- Occurs in medium speed engines.
- Build up of lacquer on liner grooves -Glazing due to which cylinder LO consumption increases.
- If left unnoticed - Scoring \ polishing of liner and operating cost of engine
Because of1. Large variation of load \ frequent \ prolong perios of idle running followed by full load.
2. High mean effective pressure
How?The time for injection , injection and combustion is very small.
Therefore beside complete combustion , thermal cracking of fuel component can be expected .
If these cracked component reach relatively cylinder liner , they will condense , concentrate and start formal sticky resinous lacquer of process of polymerization and evaporation of light ends
- Fuel droplets injected at HP begins to burn rapidly
- Rapid burn leads to incomplete combustion of some layer fuel droplets but intense heating of droplet corresponds
- Thermal cracking of some fuel components occurs within larger drop.
- Some droplets impinging on cylinder liner where thernal cracking reaction c ontinuse to form unsaturated reactive ydrocarbon
- Condensation and polymerisation of unsaturated products of the liner forms resinous organic polymeric deposit.
- Sticky resinous deposit is spread over te liner by piston ring movement.
- Lubricant including metal - containing additives beconmes entrained in the deposit.
- Continual dexposure of the deposit to combustion , evaporation of light ends and rubbing by piston movement forms hardened lacquer deposit.
- Build up of lacquer fills honing grooves and leads to increased rate of oil consumption