Common Causes of No Compression in a Briggs & Stratton Engine:
1. Worn Valve Seals/Guides: The valve seals prevent oil from entering the combustion chamber, and the guides ensure the valves move smoothly. Over time, they can wear out, leading to:
* Oil Consumption: Noticeable oil burning, smoke from the exhaust.
* Loss of Compression: Oil in the cylinder reduces compression.
2. Worn Piston Rings: Piston rings seal the gap between the piston and the cylinder wall, preventing combustion gases from escaping. If they wear out, you'll experience:
* Loss of Compression: A major indicator of worn rings.
* Blue Smoke: Blue smoke from the exhaust indicates burning oil.
3. Damaged Cylinder Walls: If the cylinder walls are scored or worn, it creates a gap between the piston and the cylinder, leading to loss of compression.
4. Burned Valves: Burnt valves are a result of overheating or excessive wear. This causes a lack of compression and may result in a rattling sound.
5. Valve Timing Issues (Even if you think it's in time): While you've confirmed the timing, double-check it to ensure the valves are opening and closing at the correct times. Even a slight misalignment can affect compression.
6. Damaged Head Gasket: A blown head gasket allows combustion gases to escape into the cooling system, causing:
* Loss of Compression: A major indicator of a blown head gasket.
* White Smoke: White smoke from the exhaust indicates coolant being burned.
Troubleshooting Steps:
1. Check for Leaks: Look for leaks around the valve cover, head gasket, and intake/exhaust manifolds.
2. Compression Test: Use a compression tester to determine the actual compression reading. This is the most reliable way to pinpoint compression issues.
3. Visual Inspection: Remove the spark plug and visually inspect the cylinder for signs of wear, oil, or debris.
4. Valve Inspection: Remove the valve cover and carefully inspect the valves, springs, and guides for wear or damage.
5. Check for Timing: Double-check your timing marks to ensure everything is correctly aligned.
6. Consider Professional Help: If you're unsure about any of the steps above or find significant damage, it's best to seek assistance from a qualified mechanic.
Additional Tips:
* Use a quality compression tester. A cheap tester might give inaccurate readings.
* Ensure the engine is at operating temperature before testing. This provides a more accurate compression reading.
* Don't over-tighten bolts or nuts during inspection or repairs. This can damage engine components.
Remember: Addressing a lack of compression is crucial for keeping your Briggs & Stratton engine running smoothly. Diagnosing the issue early can save you from further engine damage and costly repairs.
