diesel additives
- Thread starter redhead78
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A number of diesel mechanics in my area recommend the use of "Pri-D " (available on this site and WM, Defender, etc.) and I have used it for many years. While I don't know if it makes any difference, I do know that I have not had any fuel related engine problems in that time. I use about 1/4 ounce per 2 gals of fuel. I also use a commercial cetane booster as my Yanmar 2GM20F requires a cetane rating of 45 and the fuel I buy at truck stops is rated at 40. Check your engine manual for what you should be using. The higher cetane rating eases starting and reduces smoke in the exhaust.
Red: One thing to keep in mind is that there are two different kinds of additives for two different purposes. The one discussed so far is for conditioning the fuel and boosting the cetane rating. The other kind is a biocide to keep the fuel eating bacteria from multiplying. These bacteria grow in the water/fuel interface layer and can very quickly clog your fuel filters. It is actually pretty common, especially in the summer and in warmer climates. You can buy the biocide at WM, Defender, etc. Also, note that you can use both of these kinds of additives simultaneously.
I had a huge mess in my tank as a result of using a biocide additive. Immediately following the addition of the biocide my fuel filter began to clog and finally the fuel pickup actually plugged up!! I was told afterward that I should NEVER add biocide to a tank that has been in use for several years. Mine had gone at least 6 years without additives. The flora and fauna that naturally occur in the tank will be killed off instantly and sink to the bottom causing a sludge that will be BIG PHUN to clean! If You clean the tank first or have a new tank, then by all means use appropriate additives to control the critters.
cat38skip is correct. You have to be very careful with the use of additives. I had a mess from bad fuel picked up in GA (Kilkenny Creek) that caused problems for a couple of years. I killed all the critters and they in turn clogged the pickup tube, which I did not know had a mesh filter screen in it - (some boats have the screen and others don't - it pays to know what you have). After considerable frustration, aborted trips, hair raising entrances into Inlets with motors quitting, I finally took out the pick up tube and removed the screen. Also cleaned the tank, figuring that it was a heck of a lot easier and cheaper to replace my primary filter. I have not had a problem since.
- Dec 30, 2009
- 680
How would I go about cutting out an inspection and cleanout hole in the top of my tank, while in place. What woulld I use that would not cause sparks/fire. I believe it is SS. I will look at it again this weekend, I think removing it may be quite a job.
Redhead,
Direct from my Hunter dealer in Deltaville, VA. Don't use a biocide. Rather keep your diesel tank clean (buy clean fuel and use a fuel funnel filter if the source is suspect, etc.) Periodically vacuum the tank bottom every few years (easily done by removing the fill hose on top of the tank. Try using your oil changer and remove a gallon or so of diesel. You'll see if there's crud inside the tank). Commercial diesel is approx 40 cetane - Yanmar's like 45 centane so buy yourself some centane booster and add it to your tank per the directions. Last, add a water absorbant additive to the tank. Without water in your tank you won't have the algea problem since they need water to grow. Water gets into your tank through condensation, rain and other leak areas. Without the water, no algea and no need to worry about your fuel. Good maintenance is critical however.
Direct from my Hunter dealer in Deltaville, VA. Don't use a biocide. Rather keep your diesel tank clean (buy clean fuel and use a fuel funnel filter if the source is suspect, etc.) Periodically vacuum the tank bottom every few years (easily done by removing the fill hose on top of the tank. Try using your oil changer and remove a gallon or so of diesel. You'll see if there's crud inside the tank). Commercial diesel is approx 40 cetane - Yanmar's like 45 centane so buy yourself some centane booster and add it to your tank per the directions. Last, add a water absorbant additive to the tank. Without water in your tank you won't have the algea problem since they need water to grow. Water gets into your tank through condensation, rain and other leak areas. Without the water, no algea and no need to worry about your fuel. Good maintenance is critical however.
- Dec 30, 2009
- 680
So water absorbent additives should do it, sounds reasonable. What cetane #,s would I need for a new 35 hP beta Kubota. I usually try to buy diesel from a dealer who moves a lot of gas. Right now I am buying on the street, any particular brands better than others in your experience. With my 2 cyl renault it did not seem to make a difference, rather I probably just could not tell. Red
Inspection Port
Hey Red,
Check out www.seabuilt.com. Dan Johnson turned me on to them. They make inspection ports specifically for boat fuel tanks. I just installed an 8" port today on a poly tank to replace a Beckson plate that was leaking. I believe they also make ports for metal tanks. You don't need to remove the tank as long as you have access to the top of it but you must remove all the fuel prior to installation. You simply remove the fuel through the fill hole, cut a hole in the top of the tank, clean out the tank by hand, install the port (very easy to do), and replace the fuel.
Two other idea's are to remove the screen from the bottom of the pick-up tube so if there is any gunk it won't clog at the pickup point but will instead be caught at the primary filter. The other idea is to cut the pickup tube so that it is 1 1/2 - 2" off the bottom of the tank. Since a lot of the crap will sit on the bottom not having the tube all the way down there may help to avoid picking it up in the first place. Then with your new port installed you can easily clean out your tank every two or theee years.
Good luck,
Joe Mullee
Hey Red,
Check out www.seabuilt.com. Dan Johnson turned me on to them. They make inspection ports specifically for boat fuel tanks. I just installed an 8" port today on a poly tank to replace a Beckson plate that was leaking. I believe they also make ports for metal tanks. You don't need to remove the tank as long as you have access to the top of it but you must remove all the fuel prior to installation. You simply remove the fuel through the fill hole, cut a hole in the top of the tank, clean out the tank by hand, install the port (very easy to do), and replace the fuel.
Two other idea's are to remove the screen from the bottom of the pick-up tube so if there is any gunk it won't clog at the pickup point but will instead be caught at the primary filter. The other idea is to cut the pickup tube so that it is 1 1/2 - 2" off the bottom of the tank. Since a lot of the crap will sit on the bottom not having the tube all the way down there may help to avoid picking it up in the first place. Then with your new port installed you can easily clean out your tank every two or theee years.
Good luck,
Joe Mullee
I would not cut the pickup tube (apologies to Joe). That solution does not remove the gunk from the tank and when the boat is getting knocked about in poor sea state conditions the pickup tube will still clogg. On the other hand removing the screen allows the junk to pass into the primary filter which can be easily replaced, even in poor sea conditions, depending upon where it is located. I made 2 dramatic changes to my fuel system's filtration system. 1) relocated the filter (upgraded to a turbo) to the aft cockpit locker where it can be gotten to quickly while underway, single handing; 2) added a 2nd primary filter (spin on) mounted next to the turbo and controlled via a three way valve. The only thing to remember with this set up is to occasionally change to the other filter to replace the fuel in those lines with fresh. This solution, and the removal of the pick up tube screen has apparently solved the problem I was having for several years. (See previous post). As someone else suggested it is a good idea to OCCASIONALLY (!) use a water absorber and a (again occasionally) biocide. A cetane booster is recommended.
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