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Diesel Deep Dive by Meredith Anderson
IS YOUR ENGINE SENDING
SMOKE
SIGNALS? In the 1890s, Rudolf Diesel created the first compression ignition oil-burning engine, and it was was large, heavy, smoky, and slow turning. While the general engineering behind today’s diesels hasn’t changed from the initial invention, a lot has evolved in terms of efficiency and performance. Today's diesels are significantly cleaner burning and are not the chugging smoke-machines we commonly think of when we think diesel. The majority of diesel engines I see in recreational and commercial applications today range in age from approximately 60 years old to brand new. I have seen 60-yearold engines that are meticulously maintained showing almost no smoke, or none at all. Engines made within the last 20 to 30 years came off their manufacturing line running clean with little-to-no smoke.
A clean and unclogged exhaust elbow is part of a smoke-free engine. 48º NORTH
As boaters and boat owners, consider smoke the result of something going on within the engine that needs to be addressed. It can be relatively benign, or extremely serious. Understanding what your exhaust is trying to tell you can help you stop a problem before it causes real damage, or at least it can help prevent problems in the future. I once was called to work on a boat where both diesel engines had significant smoke coming out of their exhaust pipes — nothing crazy, but definitely noticeable. The vessel had a recent mechanical survey done and written in the survey were the words: “Smoke is normal for these engines.” I was appalled that a diesel mechanic would say that. It turns out the engines had several problems, but the biggest was that both had signs of multiple components beginning to fail. The mechanic had failed to see or honor this — perhaps this person thought all diesels smoke. In this oversight, the mechanic failed the customer, who purchased the vessel believing the engines were fine, when in fact they were not. It was a frustrating realization for the customer to discover how much work would be required. I left feeling terrible that such an obvious issue had gone overlooked. Smoke from an engine tells quite a story, providing huge diagnostic clues to us mechanics as we try to figure out what is going on. Engines are very much like humans — they can have health issues just like we can. Medical professionals look, listen, and feel for clues to understand what is going on with their patient. It is no different with an engine. When performing an inspection on an engine, I look, listen, and feel for any abnormalities when the engine is running or not. I always get off the boat and watch the exhaust when
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JUNE 2021
