Introduction
Engine type: 6EY18ALW
Maker: YANMAR
This document briefly introduces two common issues and their solutions for reference by marine engineers.

I. Carbon Deposits, Corrosion, and Lubricating Oil Contamination in Cylinder Heads
1. Fault Description
Three YANMAR AEs on a vessel exhibited poor combustion performance. Under single-engine operation at normal load, exhaust temperature deviations between cylinders exceeded 40°C, with the highest cylinder exhaust temperature reaching 470°C.
Additionally, the lubricating oil in the sump of all three engines was contaminated at an abnormally rapid rate. The oil required replacement within less than 500 hours due to high differential pressure alarms from the self-cleaning filters.

Introduction
Engine type: 5DK-20
Maker: Anqing-Daihatsu
This model lacks an attached F.O supply pump, relying entirely on the fuel supply unit to maintain pressure.
When operating on HFO, the auxiliary engines share a common fuel supply pipeline with the main engine, with a pump discharge pressure of 0.8 MPa.
When operating on MDO, an emergency pump supplies independently, maintaining the same discharge pressure of 0.8 MPa.
A sudden drop in fuel pressure during operation can trigger load surges and blackouts, posing significant operational risks.