Engine
Piston & Rings
Pistons convert combustion pressure into linear motion that the crankshaft turns into rotation.
Free guide
Advertisement
Combustion flow
Interactive — tap a partTap a part to see how it fits in the system.
What it does
- Slides in the cylinder sealing combustion
- Ring pack seals compression and controls oil
- Transfers force to the connecting rod
When it fails
- Blue smoke on acceleration (oil burning)
- Oil consumption
- Loss of compression
- Knocking from inside the engine
How to diagnose
- Compression test and leak-down test
- Check spark plug tips for oil fouling
- Smoke test the PCV system first
Maintenance
- Fix overheating causes to protect pistons
- Do not over-rev a cold engine
- Address detonation immediately
Use the diagnosis order. When a part fails, confirm each hypothesis with measurements before replacing anything — codes and symptoms overlap.