diesel fuel storage??

Again science vs practicle use. 100 years of trucks and tractors back my recommendation, and I do not doubt 100 years of science backs yours. The reality is that your way will work better, but does it need to. My car runs fine on regular gas. Premium would make a difference, but not enough to justify the cost. For many, that is not the case. You clearly have far more background in chemistry than I do, but practicle application allows far wider tolerances. I have run diesel that is far more than 6 months old in tractors with no noticable change in performance. I have had steel tanks that were 30 years old with no rust in them as a result of being kept full all the time. And if I read your post right, are you saying water vapor will combine with diesel fuel? My understanding is that oil and water do not mix, but I will accept the chemistry lesson if I am wrong. Please let me know on that one. Not saying you are wrong, but just more particular than is necessary for this application.

[Richhh]

Actualy water in fuel - to certain limits - is a good thing.
The water cools the flame propagation acting as if the diesel fuel had a higher cetane number or gasoline had a higher octane number.

Water and oil or not miscible. An emulsion is the dispersion of fine droplets of one fluid into another fluid where both fluids are not miscible. Most emulsions are quite stable. Movement of immiscible fluids, such as pumping, or overflow into a return line causes the mixing. Unless the fuel is kept very hot (as in a crankcase), there will be lots of (not free) water in emulsion form.
Sure, you ran fuel that was over 6 months old, everyone does; but, did you ever actually look for and see the actual decomposition results - particle growth via cloudiness of the fuel, the dropout of particulate on the tank walls, etc. etc. etc. etc.

Trucks dont have a problem because they are constantly consuming and replacing the fuel; plus, they usually buy fresh fuel from a high turnover source.

On my boat I run a huge black iron tank. I have complete confidence in its integrity and the integrity of the fuel .... and thats why I do what I do. Im not being super cautious to a fault but simply have inherited severe fuel fouling problems and choose not to have them. I even have an onboard recirculation/polishing system with a gravimetric water knock out pot ... and a separate small gravity feed day tank, so that *everything* goes to hell I can still operate at will for about 3 hours.

Unless you keep the temperature of the fuel very hot you will sooner or later have a free water problem. My choices are quite cheap to insure stability and reliability.

[Alan Wheeler]

Sorry Richhh, I have to strongly disagree. Water in Deisel fuel is NOT a good thing. Firstly, it takes very little water to stop and engine dead. It just robs the burn of heat and it will stop the combustion process from accuring. Plus..
Tremendouse damage can result in even the tinyest amount of water entering the injector system. Apart from abrasion to high pressure pumps, when the water enters the injector nozzel, it litteraly explodes (it instantly expands to 7 times it's original volume) and will chip the ends of the injectors. This results in poor spray patterns that in turn, can lead to poor engine performance and most dangerousely, the spray pattern can be caused to fire in a direction that allows fuel to burn around valve heads and piston faces. This results in hot spots and can destroy those parts. Also, when sprayed in the wrong area's, the fuel does not burn correctly and tends to harshly detonate in those localised area's instead of over the normal larger area and in the designed controlled burn. So even though on one account, the octane rating may be changed for the better, shockwaves from incorrect detonation will cause untold more harm to the engine. You also lose power, because instead of the longer controled burn giving the engine Torque, you get a shorter burn time, resulting in less power stroke and poorly burn't fuel, thus the smoking engine a sign of bad wear. All from a few drops of water.

[Richhh]

Alan - What a combustion engineer would refer to to is the non-FREE water, water that is typically in emulsified form and finely distributed among the molecules of fuel. Free water is what a person can 'noticibly SEE'. Water (not free water) will help depress the flame speed, reduce knock by effectively and aritificially raising the octane number in an ignition engine. The benefits are derived as the unburned water allows the engine to aspirate a leaner mixture, since less 'over-fueling' is needed to cool the combustion chamber .... yup, unburned fuel is needed to help cool the combustion chamber. Typically an engine power output optimizes when 10-15% overfueled. Alcohol-water mixtures have been injected into the intake manifolds of large super-charged prime mover engines for knock supression AND power improvement at single speed operation, etc. .... since they've been making engines.

I used to race sprint cars and used methanol as the fuel and also used water injection into the manifold to help optimize and control hp output at very radically advanced ignition timing. BTW For maintenance purposes, nowadays I simply on a routine basis periodically very slowly dump a mixture of water and either transmission fluid or Marvel Mystery Oil (castor oil based) into the throttle plate to clean out all the carbon from -- piston tops and piston ring grooves, valve stems, exhaust manifolds (including water injection elbows, etc.) ..... blows the 'crap' out the back end and I never need to do a 'carbon job'.

FREE water is water that is 'noticiable'.
Emulsified water is mixed with the fuel - in a very finely divided / macroscopic state ... something like a 'suspension'.

Water can be a 'goooood' thing. Ever wonder why your automobile runs better on a cold, wet, humid day? Its the water.

regards

[Alan Wheeler]

Hang about, we are getting confused between Deisel and Petrol engines here. Sure, water injection has been used in Petrol and "top fuel" engines since Adam was a Cowboy. But NOT in Deisel, at least not via the standard high pressure injector design. And I have never seen nor heard of it ever being done in Deisel engines.
Water, even in Molecular size, will damage the tips of injectors.

The other point is water injection, even in vapour form from a cold foggy night as you described, works in high temperature fast burning fuels, but Not Deisel. Cold air, thus being denser, thus getting more air into the cyclinder, is the majic behind a Deisel increasing performance, but allow even water vapour in Fogg form into that deisel, and the performance drops. The reason why, Petrol is ignigted by spark, Deisel is ignigted by heat from the compression of the air in the cylinder. Even the smallest amount of water in the Deisel cyclinder robs the combustion cycle of much needed heat and results in an engine running as if it was low on compression. Water injection into Top fuels does increase power. It decreases the rate that the fuel burns, thus creating a longer power stroke and thus more torque. The fact that Deisel burns slowly, is why Deisels are inherintly more torquey motors and also one reason why you can't get the very high RPMs out of Deisel. The fuel simply doesn't burn fast enough.

[cadye]

This certainly seems to be a subject with a lot of different opinions. Now, one just has to decide who is right !!?
Looks like I won't be launching this year, so my tank is full, stored inside a heated building, 45deg f min , I have turned to engine over for 15 sec, to get the oil up and move the pistons. Hope all this is adequatefor 16-18 months storage.
Thanks for all the info.

[Alan Wheeler]

Well to keep it clear and simple. Firstly, with Desiel, No water! no problem. So ensure tank is clean if you can. If you can't, put an additive into the tank that has a Biocide in it, to stop any possible algae growth. I would do this anyway, even if tank is clean. If available in your area, a product called "Fuel Set" is a good choice, because it mixes with water and does two things. It turns the water a milky white you can easily see and it emulsifies the water and stops, or I should say reduces the ability of the water from rusting the bottom of a steel tank.
That's the the Fuel taken care of.
Now the Oil. Put an Oil flush into the engine and run it to ensure more contaminant is flushed out. Empty old Oil out and allow to drain well. Overnight is not a bad Idea if you can, but just drain as long as practicle for you. Then fill with a good quality Oil, Synthetic or Part Synth is good for a good coating on parts out of Oil bath. Run engine for a few minutes to allow Oil to coat everything and shut down. That's the KISS approach. If you really want to mothball the engine, there is a set procedure with special fuel oils, but it is complicate for most none Mechanicly inclined people to carry out. I wouldn't worry about it. Unless you really want to know. Just ask and I will run through it.