1. Worn Piston Rings: Piston rings seal the combustion chamber, maintaining compression. Worn or damaged rings allow gases to escape, resulting in low or no compression.
2. Cylinder Bore Damage: Scratches or defects in the cylinder bores caused by excessive wear or overheating can prevent the piston rings from forming a proper seal, leading to compression loss.
3. Leaking Valves: Worn valve seals or damaged valves can result in compression leakage past the valves instead of building up in the cylinder.
4. Head Gasket Failure: A blown head gasket between the cylinder head and the engine block can create a path for compressed gases to escape, causing low compression.
5. Failed Compression Release Mechanism: In certain engines, a compression release mechanism is used to aid in starting. If this mechanism malfunctions or fails, it can interfere with proper compression building.
6. Timing Issues: Incorrect timing, such as misaligned timing marks or worn timing components (timing belt or chain), can affect valve and piston operation, leading to compression problems.
7. Bent or Broken Connecting Rod: A bent or broken connecting rod can disrupt the movement of the piston within the cylinder and affect compression.
8. Camshaft Issues: If the camshaft timing or lift is compromised due to worn components or mechanical problems, it can impact valve movement and affect compression.
A professional mechanic using compression testing equipment can accurately diagnose the source of the compression loss and provide the necessary repairs.
