How well do you know your diesel engine?

Do you know what the different arrows are pointing at in the pictures? Have you ever air-locked your engine? Are you nervous about changing the fuel filter on your engine for the first time? Can you change your own oil and filters? Do you want to know how to test your alternator? Or, how to test your start battery? Do you know how to start the engine with an emergency start switch? Have you inspected your cooling system? How about the transmission cooler?

Quick Tips:

1. Install a vacuum gauge in your fuel system after the primary fuel filter to tell you if the system has a blockage or if the primary filter is dirty from bad fuel or a problem in the tank.
2. Overheating can kill a diesel engine. Make sure your cooling system is maintained including flushing the heat exchanger every 3-4 years.
3. There is no warning for salt water incursion in your transmission cooling system. Inspect it annually and replace it every 3-4 years.
4. Impellers should be inspected annually and replaced every 1-2 years depending on use.
5. Consider replacing hoses and belts every 5 years.

Having your diesel engine fail while underway can ruin your day. Worse, it could put you and your crew in danger. Marine diesel engines are incredibly reliable. They seem to just need air, fuel and water. Add electrical power for starting and you have covered the range of needs for a diesel engine. In my experience, however, most engine problems are due to fuel or cooling issues.

Here are two quick tips for maintaining your diesel engine:

1) Make sure the engine is getting a good supply of clean fuel and 2) keep the engine running at its proper temperature – typically from 185 degrees to 205 degrees. You can kill an engine far before it is worn out by lack of cooling system maintenance. How do you know you have problems? Good indicators are the engine losing RPMs or quitting in a seaway, or hearing a blaring high temp alarm from the engine’s cooling system.

What can you do to prevent these issues?

First, make sure you have an early warning indicator for your fuel system, and check on it. How? Every proper cruising vessel has a vacuum gauge installed in the fuel system, after the primary fuel filter system but before the engine. If your fuel filters are starting to get fouled or plugged, the engine must pull harder than normal and this will result in negative pressure after the primary fuel filter. Eventually this negative pressure will become excessive and overcome the engine, resulting in loss of power. The early warning system is a proper vacuum gauge that is installed after the primary filter and before the secondary fuel filter on the engine. The choice of manufacturer isn’t as important as having a “Tell-Tale” – a red needle that records the highest value while running. Make checking this gauge part of the daily checklist when in the engine room! Vacuum gauges usually are color coordinated with green being good, yellow indicating it is time for a filter change, and red indicating a seriously plugged filter and an engine about to quit. A vacuum gauge can pay for itself, too, since it allows you to replace the fuel filter based on condition rather than time.

Next, maintain your cooling system. Replace the coolant each year. Inspect the heat exchanger at least every other year. When you see a scale buildup, send it to a radiator repair shop for cleaning and flushing. The cost is typically reasonable. On most engines, removing a heat exchanger is quick and requires minimal mechanical ability. Inspect your water pump and replace the impeller. Many replace their impeller every year, however, depending on use you might replace it every other year. Inspect all belts and hoses for wear and consider replacing hoses every five years.

Want to learn more? We have classes on Maintaining Diesel Engines at our Cruisers College, each year at Seattle Boat Show University, and other locations, check our website for a schedule or sign up for our newsletter. The goal of our courses are to help you become proficient with the care and maintenance of your diesel engine through a combination of classroom lectures and sessions with real engines you can walk around, tinker with, observe, and start. By the end of the course you will be comfortable with a diesel engine. You will even know how to bleed the fuel system for an engine.