"Ahh... there is nothing like the fresh smell of diesel fuel in the morning...."
| There are a lot of things to consider when buying and/or operating a diesel powered boat. Often overlooked as a power source, when
comparing initial cost to use (compared to gas power plants) by recreational boaters,
commercial power plant of choice is almost always diesel. Recreational
weekend warriors who have diesels usually find that the engine will
rust to death long before they wear it out. So they are not for
With the new offerings of both diesel inboard and diesel sterndrive by several of the top marine engine suppliers, we recommend a closer look at these choices when it's time to re-power your boat or yacht.
A bit about diesel fuel
Large fuel droplets and high "asphalting" concentrations of diesel fuel require more time, more energy and higher temperatures to combust than is available in diesel engines during the combustion cycle. Age of the fuel as well as any device in the fuel system exposing the fuel to stress (heat and pressure) such as injector pumps, fuel heaters, or fuel centrifuges will increase the formation of asphaltenes. If you have diesel fuel that has turned dark, or almost black, in comparison to clear, bright fuel, then it is time to call your local fuel polishing company. This degraded, dark fuel negatively impacts combustion and performance of the engine and can prevent the engine from starting in the first place.
Diesel Dos and Don'ts
Ether and Diesels...
We received an email question concerning the use of ether to start a sluggish diesel. It is very dangerous to implement this procedure. Serious damage can and will occur, if implemented incorrectly. However, in an emergency there are other concerns that might tempt you to try desperate acts to try to get your diesel started and out of danger.
Notice: Electronically controlled diesel engines have special sensors that can/will be damaged and/or thrown out of calibration if subjected to unusual starting procedures, other than those listed in the owners manual.
So, having said that, we'll tempt fate and give you the secret that could keep you off the rocks some day.
First, if your engine has a manual fuel primer lever, pump the lever until it gets firm. Make sure that the transmission is in neutral and that the engine "cranks freely" and is not hydro-locked. (see salvaging a drowned motor)
Then, remove any panel that would be necessary to ventilate the engine room. Turn on any blowers and/or ventilation equipment that would aid in keeping the engine room well ventilated.
If the engine has a cylinder compression relief valve, (usually a lever
located next to the valve cover) open the valve, and have someone crank the engine. When
the engine achieves maximum cranking speed, rapidly close the pressure relief valve and
often this will start the engine. A low battery and/or cold conditions may
attempts at this procedure.
Engines that are not equipped with a cylinder compression pressure relief valve can be a little trickier.
First, follow the safety
above. Then find the air intake, for the engine, and block the air from entering the
intake manifold. [You will have to remove the air cleaner/silencer, in most
cases.] Use your hand, large rubber ball, and/or other item that would
be sucked into the engine when cranking. Have someone crank the engine and after several
revolutions you will note that the rpm's will increase substantially. Remove the air
intake restriction, quickly, and the engine will receive a burst of air that should force
At this point, if you haven't hurt yourself and/or bent a rod on the engine, then the motor should be running. If not, you have a major mechanical problem that needs to be corrected. Toss out an anchor or start paddling.
Start over and go look at some of our tips.
Note: Never try these procedures unless you are completely familiar with all safety and warnings published on this site and in your service manual.
Good luck and be careful...
And for those history buffs out there, they have an interesting time machine page that goes back to the very beginning.
Web Note: The "open in new window" feature, when you click on a hyperlink, is used extensively throughout the new Volvo web site.
Note: The links above, open in a new window.
Engine database and publication search. [Free owners manuals]
Pleasure boat engines [open in new window/tab]
As mentioned earlier, diesel packages for the marine industry have become more available and worth your consideration. "Yanmar" engine company teamed up with Mercruiser, a while back, to offer a diesel sterndrive package that was to become the market leader in it's class. However, it may have been one of the best kept secrets at the same time.
Yanmar's small one and two cylinder diesel engines are popular
with many sailboat builders., though. This is a bulk of what's in the
field in the US.
Maintenance videos for the Yanmar YM, LP and BY engines
Links below allow you to view and/or download the Yanmar Marine maintenance instruction video.
Special Note: The Yanmar video information concerning fuel filter change unfortunately omits that you need to bleed the fuel system after changing the filter. Fuel system bleeding procedure is slightly different for each model they sell so, consult your owners manual.
" Cummins Marine" For marine information including spec sheets, warranty information, service locator, technical application files, etc., Please note that you are not actually at cummins.com by accessing this link but rather entering a Cummins-approved web site.
There is also a joint web site between Mercruiser and Cummins where they have posted specs for their new joint venture.
An interesting new joint venture, utilizing small diesel engines from Volkswagen, has yet to create much buzz. But, the rumor is that Mercruiser just might eventually focus heavily on Cummins/Volkswagen diesel power over gas due to the "catalytic converter" issues associated with gas marine engines. Stay tuned....
Note: The links above, open in a new window.
Have you seen our reference library?