Engine piston: common defects and their signs

1. Burning-off
   • There is clear knocking sound when the engine is cold which disappears after warm-up.
   • Smoke from the exhaust pipe becomes bluish.
   • Throttle response worsens.
   • The engine loses power.
2. Abrasive wear
   • Motor oil consumption increases.
   • Starter work worsens.
   • Failures in engine work appear.
3. Breakage
   • Noise appears when engine is working.
   • Engine power lowers.
   • Fuel consumption increases.

How to replace an engine piston?

Manufacturers do not specify a certain lifetime limit for the engine connecting rods and pistons. A broken piston is not subject to repair because it is a one-piece element. If defect signs appear the component is to be immediately replaced.

The replacement algorithm depends on component design which can differ for petrol and diesel engines. Cars which work on diesel fuel require a more complicated form of the piston crown. In general, the replacement procedure is rather laborious, time-consuming and includes several steps. In order to gain access to the component one needs to demount the catalytic converter, air conditioner compressor and the oil sump. The second stage includes removal of the battery, intake manifold, pump, alternator, fuel rail, throttle unit, camshafts and cylinder head. The final stage includes demounting and replacement of the defective piston together with sealing piston rings.

Such a work requires professional equipment and special skills, so it should be performed at a service station only.