How do I keep diesel fuel from leaking all over the place?

[Bob&AnnaMari]

On our last trip we noticed some fuel leaking from the 30-micron filter/water separator. The Cummins shop we took it to was unable to get the right part to fix it so they bypassed the 30-micron filter and left the work to the 10-micron filter until we could get back to home base. I fixed the filter and now need to reinstall it. But, I cannot figure out how to decouple the bypass and reconnect the hoses to the filter without having diesel fuel leak out all over the place. Is there some sort of fuel shutoff that I should be able to turn off during the reconnect? I should have asked when they did the original bypass, but I didn’t. Any help on this is greatly appreciated.

(I hope this is the right forum since filters are somewhat of a chassis issue. If this is the wrong forum please let me know)

[nplenzick]

As long as the connection is higher then the fuel tank I would see no problem. It would be just like changing a fuel filter wouldn't it?

[Logthumper]

I would do as follows. This works while doing repair work on cooling systems hoses, replacing damaged oil drain plugs, oil lines, etc:

1: Insert a vacuum cleaner hose in the fuel tank opening. When the vacuum is running, the fuel tank will be under a vacuum (do not start the vacuum yet). A plug may have to be inserted into the fuel tank overflow in order for a enough vacuum to be created in the fuel tank.
2: Disconnect the fuel line from the filter, when fuel starts running, start the vacuum which will stop the flow and draw air from the filter location back into the tank. Make sure the connection from the fuel line to the filter is disconnected before creating a vacuum. You don't want to draw fuel from the second filter.
3: With a vacuum now in the fuel tank, you may now perform the necessary work at the filter. When you have the fuel line disconnected from the filter, you might want to plug the fuel line and shut off the vacuum while you do the necessary work.
4: Before reconnecting the fuel line back to the fuel filter, stop any vacuum and allow fuel to again fill the line to the filter. When the fuel again appears at the filter location, reconnect the fuel line to the filter.

That’s the general idea. If this doesn’t make sense, don’t do it.
Hope this helps.

[Happycarz]

Could you explain how to keep the diesel fumes out of the arcing brushes in the vacuum motors when doing the above. Or, do you use a 200' hose to keep the explosion away from you.

Vacuums have warnings about flammable vapors. Please be careful.

[Logthumper]

I'm not to concerned with diesel fumes (compaired to gas fumes). If I worried about every direction printed on every lable, I wouldn't take any of my medications (for fear of death) and would get rid of all my electrical equipment and mechanical equipment. Probably just better to not get out of bed.

All suppliers have to more than cover their *** in fear of to many people looking for an oppertunity to sue.

Its best to use common sense, I have made it thru 72 years so far by doing so.

We just have to use common sense in any of our efforts and don't proceed with any project your not confortable with.

Great pic.

[RVDude]

While diesel fuel is not as spontaneously energetic (flammable) as gasoline, my common sense (no discourtesy to logthumper's 72 years) is that the vacuum cleaner to the fuel tank method is insane. Vacuum cleaner to the radiator or crankcase sure. Vacuum cleaner to any fuel or other solvent, never. Unless you have a very special explosion proof vacuum - yes they do exist typically for laboratory uses.

Instead, if the line has a rubber hose component somewhere on it try hose pinch pliers.

[Logthumper]

I would not pinch shut a fuel supply hose with a hose pinch pliers, trying to do so could cause other fuel delivery problems later. Also I believe the hose is to solid to do so.

Why not just disconnect the fuel line hose at the tank location and then proceed with your repairs? Any fuel loss would be minimal and could be easily caught in a pan.

Great pic.

[Logthumper]

Just something to read and think about. I’m typing this so I didn’t blow my head off.

Everything interest me. My curiosity is always active. So this morning, just for kicks and feeling a little insane, I wanted to do a test of the spontaneous energetic (flammable) caricaturists of diesel fuel fumes as I would compare them to the spontaneous energetic (flammable) characteristics of gas fumes. As always use common sense, however what is common sense to me to achieve an end result may be uncomfortable for you, so then you shouldn‘t do it.

I took a 55 gal steel barrow with an open top. Placed a shop vacuum with open armature brushes in it. Inserted the vacuum hose into a 5 gallon container with diesel fuel in it (kept the hose above the level of the diesel fuel). Plugged in the vacuum and waited while the vacuum sucked diesel fumes out of the container containing the diesel fuel and filled the 55 gal drum with diesel fumes.

Did I expect an explosion? No

Did the diesel fuel vapors explode as they filled the barrow containing the running vacuum with the open armature brushes throwing sparks? No

OK, now lets cover the barrow and trap even more of the diesel fumes and again plug in the vacuum.

Did I expect an explosion? No

Did the diesel fuel vapors explode as they filled the barrow containing the running vacuum with the sparking armature brushes? No

Would I do this same experiment with gas? NO

Interesting experiment to me. Done under the proper safety conditions.
For me, I am satisfied that diesel vapors are not close to gas vapors as far as ignition of their vapors.

Does this prove anything? Not trying to prove anything to anyone, just satisfying my own curiosity and thought others might be interested in my experiment.

As I said before “If this doesn’t make sense, don’t do it.”

So don’t try this, you might blow your head off.

[RVDude]

log, your experiment is accurate (and actually rather safe). The issue in these forums (the public internet) for the average-Joe (or Josephine) is that "technically" vs. "in-practice" can differ without complete scientific understanding and controlled conditions. This post is to provide the scientific basis for your successful experiment and more importantly, the practical cautions against the vacuum cleaner to the *diesel* fuel tank practice.

First, let's clarify that "inflammable" is the same as "flammable" (they are NOT antonyms) is the same as "combustible." All three terms equally mean "can burn."

Now, a key difference between gasoline and diesel is "volatility" and more technically "flash point" the lowest temperature at which the vapors can be ignited. Gasoline being far more volatile (far lower flash point) and far more aromatic than diesel. In lay terms, diesel can be more tricky to ignite and gasoline is far easier to ignite.

Gasoline has a flash point of -40F (that's -40) meaning it's vapor can be ignited (using a spark or something) as low as -40F. Diesel has a flash point of 144F meaning the vapors have to be over 144F to ignite with a spark. Hence, the generally safe aspect in using/storing diesel fuel. Diesel vapor will not ignite at room and typical environmental temperatures - unlike gasoline vapor which will.

In your experiment, assuming only diesel fumes (vapor), you'd have to heat those fumes in the vacuum cleaner over 144F before the motor brushes could ignite it. **At room temp, you can not ignite diesel fumes (vapor).** Gasoline vapor on the other hand would go off like a roman candle at room temperature.

Note that fumes (vapor) does NOT behave the same as atomized (liquid) particles. Hence, we next focus on the real "why you shouldn't try this at home" issue. Note again we have been talking vapor (NOT atomized liquids), but pure vapor.

If that vacuum cleaner were to inhale some actual liquid diesel and atomize or nebulize it as it bounced along the corrugated vacuum cleaner hose those atomized particles of diesel entering the arcing brushes would make for an interesting 911 call. Guaranteed.

Here's the gist. While gasoline vapors will freely ignite at room temperature diesel vapors (at room temp) will not ignite. Your experiment showed this clearly. However, ATOMIZED liquid diesel WILL freely ignite at room temp. All you would need is introduce some liquid in your vacuum setup and have that liquid get atomized as it bounces down the vacuum hose or is splattered by the motor armature and poof, up in flames. Add to that initial (liquid based room temp) ignition the resulting increase in temp above the vapor flash point thus now allowing the vapor to enter the combustion sequence as well.

Igniting atomized liquid is how oil furnaces and (diesel) AquaHot systems work, and, without getting overly technical, igniting vapors (through high compression heating above auto-ignition temp 410F) is how a diesel engine works.

So, in practice in the home shop, you can NOT guarantee that there is NO liquid/atomized diesel in the vacuum cleaner used to pull a vacuum in a diesel tank. Or the accidental use of the technique on a gasoline tank. Hence the reason I have to call this practice highly undesirable.

To be fair, and as demonstrated by your 72 years and your experiment, the chances of a vacuum cleaner pulling raw *diesel* fuel AND it subsequently atomizing in the vicinity of the motor armature (the ignition point) is probably somewhat low.

Until, of course, that one time, when the vacuum hose is accidentally pushed to far into the filler, the tank is too full, or the filler tube breather happened to be full of diesel fuel, or someone tries it with a gasoline tank, or, or, or.... Those "or"s can kill you. And why I would strongly urge folks NOT to try this practice. Instead, use hose pincher pliers, that's what they are made to do and they won't harm you (good condition to begin with) rubber hoses.

Kind of like crawling under you coach using only the HWH jacks to lift/support it. Yep, it's done all the time and the chances of disaster are low, but when a hydraulic line breaks, oh well....!

Nice experiment, thanks for sharing!

[Logthumper]

RVDude: “Igniting atomized liquid is how oil furnaces and (diesel) AquaHot systems work, and, without getting overly technical, igniting vapors (through high compression heating above auto-ignition temp 410F) is how a diesel engine works.”

I agree with you. A good thought out plan is always the best first step. However after thinking about it for a while, if it appears feasible, I usually take the approach of “Lets light the fuse, get behind something and see what happens”. Guess that’s why I like the TV Show “Myth Busters“. Still have all my fingers and toes, although came close to losing a big toe when I shot myself.

Thanks for the info in your feedback.
　

[a k]

Boy, I'd hate to have to bleed that system when it's done.

And ,besides that, I don't think the motor part is exposed to fumes from a shop vac.

I'd use my wifes thumbs over the lines while I installed it.

[Happycarz]

Also, for the fuel to ignite, it has to approach the stoichiometric ratio to burn. In the case of diesel that is 14.6:1. Yes, it will burn above and below that exact ratio, but not by much.

[Bob&AnnaMari]

Thanks folks for all the suggestions. I think I will just move the unit to a hill where the filter is higher than the fuel tank. I think this option is a bit simpler.

Thanks again,
Bob Stokesbary
2003 Beaver Patriot

[dieselclacker]

Much adiu about nothing.

Dieselclacker