ignite

This is a common complaint and often the most frustrating. You pull and pull, but the engine refuses to roar to life. Here’s my methodical approach to tackling this issue:

Fuel System Inspection

• The Fuel Filter: This small component is often the culprit. Over time, it can become clogged with debris, restricting fuel flow.
  • Action: Locate the fuel filter inside the fuel tank. It’s usually attached to the fuel line. Use a small hook or bent wire to pull it out. Inspect it closely. If it’s dirty or discolored, replace it. I recommend replacing it annually as preventative maintenance.
  • Tool List: Small hook or bent wire, replacement fuel filter (Stihl part number is readily available online).
  • Tip: When replacing the fuel filter, make sure the fuel line is securely attached. A loose connection can introduce air into the fuel system.
• The Fuel Line: Cracks or leaks in the fuel line can also prevent the engine from starting.
  • Action: Carefully inspect the fuel line for any signs of damage. Pay close attention to the areas where the line connects to the fuel tank and carburetor. If you find any cracks or leaks, replace the fuel line.
  • Tool List: Screwdriver, replacement fuel line (Stihl part number).
  • Experience: I once spent hours troubleshooting a starting problem, only to discover a tiny pinhole leak in the fuel line. It was almost invisible, but it was enough to prevent the engine from drawing fuel properly.
• The Carburetor: This component mixes fuel and air to create a combustible mixture. If the carburetor is clogged or dirty, it can prevent the engine from starting.
  • Action: Remove the air filter and spray carburetor cleaner into the carburetor throat. Then, try starting the engine. If it starts briefly and then dies, the carburetor is likely clogged.
  • Tool List: Carburetor cleaner, screwdriver.
  • Caution: Carburetor cleaner is flammable. Use it in a well-ventilated area and avoid spraying it near open flames or sparks.
  • Advanced Action: If cleaning the carburetor doesn’t solve the problem, you may need to rebuild it. This involves disassembling the carburetor, cleaning all the parts, and replacing any worn or damaged components. Carburetor rebuild kits are available online and at most small engine repair shops. I’ve rebuilt dozens of carburetors, and it’s a skill that has saved me a lot of money over the years.

Ignition System Check

• The Spark Plug: A faulty spark plug can prevent the engine from starting.
  • Action: Remove the spark plug and inspect it. Look for signs of fouling (carbon buildup), cracking, or damage. If the spark plug is fouled, clean it with a wire brush or replace it. If the spark plug is cracked or damaged, replace it.
  • Tool List: Spark plug wrench, wire brush, replacement spark plug (Stihl part number).
  • Specification: The correct spark plug gap for the Stihl HT 135 is typically 0.020 inches (0.5 mm). Use a spark plug gapping tool to ensure the gap is correct.
• The Ignition Coil: The ignition coil generates the high-voltage spark that ignites the fuel-air mixture. If the ignition coil is faulty, it can prevent the engine from starting.
  • Action: Use a spark tester to check the ignition coil. Connect the spark tester to the spark plug wire and ground the tester. Pull the starter rope. If the spark tester doesn’t produce a spark, the ignition coil is likely faulty and needs replacing.
  • Tool List: Spark tester, screwdriver, replacement ignition coil (Stihl part number).
  • Safety Note: When testing the ignition coil, be careful not to touch the spark plug wire. The voltage is very high and can cause a painful shock.

Compression Test

• The Cylinder: Low compression can also cause starting problems.
  • Action: Use a compression tester to check the cylinder compression. Remove the spark plug and screw the compression tester into the spark plug hole. Pull the starter rope several times. The compression reading should be within the manufacturer’s specifications.
  • Tool List: Compression tester.
  • Specification: The minimum compression for the Stihl HT 135 is typically around 100 PSI. If the compression is below this level, the engine may need to be rebuilt.
  • Insight: I once worked on an HT 135 with incredibly low compression. The culprit? A worn piston ring. Replacing the piston ring restored the compression and brought the engine back to life.

Takeaway: A systematic approach to fuel, ignition, and compression is key to diagnosing and fixing starting problems. Don’t jump to conclusions; test each component methodically.

Problem 2: Chain Oil Issues – Lack of Lubrication

A properly lubricated chain is essential for efficient cutting and preventing premature wear. Insufficient chain oil can lead to overheating, chain breakage, and damage to the guide bar.

Oil Tank and Line Inspection

• The Oil Tank: Ensure the oil tank is filled with the correct type of chain oil. I recommend using Stihl chain oil or a high-quality bar and chain oil specifically designed for chainsaws.
  • Action: Visually inspect the oil tank for cracks or leaks. If you find any damage, replace the tank.
  • Tip: Avoid using old or contaminated oil. This can clog the oil pump and prevent proper lubrication.
• The Oil Line: Check the oil line for kinks, cracks, or blockages.
  • Action: Disconnect the oil line from the oil pump and the oil tank. Blow compressed air through the line to clear any blockages. If the line is damaged, replace it.
  • Tool List: Compressed air, screwdriver, replacement oil line (Stihl part number).

Oil Pump Problems

• The Oil Pump: The oil pump is responsible for delivering oil to the chain. If the oil pump is faulty, it can prevent the chain from being properly lubricated.
  • Action: Remove the oil pump and inspect it for damage or wear. Check the pump’s gears and piston for any signs of wear. If the pump is damaged, replace it.
  • Tool List: Screwdriver, replacement oil pump (Stihl part number).
  • Experience: I once had an HT 135 where the oil pump was completely clogged with sawdust. It took me a while to clean it out, but once I did, the oil flow was restored.
• The Oil Pump Adjustment: Some HT 135 models have an adjustable oil pump. If the oil pump is not properly adjusted, it may not be delivering enough oil to the chain.
  • Action: Consult the owner’s manual for instructions on how to adjust the oil pump. Increase the oil flow until the chain is adequately lubricated.
  • Tip: When adjusting the oil pump, start with a low setting and gradually increase the flow until you reach the desired level.

Guide Bar Groove Cleaning

• The Guide Bar: The guide bar groove can become clogged with sawdust and debris, preventing oil from reaching the chain.
  • Action: Use a guide bar cleaner or a small screwdriver to clean the guide bar groove. Remove all sawdust and debris.
  • Tool List: Guide bar cleaner or small screwdriver.
  • Frequency: I recommend cleaning the guide bar groove every time you sharpen the chain.

Takeaway: Consistent oiling is crucial. Regularly inspect the oil tank, lines, and pump. Clean the guide bar groove frequently.

Problem 3: Chain Slippage and Poor Cutting Performance

A dull or improperly tensioned chain will significantly reduce cutting efficiency and can even be dangerous. Here’s how to sharpen and tension your chain properly:

Chain Sharpening

• The Chain Sharpness: A sharp chain is essential for efficient cutting. A dull chain will require more effort to cut through wood and can increase the risk of kickback.
  • Action: Use a chainsaw file and a filing guide to sharpen the chain. Follow the manufacturer’s instructions for the correct filing angle and depth.
  • Tool List: Chainsaw file, filing guide, depth gauge tool.
  • Specification: The correct filing angle for the Stihl HT 135 chain is typically 30 degrees. The depth gauge setting should be slightly below the top of the cutter. Refer to your manual for exact specs.
  • Alternative: If you’re not comfortable sharpening the chain yourself, you can take it to a professional sharpening service.
  • Insight: I invested in a good quality chainsaw sharpener years ago, and it’s been one of the best investments I’ve made. It saves me time and ensures that my chains are always sharp.
• Chain Damage: Inspect the chain for any signs of damage, such as broken or missing teeth. If the chain is damaged, replace it.
  • Tool List: Replacement chain (Stihl part number).

Chain Tensioning

• The Chain Tension: Proper chain tension is crucial for safe and efficient cutting. A chain that is too loose can come off the guide bar, while a chain that is too tight can overheat and break.
  • Action: Loosen the bar nuts and adjust the chain tension using the tensioning screw. The chain should be snug against the guide bar, but you should still be able to pull it around the bar by hand.
  • Tool List: Wrench, screwdriver.
  • Procedure: With the engine off and the saw unplugged, loosen the bar nuts slightly. Then, using a screwdriver, turn the chain tensioning screw until the chain is snug against the guide bar. Tighten the bar nuts securely.
  • Tip: Check the chain tension frequently, especially when the chain is new. New chains tend to stretch during the first few uses.
  • Experience: I learned the importance of proper chain tension the hard way. I once had a chain come off the guide bar while I was cutting a branch overhead. Luckily, I wasn’t injured, but it was a close call.

Guide Bar Condition

• The Guide Bar: A worn or damaged guide bar can also contribute to chain slippage and poor cutting performance.
  • Action: Inspect the guide bar for wear, damage, or burrs. If the guide bar is worn or damaged, replace it.
  • Tool List: File, replacement guide bar (Stihl part number).
  • Maintenance: Use a file to remove any burrs or sharp edges from the guide bar. Flip the guide bar periodically to ensure even wear.

Takeaway: Sharpen your chain regularly, maintain proper tension, and inspect your guide bar. These three steps will dramatically improve cutting performance and extend the life of your saw.

Problem 4: Overheating Engine

An overheating engine can lead to serious damage. Understanding the causes and implementing preventative measures is essential.

Air Intake and Cooling Fins

• The Air Filter: A clogged air filter can restrict airflow to the engine, causing it to overheat.
  • Action: Remove the air filter and clean it with soap and water. Allow the air filter to dry completely before reinstalling it. If the air filter is damaged, replace it.
  • Tool List: Soap, water, replacement air filter (Stihl part number).
  • Frequency: I recommend cleaning the air filter every time you use the saw.
• The Cooling Fins: The cooling fins on the engine cylinder help to dissipate heat. If the cooling fins are clogged with debris, the engine can overheat.
  • Action: Use a brush or compressed air to clean the cooling fins. Remove all debris.
  • Tool List: Brush, compressed air.
  • Caution: Be careful not to damage the cooling fins when cleaning them.

Fuel Mixture Issues

• The Fuel Mixture: Using the wrong fuel mixture can also cause the engine to overheat. The Stihl HT 135 requires a specific fuel-to-oil ratio.
  • Action: Use the correct fuel-to-oil ratio. The recommended ratio for the Stihl HT 135 is typically 50:1 (50 parts gasoline to 1 part oil). Use a high-quality two-stroke oil specifically designed for chainsaws.
  • Tip: Use a fuel mixture chart or a fuel mixing bottle to ensure that you are using the correct ratio.
  • Danger: Never use straight gasoline in the Stihl HT 135. This will cause the engine to overheat and seize.
• Fuel Quality: Old or stale fuel can cause engine problems, including overheating.
  • Action: Use fresh fuel. Fuel that has been sitting for more than 30 days can start to degrade. If you’re not going to use the saw for a while, drain the fuel tank and carburetor.

Engine Load

• Excessive Load: Forcing the saw to cut through wood too quickly can cause the engine to overheat.
  • Action: Let the saw do the work. Don’t force it. Use a sharp chain and apply gentle pressure.
  • Technique: Avoid burying the guide bar in the wood. This can put excessive strain on the engine.

Takeaway: Keep the air filter clean, use the correct fuel mixture, and avoid overloading the engine. These simple steps can prevent overheating and extend the life of your saw.

Problem 5: Telescopic Shaft Issues – Sticking or Failure to Extend/Retract

The telescopic shaft is what gives the HT 135 its reach, so any issues here severely limit its functionality.

Cleaning and Lubrication

• The Locking Mechanism: The locking mechanism on the telescopic shaft can become stiff or difficult to operate if it is dirty or dry.
  • Action: Clean the locking mechanism with a brush and lubricate it with a light oil or silicone spray.
  • Tool List: Brush, light oil or silicone spray.
  • Frequency: I recommend cleaning and lubricating the locking mechanism every time you use the saw.
• The Shaft Sections: The shaft sections can also become stuck if they are dirty or dry.
  • Action: Clean the shaft sections with a damp cloth and lubricate them with a light oil or silicone spray.
  • Tool List: Damp cloth, light oil or silicone spray.
  • Tip: Avoid using excessive amounts of oil or grease. This can attract dirt and debris.

Damage Inspection

• The Shaft Sections: Inspect the shaft sections for any signs of damage, such as dents or bends. If the shaft sections are damaged, they may need to be replaced.
  • Tool List: Replacement shaft sections (Stihl part number).
• The Locking Mechanism: Inspect the locking mechanism for any signs of damage, such as cracks or broken parts. If the locking mechanism is damaged, it may need to be replaced.
  • Tool List: Replacement locking mechanism (Stihl part number).

Adjustment

• The Locking Mechanism Adjustment: Some telescopic shafts have an adjustable locking mechanism. If the locking mechanism is not properly adjusted, it may not hold the shaft sections securely in place.
  • Action: Consult the owner’s manual for instructions on how to adjust the locking mechanism. Tighten or loosen the locking mechanism until the shaft sections are held securely in place.

Takeaway: Regular cleaning and lubrication are key to maintaining a smooth-operating telescopic shaft. Inspect the shaft and locking mechanism for damage and adjust as needed.

General Maintenance Tips for Long-Term Reliability

Beyond addressing specific problems, a proactive maintenance routine is essential for keeping your Stihl HT 135 running smoothly for years to come.

• Regular Cleaning: Clean the saw after each use. Remove sawdust and debris from the engine, air filter, and chain.
• Proper Storage: Store the saw in a dry, protected location. Drain the fuel tank and carburetor before storing the saw for extended periods.
• Scheduled Servicing: Follow the manufacturer’s recommended service schedule. This includes replacing the spark plug, fuel filter, and air filter at regular intervals.
• Chain Maintenance: Keep the chain sharp and properly tensioned.
• Fuel and Oil: Use only high-quality fuel and oil specifically designed for two-stroke engines.
• Safety Gear: Always wear appropriate safety gear, including eye protection, hearing protection, gloves, and sturdy footwear.
• Read the Manual: Familiarize yourself with the owner’s manual and follow the manufacturer’s instructions for operation and maintenance.

Unique Insights and Personal Experiences

Over the years, I’ve learned a few tricks that aren’t always found in the owner’s manual:

• Use Synthetic Oil: I switched to using synthetic two-stroke oil in my HT 135 a few years ago, and I’ve noticed a significant improvement in engine performance and longevity. Synthetic oil provides better lubrication and reduces carbon buildup.
• Stabilize Fuel: If I know I’m not going to be using the saw for a while, I add a fuel stabilizer to the fuel tank. This prevents the fuel from degrading and causing problems.
• Check the Clutch: The clutch is a critical component that transfers power from the engine to the chain. Periodically inspect the clutch shoes for wear. If the clutch shoes are worn, replace them.
• Listen to Your Saw: Pay attention to the sound of your saw. Unusual noises can be a sign of a problem. If you hear anything that doesn’t sound right, stop using the saw and investigate.

Case Study: Reviving a Neglected HT 135

I once acquired a Stihl HT 135 that had been neglected for years. It was covered in dirt and grime, the chain was dull, and the engine wouldn’t start. I spent a few hours cleaning the saw, sharpening the chain, and troubleshooting the engine. I replaced the fuel filter, spark plug, and air filter. I also cleaned the carburetor and adjusted the chain tension. After all that work, the saw started right up and ran like new. It was a satisfying experience to bring a neglected tool back to life.

The Importance of Safety

Before I conclude, I must stress the importance of safety when working with a pole saw. Always wear appropriate safety gear, including a helmet, eye protection, hearing protection, gloves, and sturdy footwear. Be aware of your surroundings and maintain a safe distance from other people and objects. Never operate the saw while standing on a ladder or in an unstable position. And always follow the manufacturer’s instructions for operation and maintenance.

Conclusion: Mastering Your HT 135

The Stihl HT 135 is a valuable tool for any arborist or homeowner who needs to reach high branches. By understanding the common problems that can occur and following the troubleshooting steps I’ve outlined, you can keep your HT 135 running smoothly for years to come. Remember, regular maintenance, proper chain care, and a focus on safety are key to maximizing the performance and longevity of your saw. And, while you’re at it, take a moment to appreciate the health benefits of working with wood. The physical activity, mental clarity, and sense of accomplishment are all valuable rewards for your efforts. Now, go forth and conquer those high branches!

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