How to Test Piston Rings

  • 2-4 hours
  • Beginner
  • 0-25
What You'll Need
Compression Tester with Adapter
Auto Repair Manual

A piston ring is an open-ended ring that is aimed to make the cylinder that contains the piston gas-tight. It fits on the exterior of the piston and tries to seal the combustion chamber, regulate engine oil consumption and support heat transfer. If you feel there is something wrong with your car, you must test each part individually. The piston ring can be checked without disassembling the engine. The piston ring can be tested by following the step-by-step instructions discussed below.

Step 1 – Removing the Fuse: The fuel pump is controlled by a fuse. This fuse must be removed to bring the car in a safe mode.

Step 2 – Removing Spark Plugs: Each cylinder has a spark plug that must be removed. This can be done by rotating the plug counter-clockwise with the right socket.

Step 3 – Disable Ignition System: The ignition system must be disabled so that any combustion in the cylinder is avoided. To do so, consult the auto repair manual.

Step 4 - Throttle: The throttle must be put in an open position. The location of the throttle can be known from the repair manual.

Step 5 – Attaching Compression Gauge: The compression gauge needs to be fitted on to the spark plug hole in the engine. Spin engine with starter and check the needle on the compression gauge. The needle must move at least four times. This must be done for each cylinder individually.

Step 6 – Checking: If the compression gauge is less than 100 pounds of pressure, you may have a bad piston ring. To re-confirm, squirt some 10w30 motor oil on the piston. If the compression improves, it means the piston rings need to be replaced.