Piston Rings and How They Work

April 2, 2019MechVibesblog

Encountering challenge on piston rings and how they work? Piston rings are design purposely to prevent gas leakage through the clearance which must be left between cylinder and piston to enable free movement.

They are to improve heat transfer from the piston to the cylinder wall, to provide proper lubrication and to control oil consumption. These are semi-enclosed circular rings made from cast iron.

Cast iron is easily coat with other materials to further improve it quality.

Therefore, when fixing piston rings, is advisable to check for its side clearance and gap. Feeler gauge is used to measure ring gap ends.

They are commonly use on small engines and includes compression ring, oil ring and wiper ring.


Diagnosing Black Exhaust Smoke

Compression Ring

This is located in the ring groove closest to the piston head. Its main function is to prevent gas leakage and transfer heat from the piston to the cylinder walls. Further, combustion gas pressure forces the piston ring against the cylinder wall to form a seal.

Oil Ring

Oil rings are located in the ring groove below the compression ring. This help wipe away excess oil from the cylinder wall during the piston movement.

Besides, excess oil are allowed to flow back to the reservoir through holes and slut which are cut into the radial center of the ring.

Wiper Ring

Its also known as backup compression rings or Napier rings. Napier rings are located in the ring groove between the compression ring and oil ring.

Besides, it main function is to wipe the chamber clean and of excess oil. They are made of tapered face which blocks mixtures that pass by when piston move towards the crankshaft.

Symptoms of Bad Piston Rings

  • High consumption of oil.
  • Loss of power.
  • Poor vehicle performance.
  • Excess exhaust smoke.


We hope this article helped you understand piston rings and how they work find. You may also want to check our handpicked of Top 10 Essential Tools to Keep in Your Vehicle and How Car Engine Works to understand basic engine principles.

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