1. Piston Rings:
- Worn or damaged piston rings fail to seal properly, causing excessive leakage of the combustion gases past the piston.
2. Cylinder Bore:
- Wear or damage to the cylinder bore, such as scoring or scuffing, can also lead to poor sealing and low compression.
3. Head Gasket:
- A blown or damaged head gasket can allow combustion gases to escape between the cylinder head and engine block, resulting in low compression.
4. Valves:
- Improper seating or damage to valves, such as burnt or bent valves, can cause insufficient sealing, leading to low compression.
5. Piston Seal:
- If the piston's top ring land or ring grooves are worn or damaged, it can result in poor piston-to-cylinder sealing, causing low compression.
6. Camshaft Timing:
- Incorrect valve timing, especially if the valves do not open or close at the right moments during the engine cycle, can lead to low compression.
7. Carbon Buildup:
- Excessive carbon deposits on the piston, cylinder head, and valves can interfere with proper sealing, causing low compression.
8. Damaged or Worn Piston:
- A cracked, scuffed, or damaged piston can also contribute to low compression.
9. Leaking Intake or Exhaust Valves:
- Leaking valves can result in a loss of compression and reduced engine performance.
10. Worn or Damaged Piston Pin:
- Excessive wear or damage to the piston pin or connecting rod bearings can lead to increased clearance and reduced compression.
It's important to note that low compression on a single cylinder can also be caused by a combination of factors, and further diagnosis may be required to identify the exact root cause.
