Stihl MS 291 Problems (5 Key Engine Tips)

The Stihl MS 291 is a workhorse, a testament to German engineering, and a favorite among both seasoned loggers and weekend warriors tackling firewood prep. But even the best machines can face hiccups. As someone who’s spent countless hours felling trees and splitting wood, I’ve encountered my share of chainsaw problems. I’ve learned that understanding the common issues with the Stihl MS 291, especially those related to the engine, can save you a lot of frustration, downtime, and, most importantly, money. This article dives deep into five key engine tips to keep your MS 291 roaring and your woodpile growing.

Stihl MS 291 Problems (5 Key Engine Tips)

The Stihl MS 291 is renowned for its reliability, but like any internal combustion engine, it’s susceptible to issues. Ignoring these can lead to costly repairs or even complete engine failure. My aim is to provide you with proactive tips and tricks to diagnose and address potential problems before they escalate.

1. Fuel System Follies: Ensuring Proper Fuel Delivery

The fuel system is the lifeline of your MS 291. If it’s compromised, your saw won’t run, will run poorly, or will be difficult to start.

The Carburetor Conundrum

The carburetor is the heart of the fuel system, responsible for mixing air and fuel in the correct ratio for combustion. A dirty or improperly adjusted carburetor is a common culprit for starting problems, rough idling, and poor performance.

• Symptoms: Hard starting, stalling, erratic idling, lack of power, black smoke from the exhaust.
• Troubleshooting:
  • Fuel Quality: Always use fresh, high-quality fuel with the correct oil mix ratio (typically 50:1 for the MS 291). Stale fuel can gum up the carburetor’s tiny passages. I made the mistake once of using fuel that was sitting in my garage for almost a year. The saw refused to start, and it took a complete carburetor cleaning to get it running again. Now, I only use fuel that’s less than a month old, and I add a fuel stabilizer if I know it will be sitting for a while.
  • Air Filter: A dirty air filter restricts airflow, leading to a rich fuel mixture (too much fuel, not enough air). Clean or replace the air filter regularly.
  • Carburetor Adjustment: The MS 291 carburetor typically has three adjustment screws: L (Low speed), H (High speed), and LA (Idle speed). Adjusting these screws requires a special tool and a good understanding of engine tuning. Unless you are experienced, it’s best to consult a professional. I once tried to adjust the carburetor on my own without the proper tools and ended up making the problem worse.
  • Cleaning: If the carburetor is dirty, you’ll need to clean it. This involves disassembling the carburetor, soaking the parts in carburetor cleaner, and using compressed air to blow out any debris. Carburetor rebuild kits are readily available and relatively inexpensive.
• Cost Considerations:
  • Carburetor cleaner: \$5 – \$15
  • Carburetor rebuild kit: \$10 – \$30
  • Professional carburetor cleaning/adjustment: \$50 – \$100

Fuel Lines and Filter Foibles

The fuel lines and filter ensure a clean and steady flow of fuel to the carburetor. Cracked or clogged fuel lines and a dirty fuel filter can starve the engine of fuel.

• Symptoms: Hard starting, stalling, lack of power, engine cutting out at high RPMs.
• Troubleshooting:
  • Visual Inspection: Check the fuel lines for cracks, leaks, or kinks. Replace any damaged lines.
  • Fuel Filter: Remove the fuel filter from the fuel tank and inspect it. If it’s dirty, replace it. Fuel filters are inexpensive and should be replaced regularly. I usually replace mine every season, or more often if I’m cutting in dusty conditions.
• Cost Considerations:
  • Fuel filter: \$3 – \$8
  • Fuel line replacement: \$10 – \$20 (for parts)

Fuel Tank Vent Troubles

The fuel tank vent allows air to enter the fuel tank as fuel is consumed. A clogged vent can create a vacuum in the tank, preventing fuel from flowing to the carburetor.

• Symptoms: Engine starts and runs for a short time, then stalls.
• Troubleshooting:
  • Loosen the Fuel Cap: If the engine runs with the fuel cap slightly loosened, the vent is likely clogged.
  • Clean the Vent: Locate the fuel tank vent and clean it with compressed air or a small wire.
• Cost Considerations:
  • Fuel tank vent replacement: \$5 – \$15

Data Points & Statistics:

• According to a survey of chainsaw repair shops in the US, fuel-related problems account for approximately 40% of chainsaw repairs.
• The average cost of repairing a chainsaw fuel system is between \$75 and \$150.

2. Ignition System Insights: Sparking the Combustion

The ignition system is responsible for creating the spark that ignites the air-fuel mixture in the cylinder. A faulty ignition system will prevent the engine from starting or running properly.

Spark Plug Snafus

The spark plug is a critical component of the ignition system. A fouled, cracked, or improperly gapped spark plug can cause starting problems, misfires, and poor performance.

• Symptoms: Hard starting, misfires, rough idling, lack of power.
• Troubleshooting:
  • Visual Inspection: Remove the spark plug and inspect it. Look for cracks, carbon buildup, or oil fouling.
  • Cleaning: Clean the spark plug with a wire brush or spark plug cleaner.
  • Gapping: Check the spark plug gap with a feeler gauge and adjust it to the manufacturer’s specifications (typically 0.5mm or 0.020 inches for the MS 291).
  • Testing: Use a spark plug tester to check if the spark plug is producing a strong spark.
  • Replacement: Replace the spark plug if it’s damaged or fouled beyond cleaning. I always keep a spare spark plug in my toolkit. It’s a cheap and easy fix that can save you a lot of headaches in the field.
• Cost Considerations:
  • Spark plug: \$5 – \$10
  • Spark plug cleaner: \$5 – \$10
  • Spark plug tester: \$10 – \$20

Ignition Coil Calamities

The ignition coil generates the high voltage needed to create the spark. A faulty ignition coil can prevent the engine from starting.

• Symptoms: No spark, hard starting, engine dies suddenly.
• Troubleshooting:
  • Spark Test: Remove the spark plug and connect it to the spark plug wire. Hold the spark plug against the engine block and pull the starter rope. If there is no spark, the ignition coil may be faulty.
  • Continuity Test: Use a multimeter to check the continuity of the ignition coil.
  • Replacement: If the ignition coil is faulty, it will need to be replaced. Replacing the ignition coil can be a bit more involved than replacing a spark plug, but it’s still a manageable DIY project for most people.
• Cost Considerations:
  • Ignition coil: \$30 – \$60
  • Professional ignition coil replacement: \$80 – \$150

Kill Switch Kerfuffles

The kill switch is a simple but important part of the ignition system. A faulty kill switch can prevent the engine from starting or cause it to die unexpectedly.

• Symptoms: Engine won’t start, engine dies suddenly.
• Troubleshooting:
  • Continuity Test: Use a multimeter to check the continuity of the kill switch.
  • Visual Inspection: Check the kill switch wiring for damage.
  • Replacement: Replace the kill switch if it’s faulty.
• Cost Considerations:
  • Kill switch: \$5 – \$15

Data Points & Statistics:

• Ignition system problems account for approximately 25% of chainsaw repairs.
• The average cost of replacing an ignition coil is between \$80 and \$150.

3. Compression Concerns: Sealing the Power

Compression is the measure of how tightly the air-fuel mixture is compressed in the cylinder. Low compression can cause hard starting, lack of power, and poor performance.

Piston and Cylinder Perils

The piston and cylinder are the heart of the engine. Damage to the piston or cylinder walls can cause low compression.

• Symptoms: Hard starting, lack of power, engine won’t start.
• Troubleshooting:
  • Compression Test: Use a compression tester to measure the compression in the cylinder. A healthy MS 291 should have a compression reading of around 150-170 PSI.
  • Visual Inspection: Remove the muffler and spark plug and inspect the piston and cylinder walls for scoring or damage.
• Cost Considerations:
  • Compression tester: \$20 – \$50
  • Piston and cylinder kit: \$100 – \$300
  • Professional engine rebuild: \$300 – \$600

Ring Realities

The piston rings seal the gap between the piston and the cylinder walls. Worn or broken piston rings can cause low compression.

• Symptoms: Hard starting, lack of power, excessive smoke from the exhaust.
• Troubleshooting:
  • Compression Test: As above.
  • Leak Down Test: A leak down test can help pinpoint the source of compression loss. This involves pressurizing the cylinder with compressed air and listening for leaks.
• Cost Considerations:
  • Piston rings: \$20 – \$50
  • Professional piston ring replacement: \$200 – \$400

Gasket Gaffes

The cylinder gasket seals the cylinder to the engine block. A leaking cylinder gasket can cause low compression.

• Symptoms: Hard starting, lack of power, air leaks around the cylinder.
• Troubleshooting:
  • Visual Inspection: Check the cylinder gasket for leaks.
  • Leak Down Test: As above.
• Cost Considerations:
  • Cylinder gasket: \$5 – \$15
  • Professional cylinder gasket replacement: \$100 – \$200

Data Points & Statistics:

• Compression problems account for approximately 15% of chainsaw repairs.
• The average cost of a chainsaw engine rebuild is between \$300 and \$600.

4. Exhaust System Examinations: Breathing Freely

The exhaust system removes exhaust gases from the engine. A clogged exhaust system can restrict airflow and cause the engine to overheat and lose power.

Muffler Mayhem

The muffler is the main component of the exhaust system. A clogged muffler can restrict airflow and cause the engine to overheat and lose power.

• Symptoms: Lack of power, overheating, black smoke from the exhaust.
• Troubleshooting:
  • Visual Inspection: Remove the muffler and inspect it for carbon buildup.
  • Cleaning: Clean the muffler with a wire brush or carburetor cleaner. I once had a muffler so clogged with carbon that the saw barely ran. After a thorough cleaning, it was like having a new saw again!
• Cost Considerations:
  • Muffler cleaner: \$5 – \$10
  • Muffler replacement: \$50 – \$100

Spark Arrestor Screen Scenarios

The spark arrestor screen prevents sparks from exiting the exhaust system. A clogged spark arrestor screen can restrict airflow and cause the engine to overheat and lose power.

• Symptoms: Lack of power, overheating, engine runs poorly at high RPMs.
• Troubleshooting:
  • Visual Inspection: Remove the spark arrestor screen and inspect it for carbon buildup.
  • Cleaning: Clean the spark arrestor screen with a wire brush or carburetor cleaner. I recommend cleaning the spark arrestor screen every 25 hours of use.
• Cost Considerations:
  • Spark arrestor screen cleaner: \$5 – \$10
  • Spark arrestor screen replacement: \$5 – \$15

Data Points & Statistics:

• Exhaust system problems account for approximately 10% of chainsaw repairs.
• The average cost of replacing a chainsaw muffler is between \$50 and \$100.

5. Cooling System Considerations: Keeping it Cool

The cooling system prevents the engine from overheating. An overheating engine can cause serious damage.

Cooling Fin Fiascos

The cooling fins on the cylinder head dissipate heat. Dirty or damaged cooling fins can reduce the engine’s ability to cool itself.

• Symptoms: Overheating, lack of power, engine damage.
• Troubleshooting:
  • Visual Inspection: Inspect the cooling fins for dirt and debris.
  • Cleaning: Clean the cooling fins with compressed air or a brush. I make it a habit to clean the cooling fins after every use, especially when cutting in dusty conditions.
• Cost Considerations:
  • Compressed air: \$5 – \$10 (if using canned air)

Airflow Obstructions

Anything that blocks airflow around the engine can cause it to overheat.

• Symptoms: Overheating, lack of power, engine damage.
• Troubleshooting:
  • Visual Inspection: Check for obstructions around the engine, such as leaves, twigs, or sawdust.
  • Cleaning: Remove any obstructions.
• Cost Considerations:
  • Typically, no cost involved, just a bit of your time!

Data Points & Statistics:

• Overheating is a major cause of engine damage in chainsaws.
• Regular cleaning of the cooling fins can significantly extend the life of your chainsaw engine.

The Nitty-Gritty: Cost Breakdown & Budgeting

Let’s get down to brass tacks. Owning and maintaining a chainsaw involves a range of costs, from the initial purchase price to ongoing maintenance and repairs. Here’s a breakdown of the costs involved:

1. Initial Investment:

• Chainsaw Purchase: The Stihl MS 291 typically costs between \$400 and \$600, depending on the retailer and any included accessories. I remember when I bought my first MS 291. It was a significant investment, but I knew it would pay for itself in the long run.
• Safety Gear: Safety gear is essential for operating a chainsaw. This includes a helmet with face shield, ear protection, chainsaw chaps, and gloves. Expect to spend between \$100 and \$200 on quality safety gear.
• Basic Tools: You’ll need some basic tools for chainsaw maintenance, such as a scrench (a combination screwdriver and wrench), a file for sharpening the chain, and a feeler gauge for gapping the spark plug. These tools will cost around \$20 – \$50.

2. Ongoing Maintenance:

• Fuel and Oil: Chainsaws require a mixture of gasoline and two-stroke oil. The cost of fuel and oil will vary depending on the price of gasoline and the amount of wood you cut. Expect to spend around \$10 – \$20 per month on fuel and oil if you use your chainsaw regularly.
• Chain Sharpening: A sharp chain is essential for efficient and safe cutting. You can sharpen the chain yourself with a file, or you can take it to a professional. Professional chain sharpening typically costs between \$10 and \$20 per chain. I prefer to sharpen my own chains. It’s a skill that every chainsaw owner should learn.
• Air Filter Replacement: Air filters should be replaced regularly, typically every 25 hours of use. Air filters cost between \$5 and \$10.
• Spark Plug Replacement: Spark plugs should be replaced annually or every 100 hours of use. Spark plugs cost between \$5 and \$10.
• Chain Replacement: Chains eventually wear out and need to be replaced. A new chain for the MS 291 will cost between \$20 and \$40.
• Bar Oil: Bar oil lubricates the chain and bar, reducing friction and wear. Expect to spend around \$10 – \$20 per month on bar oil if you use your chainsaw regularly.

3. Repairs:

• Minor Repairs: Minor repairs, such as replacing a fuel line or cleaning the carburetor, can typically be done yourself. The cost of parts for minor repairs is usually less than \$50.
• Major Repairs: Major repairs, such as rebuilding the engine, can be expensive. Expect to spend between \$300 and \$600 for a professional engine rebuild.

Data Points & Statistics: Wood and Firewood Costs

To put these chainsaw costs into perspective, let’s look at some data on wood and firewood prices:

• Timber Prices: Timber prices vary widely depending on the species, quality, and location. According to the US Forest Service, the average stumpage price (the price paid for standing timber) for sawtimber in the US in 2023 was around \$300 per thousand board feet. However, prices can range from less than \$100 per thousand board feet for low-quality timber to over \$1000 per thousand board feet for high-quality hardwoods.
• Firewood Prices: Firewood prices also vary depending on the species, location, and seller. According to the Hearth, Patio & Barbecue Association, the average price of a cord of firewood in the US in 2023 was around \$250. However, prices can range from less than \$150 per cord in rural areas to over \$400 per cord in urban areas.
• Global Timber Market: The global timber market is influenced by factors such as demand from the construction industry, government regulations, and environmental concerns. Prices for softwood lumber have been particularly volatile in recent years due to supply chain disruptions and increased demand for homebuilding materials. I’ve seen firsthand how fluctuating lumber prices can impact the profitability of small-scale logging operations.

Budgeting Tips:

• Track Your Expenses: Keep track of all your chainsaw-related expenses, including fuel, oil, parts, and repairs. This will help you identify areas where you can save money.
• Perform Regular Maintenance: Regular maintenance can prevent costly repairs down the road. Follow the manufacturer’s recommendations for maintenance intervals.
• Shop Around for Parts: Prices for chainsaw parts can vary widely between retailers. Shop around to find the best deals.
• Learn to Do Your Own Repairs: Learning to do your own repairs can save you a lot of money on labor costs. There are many online resources and tutorials that can help you learn basic chainsaw repair skills.
• Consider Renting: If you only need a chainsaw for occasional use, consider renting one instead of buying one. Rental rates for chainsaws typically range from \$30 to \$50 per day. I used to rent a chainsaw before I bought my own. It was a good way to get started without making a big investment.
• Buy in Bulk: Purchase fuel, oil, and other supplies in bulk to save money.

Story Time: My Chainsaw Mishaps and Lessons Learned

Over the years, I’ve had my fair share of chainsaw mishaps. One time, I was cutting firewood in the dead of winter when my chainsaw suddenly stopped working. It turned out that the fuel line had frozen solid. I had to thaw it out with a lighter (carefully!) before I could get the saw running again. Another time, I was felling a large tree when the chain broke and whipped back at me. Fortunately, I was wearing safety gear, and I wasn’t injured. These experiences have taught me the importance of proper chainsaw maintenance and safety.

Actionable Takeaways

1. Fuel is King: Always use fresh, high-quality fuel with the correct oil mix ratio.
2. Spark it Right: Keep your spark plug clean and properly gapped.
3. Compression is Key: Monitor your engine’s compression and address any issues promptly.
4. Exhaust Matters: Keep your muffler and spark arrestor screen clean.
5. Stay Cool: Ensure proper airflow around the engine to prevent overheating.
6. Safety First: Always wear appropriate safety gear when operating a chainsaw.
7. Maintenance is Money: Regular maintenance can prevent costly repairs.

Next Steps

1. Inspect Your Chainsaw: Take some time to inspect your Stihl MS 291 for any signs of wear or damage.
2. Perform Routine Maintenance: Follow the manufacturer’s recommendations for routine maintenance.
3. Troubleshoot Any Issues: If you’re experiencing any problems with your chainsaw, use the troubleshooting tips in this article to diagnose the issue.
4. Seek Professional Help: If you’re not comfortable performing repairs yourself, take your chainsaw to a qualified repair technician.
5. Stay Safe: Always prioritize safety when operating a chainsaw.

By following these tips, you can keep your Stihl MS 291 running smoothly and efficiently for years to come. Happy cutting! I hope this helps you keep your Stihl MS 291 in top-notch condition. Remember, a well-maintained chainsaw is a safe and productive chainsaw. Now, get out there and make some sawdust!

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