Echo CS-590 Wont Start (5 Expert Fixes For Low Compression)

Echo CS-590 Wont Start (5 Expert Fixes for Low Compression)

Many folks believe that if a chainsaw doesn’t start, it’s automatically a fuel issue. While fuel problems are common, low compression is a silent killer of chainsaw performance. I’ve seen countless Echo CS-590s, workhorses in the logging and firewood industry, sidelined by low compression. Don’t assume it’s just bad gas; let’s dive into diagnosing and fixing low compression in your Echo CS-590.

Understanding Compression and Why It Matters

Compression is the measure of how tightly the air/fuel mixture is squeezed inside the cylinder before ignition. A healthy engine needs good compression to create a powerful explosion. Low compression means a weak or nonexistent explosion, leading to a chainsaw that’s hard to start, lacks power, or simply won’t run. Think of it like trying to throw a punch with a limp arm – the power just isn’t there.

Diagnosing Low Compression: The Pull-Start Test

Before tearing into the engine, I always start with a simple pull-start test. Here’s how:

Turn off the chainsaw: Ensure the switch is in the “off” position.
Pull the starter cord slowly: Feel for resistance. A healthy engine will have a noticeable “bounce back” as you pull, indicating good compression.
Listen closely: A healthy engine will have a distinct “whoosh” sound. A weak or nonexistent bounce back, or a hissing sound, suggests low compression.

This test is a quick indicator, but it’s not definitive. A compression tester provides a precise measurement.

Using a Compression Tester: A More Precise Method

A compression tester is the best way to accurately determine your engine’s compression.

Warm-up the engine (if possible): A slightly warm engine provides a more accurate reading. If your chainsaw won’t start, skip this step.
Remove the spark plug: Use the spark plug wrench that came with your CS-590.
Install the compression tester: Screw the tester into the spark plug hole, ensuring a tight seal.
Pull the starter cord repeatedly: Pull the cord firmly and consistently until the needle on the tester stops rising.
Record the reading: Note the highest reading achieved.

What’s a good compression reading for an Echo CS-590? Aim for around 150-170 PSI (pounds per square inch). Anything below 120 PSI indicates a significant compression issue. I’ve seen engines struggle to start below 100 PSI.

5 Expert Fixes for Low Compression on an Echo CS-590

Now that we’ve confirmed low compression, let’s tackle the potential causes and solutions. These are the five most common issues I’ve encountered and the steps to address them.

1. Loose Spark Plug: The Easiest Fix

Sometimes, the simplest solution is the correct one. A loose spark plug can leak compression.

Action: Tighten the spark plug. Use the spark plug wrench and ensure it’s snug but not overtightened. I prefer tightening it to the point where it’s snug, then giving it an additional quarter turn.
Why it works: A properly tightened spark plug creates a tight seal, preventing compression from escaping.
Expected Outcome: If a loose spark plug was the sole problem, your compression reading should improve, and the chainsaw should start more easily.
Next Steps: If the problem persists, move on to the next fix.

2. Carbon Buildup on the Piston and Cylinder Head

Over time, carbon deposits can accumulate on the piston and cylinder head, reducing combustion chamber volume and affecting compression.

Action: Decarbonize the engine. This involves removing the cylinder head and carefully cleaning the piston and cylinder head with a carbon cleaner and a soft brush.
How to do it:
1. Remove the muffler: Disconnect the muffler from the cylinder.
2. Remove the cylinder head: Carefully detach the cylinder head, noting the placement of any gaskets.
3. Clean the piston and cylinder head: Use a carbon cleaner (specifically designed for engines) and a soft brush to gently remove carbon deposits. Avoid scratching the surfaces.
4. Reassemble: Reinstall the cylinder head with a new gasket (if necessary) and reattach the muffler.
Why it works: Removing carbon buildup restores the proper combustion chamber volume, improving compression.
Tool List: Socket set, wrench set, carbon cleaner, soft brush, new cylinder head gasket (if needed).
Personal Experience: I once worked on a CS-590 that had been running on poor-quality fuel for years. The carbon buildup was so severe that it was affecting the valve timing. After a thorough cleaning, the engine ran like new.
Expected Outcome: Improved compression reading and easier starting.
Next Steps: If compression remains low, the issue likely lies with the piston rings or cylinder itself.

3. Worn or Damaged Piston Rings

Piston rings seal the gap between the piston and the cylinder wall, preventing compression from escaping. Worn or damaged rings are a common cause of low compression.

Action: Replace the piston rings. This requires removing the cylinder and piston.
How to do it:
1. Remove the cylinder: Following the steps from decarbonizing, completely remove the cylinder.
2. Remove the piston: Carefully detach the piston from the connecting rod. You’ll likely need to remove a wrist pin.
3. Remove the old rings: Use a piston ring expander tool to carefully remove the old rings.
4. Install the new rings: Install the new rings, ensuring they are properly seated in the piston grooves and that the ring gaps are staggered according to the manufacturer’s instructions.
5. Reassemble: Reinstall the piston and cylinder, using a new base gasket.
Why it works: New piston rings create a tighter seal, restoring compression.
Tool List: Socket set, wrench set, piston ring expander, piston ring compressor, new piston rings, new base gasket.
Important Note: Always use high-quality piston rings designed specifically for the Echo CS-590. Cheap aftermarket rings can cause more problems than they solve.
Case Study: I once worked on a logging operation where several CS-590s were used heavily. We found that replacing the piston rings every 500 hours of use significantly extended the life of the engines and prevented major breakdowns.
Expected Outcome: Significant improvement in compression and engine performance.
Next Steps: If compression is still low after replacing the piston rings, the cylinder itself may be damaged.

4. Scored or Damaged Cylinder Wall

Scratches or gouges on the cylinder wall prevent the piston rings from sealing properly, leading to compression loss.

Action: Inspect the cylinder wall for damage. If the damage is minor, you might be able to hone the cylinder. If the damage is severe, the cylinder will need to be replaced.
How to do it:
1. Inspect the cylinder: Carefully examine the cylinder wall for scratches, gouges, or scoring.
2. Honing (Minor Damage): If the damage is minor, use a cylinder hone to smooth the surface. Follow the hone manufacturer’s instructions carefully.
3. Replacement (Severe Damage): If the damage is severe, replace the entire cylinder.
Why it works: Honing smooths minor imperfections, allowing the piston rings to seal better. Replacing the cylinder eliminates severe damage.
Tool List: Cylinder hone (if honing), new cylinder (if replacing), socket set, wrench set, honing oil (if honing).
Practical Tip: When honing a cylinder, use light pressure and plenty of honing oil. Over-honing can damage the cylinder.
Measurement: After honing, check the cylinder bore diameter to ensure it’s within the manufacturer’s specifications.
Expected Outcome: Improved compression and engine performance.
Next Steps: After addressing the cylinder, recheck compression and ensure the chainsaw starts and runs properly.

5. Leaking Crankshaft Seals

Crankshaft seals prevent air from entering the crankcase, which can affect compression. Leaking seals can cause a loss of vacuum and lean fuel mixture, making the chainsaw difficult to start.

Action: Inspect and replace the crankshaft seals. This requires disassembling the engine.
How to do it:
1. Disassemble the engine: This is a complex process that involves removing the clutch, flywheel, and other components to access the crankshaft.
2. Remove the old seals: Use a seal puller or a small screwdriver to carefully remove the old seals.
3. Install the new seals: Use a seal installer tool to press the new seals into place.
4. Reassemble the engine: Reassemble all the components in the reverse order of disassembly.
Why it works: New crankshaft seals create a tight seal, preventing air leaks and restoring proper crankcase pressure.
Tool List: Socket set, wrench set, seal puller, seal installer, flywheel puller, clutch removal tool, new crankshaft seals.
Safety First: When disassembling the engine, take photos or make notes to ensure you can reassemble it correctly.
Real-World Example: I once encountered a CS-590 that was incredibly difficult to start, even after addressing the piston rings and cylinder. It turned out that the crankshaft seals were cracked and leaking. Replacing them solved the problem.
Expected Outcome: Improved starting and idling, and overall engine performance.
Final Step: After reassembling the engine, check compression and ensure the chainsaw starts and runs properly.

Preventing Low Compression: Maintenance is Key

Preventing low compression is far easier than fixing it. Here are some key maintenance practices I swear by:

Use high-quality fuel and oil: Always use fresh, high-octane fuel and a good-quality two-stroke oil mixed at the correct ratio (typically 50:1). I prefer using ethanol-free fuel whenever possible.
Clean the air filter regularly: A dirty air filter restricts airflow, causing the engine to run rich and increasing carbon buildup. Clean the air filter every few hours of use.
Maintain proper chain tension: A loose chain puts extra strain on the engine.
Sharpen the chain regularly: A dull chain forces you to work the engine harder, leading to increased wear and tear.
Store the chainsaw properly: When storing the chainsaw for extended periods, drain the fuel tank and run the engine until it stalls to prevent fuel from gumming up the carburetor.

The Importance of Safety

Working on a chainsaw can be dangerous. Always wear appropriate safety gear, including gloves, eye protection, and hearing protection. Disconnect the spark plug before working on the engine to prevent accidental starting. If you are not comfortable performing any of these repairs, take the chainsaw to a qualified mechanic.

When to Call a Professional

While many of these repairs can be done at home, there are times when it’s best to call a professional. If you are not comfortable disassembling the engine, or if you suspect that there is damage to the crankshaft or other internal components, it’s best to take the chainsaw to a qualified mechanic.

Conclusion: Reviving Your Echo CS-590

Low compression doesn’t have to be the end of the road for your Echo CS-590. By systematically diagnosing the problem and following these expert fixes, you can often restore your chainsaw to its former glory. Remember to prioritize safety and perform regular maintenance to prevent future issues. With a little effort and the right knowledge, you can keep your CS-590 running strong for years to come. I’ve personally brought dozens of seemingly dead chainsaws back to life, and I’m confident you can too! Now, get out there and get cutting!

Echo CS-590 Wont Start (5 Expert Fixes for Low Compression)