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A few years back I had a diesel-powered boat. The lesson that was learned very quickly was that diesel fuel in a boat has a bacterial growth which ensues from warmth, humidity and lack of use (the engine stops once the filters are clogged: Bad). So boat users use some overpriced diesel conditioner.
Can anyone make up a reasonable answer as to why we don't have to do the same with buses which aren't used much?
I suspect your boat was in a warmer and more humid environment than most of our buses are stored in. I also suspect when you ran your boat you did not run for hours on end, depleting the fuel and refilling. It is likely your fuel in the boat was on average much older than the fuel in the typical bus.
You may well be right We had 2-250 gallon tanks and with a Ford Lehman marine engine, fuel consumption was somewhat lower, relative to storage capacity.
The other factor was that a portion of the fuel line was rubber hose. In that application, it sucked a small amount of oxygen into the engine, causing injector clogging. I replaced the rubber hosing with copper tubing and solved that side of the problem.
So then it makes sense that warmth, humidity and age of diesel fuel are the factors in bacterial growth?
Or am I missing something here?
Warmth, humidity and age of fuel are the exact factors that promote the growth of crud in diesel (or Jet A) fuel.
I believe the new sponsor at Prevost-stuff has a fuel polishing system that they offer for buses. You'd have to check out their site... could have sworn I read something about it there.
I've never heard to anyone adding one to a bus.
Jeff, Jon, Ben - interesting subject. Diesel contamination generally takes three forms - biological (bacteria and molds), inorganic ( grit, clay, sand or dirt known collectively as asphaltene), and water. You would be amazed where the water can come from, including the refining process, particularly associated with ultra-low-sulphur fuels.The more sophisticated our engines become (electronic, high pressure fuel injection, etc), the more critical this issue becomes.
Fuel filtration and fuel polishing are related but measurably different. The issue is not just clean fuel and the impact it has on injectors and the engine itself, but fuel tank corrosion from the sludge/water in the bottom, and a host of new issues regarding bio blended diesel as well.
We have just published a comprehensive tech article intitled "Fuel Filtration...the key to engine reliability". You will find it in the February issue of Passage Maker Magazine (in the boating section of your favorite book store), or log on to our website at Zimmermancoach.com, fill out the contact form, request a copy, and we will mail it to you.
its not just boats. the original bio problem was discovered and written up in an app note from alco diesel, the diesel electric train locomotive guys. while i was an indentured servant in the '70s, (dam, i'm gettin' old...) we used some stuff called biobor to kill the little vermin that live in the oil/water interface.
i would assume theres something equiv for our tanks - anybody use anthing special?
anybody ever try to drain the bottom sludge out?
wmm
I don't know much on this subject, but I use agri-diesel, its a fuel additive from fuel power. To keep diesel from doing bad things....
I just bought the Feb issue of Passage Maker a few days ago. It's nice to know that their contributors are starting to appear on the POG board. I'd love to live on a motoryacht whenver I decide to stop living on a Prevost.
Karl.... are you going to be at Trawler Fest in Stuart, FL? I might show up.
A simple solution to this problem is to design the tanks by putting the fuel P-U from a sump at the very bottom of the tank instead of running a tube from the top going down that stops just short of the bottom. That way nothing is allowed to accumulate at the bottom and any water or smutz thats in the fuel is immidiatly or continualy pulled out and through an external water seperator that can be easily serviced. I know Mac uses the tube going down from the top style and those guys have to watch things closer than those of us sucking directly off the bottom like Pete and K-W.
I'm no sientist but have been told that certian fuel additives actually allow you to burn the accumulated water in the tanks by attatching a few additional molocules to the water changing its structure and making it combustable.
As far as the bacteria issue? How about get out and use it more frequently:eek:
Adding water to fuel is a bad thing, but we northerners had to deal with it so on occasion we added fuel line anti freeze which was basically alcohol. The water with its antifreeze would work its way through the system and if the concentrations reaching the engine were small it would pass though the engine. The engine would stumble a little if a big slug of water reached it all at once.
The water could enter the fuel tank with fuel when refueling, but a lot of it was the result of humid air being drawn into the tank and the moisture content condensing.
There is not a pilot on this forum that is not sensitive to how serious water in the fuel is.
Ironically, around the mid sixties Olsmobile produced a Cutlass with a turbocharged engine and it had water injection to control the burn and prevent detonation.
Growing bacteria and getting moisture in Jet fuel is dealt with in aviation with an additive such as Prist.
Ben - Steve D'Antonio our VP and author of the article will be at Trawler Fest in Stuart, FL from Monday through Saturday. He will be delivering three lectures, a 2 day lecture on systems (electrical,generator, engine etc.), a morning lecture on running gear/props/shafts and an afternoon hands-on session about tools and failure analysis.
so, jon- where does one acquire Prist? if it works for jp5 it outta work for diesel, i would think. no?
do you put it in your bus tank? i've never considered it a problem with 4-wheelers because they run so frequently (i guess). but bugs is bugs. do you treat your bus diesel?
Bill & Jon - Prist is used in Jet fuel to prevent icing of suspended water particles. Prist lowers the freezing point of suspended particles to minus 46 degrees as found in the upper atmosphere. It is not a product used for non-suspended water. Also Prist dropped the required testing and subsequent certification as a microbiostat (means kills microbes) in 1994. There is some evidence that is does, but the manufacturer no longer makes this claim. Good for jets....not much use in a coach.
Do any of you guys have a recommended additive for bacteria etc?
John
John - Hmmmm.... we are very careful about additives (it's an upcoming article subject), because of the perceived panacea effect. It's better to remove the water (bio environment) from the tank with a drain, stripper tube or polishing system, rather than to treat it, an ounce of prevention... Having said that, if needed, our preference is for a product under the name of BioBor, available at West Marine and many auto parts stores.
On a different note, someone else mentioned replacing their fuel lines with copper. This is not recommended by the engine manufacturers as diesel fuel has a chemical reaction with copper.
Hope this helps,
I don't want to contradict Karl, but I probably use our coach about average or maybe a little more. Nevertheless it sits for extended periods, sometimes as long as several months. Water and contaminents have not been a problem.
We keep it in a garage so temperature swings are minimal, and except for pumping water into the tank when you refuel, the only other way it enters is through the condensation of humidity due to rising and falling temperatures. Above ground bulk tanks are perfect candidates for this type of water accumulation.
Having said that, we have had the Racor filter / separators on our coaches and I can say that in 17 years and around 250,000 miles of travel I have had about ten tablespoons of water evident in the Racor sump and that was all at once, one time only. I think the key is to keep the tanks full, buy the cheapest fuel because that is where there is the most turnover and therefore the freshest fuel, try to avoid refueling when the truck stop is getting a delivery and avoid truck stops that don't change the filters on the pumps regularly.
We have almost exclusively use Flying J and have not had problems.
And now for the rest of the story.Quote:
Originally Posted by Jon Wehrenberg
It has been stated numerous times that a certain member uses the B & P method of topping off fuel tanks, which 'releases' sludge and water/condensation each time he fills up. This method results in less concerns about fuel problems.
If by Band P you mean burp and puke that situation is still there, but under control.
I never fill on the driver's side which was the worst offender when it comes to puking fuel, and on the passenger side I never approach the nozzle unless I know the tank has a long way to go. I just let it shut off by itself and it typically spurts out a cup of fuel which will keep the side of the coach from rusting.
Jeff - Jon - you are certainly doing everything right to minimize your risk of water contamination and your results show it! Others may not be so lucky. I recently brought a coach out of Florida and after 700 miles the filter was about full of water and trash.
In addition, the refining method itself (particularly with ultra-low sulfer fuel) can have up to 1% water content by weight at the molecular level. Although water at the molecular level generally isn't the problem, it is emulsified and free water that does the damage to finely machined components like injection pumps,high-pressure common rail systems and injectors. The free water is at the bottom of the tank and can not be "burped out".
Monaco (the largest mfg of Class A's) just published an article to their owners regarding bio-diesel (5% bio) and the increased risk of water and other contaminates.....they said "for older engines, a switch to biodiesel could clean off deposits from inside the fuel system and send them into the filter". They recommend "carrying extra fuel filters". In addition Monaco said "Because water is more prevalent in biodiesel, it is more prone to fall prey to microbial growth...". They noted that in a motorhome a filter failure "doesn't always occur in the best area", unlike a trucker who stays on the interstate. These issues are not just with bio, but diesel in general. Fuel quality and filtration is becoming a more and more important subject for all coach owners to become aware of.
As I mentioned in a previous post, we have a very comprehensive article available.
We are in the process of de-fueling a ten year old tank and looking around inside....it will be interesting what we find!
Looks like the fuel puking problem on Prevosts (2004 and up) has been solved. I met a nice fellow this weekend at Percy Quin State Park in McComb, MS. He has a 2004 XLII Royale w/2 slides. I asked him about the fuel puking problem and he showed me the diesel fuel filler tube. It was about 2 1/2" in diameter; according to him - IT DOES NOT PUKE. He said that his 2001 Prevost Royale non slide did puke.
I invited him to join us in Sevierville, TN this April, and I also invited him to join POG.:D
First, regarding B&P, my '84 doesn't (or hasn't so far) done this, and my fuel door states not to fill it all the way.
Second, being a first time coach owner and fulltimer, I rarely drive my coach. I do a maintainence run once a month to a truck stop about 30 miles away and fill up, then return. Do I have to, or should I, do anything to prevent any fuel problems? Is what I'm doing good or bad?
Geoff