Author: Bullbuster Team
The Non-Mechanic’s Guide To Troubleshooting Your Boat’s Diesel Engine

If you own a fishing boat with a Diesel Engine, chances are you’ve heard the acronym B.O.A.T (break out another thousand). When it comes to getting your engine fixed, you just want to get back on the water so you can spend more time fishing. You’ve got your tackle together your reels spooled with fresh fishing line, you’ve got your rigs pre-made, its time to fish, but your engine is acting up. What do you do?

**** All Advice In This Article Is Solely To Be Used As A Guide To Provide Better Understanding, We Still Recommend Working With A Mechanic ****
How To Save Time & Money When Fixing Your Boats Diesel Engine
Its important to have a good mechanic. Its Important To Have A Good Mechanic, But Its Just As Important To Know A Thing Or Two About Your Engine Even when you do have one, sometimes they are out of reach and you need to get your engine fixed! The last thing that you’re going to want to do is to pay a mechanic an hourly rate to start off in one direction and then find out you have a totally different issue. This HUGE Resource should set you off in the right direction when it comes to trouble shooting your Diesel Engine’s issues.
Below is a video posted by "Capt Steve Russel" about engine room basics. This is a good starting place.
When You Know The Issue, You Can Often Find Parts More Inexpensively Then If You Ask A Mechanic To Source Them For You
If your boat’s diesel engine is more than a few years old, chances are you can find a after market parts for it. There is a lot of hype some Diesel Engine companies that buying original parts is what you need, but you can often find parts from reputable after market distributors with the same or better quality at a fraction of the price.
Below is a list of reputable after market parts suppliers for marine diesel engines.
Parts For Marine Detroit Diesel Engines

Parts For Marine Cummins Diesel Engines

Parts For Marine Caterpillar Diesel Engines

Parts For Marine John Deer Diesel Engines

Parts For Marine Yanmar Diesel Engines

Common Issues With Marine Diesel Engine Issues
Below we list some common Diesel Engine Issues and what might be their cause. Throughout this article you will find links to additional resources that can help you more specifically with your issue.
Things To Check If Your Diesel Engine Will Not Start:
1) Check Your Blower – Your engine needs air to make its internal explosions happen, if something is wrong with your Blower, then your engine is going to have a hard time starting.
What May Be Wrong With It :You may have a worn out our broken blower shaft.
2) Check Your Air Intake – If no air is able to get into your engine, then there is no way your engine is going to start up.
3) Check Your Fuel Pump – If your fuel pump is not working, nothing is going to be pushing the fuel where it needs to go.
4) Checked Your Starter – Your starter may not be engaging the engine when you turn the key. Have someone try to start the engine while you take a look at the starter.
The video below posted by " Mike Lauer" shows a common issue with starters (corrosion). This starter may not be the same one that you have on your engine, but it may be the same issue.
5) Check Your Battery – It is always good to have a volt-meter on board, without power, your starter is not going to work.
6) Check Your Exhaust - If o air is able to come out of your engine there is no way for new air to come in. The flow simply will not work.
Things To Check If You Have Black Smoke Coming Out Of Your Engine
If the video below (posted by Rompcity) looks familiar to you, you may want to check this section out.
1) Check Your Injectors – You may have a faulty injector.
The video below posted by "Toxic Diesel" shows bad injectors on a Cummins 5.9.
2) Fuel Contamination - This is a good time to take a look at your fuel filters to see if they are removing any contaminates from the fuel.
Check out this video posted by "Sea Tech Marine" that explains how fuel contamination can affect your engine:
3) Broken Or Worn Cylinder Parts – Your cylinder head for anything that looks out of the ordinary.
4) Your Engine May Be Overloaded –
5) (If You Have A Turbo) You may have a faulty inter cooler or after cooler.
Ok so we covered the tip of the iceberg about this issue above. By checking into each of the items above you are well on your way. For more info on this common boat diesel engine issue check out the video below posted by "Bell Performance".
White Smoke Coming Out Of The Engine
1) You May Have A Broken Piston Ring
2) Your Ringset May Be Installed Incorrectly –
3) You May Have A Defective Injector –
The video below posted by "Toxic Diesel" shows bad injectors on a Cummins 5.9.
4) You May Want To Get Some New Fuel - White smoke coming out of your engine can be a sign that you have low quality fuel in your engine.
5) You May Need To Run Your Engine More Often - If you aren’t going to be using your boat too often, you may want to stop by it every once in a while just to start it up.
6) Check Your Push Rod - White smoke is sometimes a sign that you have a broken or bent push rod.
7) Your Injectors may need to be adjusted
The video below posted by "Toxic Diesel" shows bad injectors on a Cummins 5.9.
8) Governor calibration may be needed. Below are two videos about it, one gets more technical, one gets more to the point, we included both because everyone has a different style of learning.
This video posted by "addrossi85" shows an old school technical video to calibrate the governor on a Detroit Diesel engine.
This video posted by "avon picture this" is a less technical and more to the point video about how to calibrate your governor.... be careful!
Low Engine Oil Pressure
1) Check your oil pan for water or fuel.
2) Check your oil cooler
3) Your Engine May Be Overloaded
4) Your Crankcase may be overfilled.
Low Engine RPM
You may have an improperly working injector.
The video below posted by "Toxic Diesel" shows bad injectors on a Cummins 5.9.
You may need to improve the calibration on your Governor.
Hi Engine RPM
Governor calibration may be needed. Below are two videos about it, one gets more technical, one gets more to the point, we included both because everyone has a different style of learning.
This video posted by "addrossi85" shows an old school technical video to calibrate the governor on a Detroit Diesel engine.
This video posted by "avon picture this" is a less technical and more to the point video about how to calibrate your governor.... be careful!
Engine Overheating
1) Check Your Freshwater Pump - Water is your engines natural cooling system.
Below are a few videos that can be found both on Youtube and on OffCenterHarbor.com
The video below posted on Youtube by "OffCenterHarbour" covers a Yanmar, but the basic ideas can be applied to any marine diesel engine. This is only one part of a SERIES ON THE COOLING SYSTEM. If you want to know more about it click the video and you will have access to the entire series.
2) Check your raw water pump - Your boats engine is constantly bringing water in from the surrounding waters. This water cools the freshwater in you engine which cools the rest of your engine.
Check out the video below posted by Scott Fratcher which is a good guide to potential problems with your engines cooling systems.
3) Check your thermostat or the thermostat seal – Sometimes its not you engine overheating, it may just be the sensor that takes the temperature.
Grey Smoke Coming Out Of Engine
1) Long Idle Period - If you don’t use your boat for a long period of time, you may want to stop by and start her up every once in a while. No engine likes to be sitting doing nothing for too long.
2) Check your intercooler or aftercooler ( if you have a turbo)
3) Restrictive Air Intake
4) Defective Injector
The video below posted by "Toxic Diesel" shows bad injectors on a Cummins 5.9.
5) Contaminated Fuel
Check out this video posted by "Sea Tech Marine" that explains how fuel contamination can affect your engine:
6) Blower Or Turbo Charger Seals Leaking
Geartrain Making Noises
Check out this video posted by "Daniel Babbet" going over the gear train on a Cummins Engine.
1) Low oil level
2) Engine driven accessories
3) Check your main and rod bearings
**** All Advice In This Article Is Soley To Be Used As A Guide To Provide Better Understanding, We Still Recommend Working With A Mechanic ****
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