Vacuum powered fuel transfer?! - PeachParts Mercedes-Benz Forum

nickofoxford · #1 10-01-2008, 05:37 PM

I came up with this idea after 10 or so tankfuls of transferring diesel into my car from a tank I have in my garage. I have a 5 gallon gas can and I make 3 trips to fill my car up. The gravity fed tank takes forever so I usually walk away and do something to find the vent on the 5 gallon tank spewing diesel..

I wanted to originally buy a transfer pump, but $80 for a pump, pshhh. So I began wondering how to use something on my car to do it. Then it struck me, VACUUM! It's everywhere on the car..

So my 1980 240D has a bad trunk lock actuator, and the lines are still there (and BB'd) This is what I figured I could do. Why not apply vacuum from the system to my 5 gallon tank, then suck the diesel right out of the tank? Well I realize I am limited to one fillup, but I can do that every few days instead of putting it off until I have to do 3 tankfulls. I also know that it's only going to work if I am on the right line and I have the doors locked/unlocked, but that's temporary I can tee the resevour if this works.

So what thoughts are surging your mind? Two things came to me, what will diesel vapor do to the vacuum system? Also, my vacuum pump vents into the air cleaner, not the crankcase. But diesel vapor shouldn't noticibly add fuel to be combusted, right?

So I was thinking hook the tank up in the morning, drive around do what I gotta do, come home and fill 'er up. Sounds feasible doesn't it?

Heres the basics, My 5 gallon tank hooked through the little vent into the vacuum system. Vacuum is applied and the vacuum system disconnected from the not-tank-side of the check valve. The "filler" hose is attatched to the big tank and the valve (not pictured) is opened on the "filler" line to allow the diesel to be "sucked" into the vacuumed tank.

Heres a little diagram for you visual people like me:

PatricdeBoer · #2 10-01-2008, 05:43 PM

I think the main problem with that idea is that you might distort/collapse the fuel tank. It doesn't take too much vacuum to do (can happen if the tank vent is plugged) that and the tank isn't really design for those kinda forces

*edit* Hmmm, upon re-reading your post, I'm a bit confused as to which tank you are using for what.

nickofoxford · #3 10-01-2008, 05:52 PM

Yeah I though of that too, It's an older thick plastic 5 gallon tank. What I want to do is pull the fuel out of a huge diesel tank in my garage and move it to my fuel tank. Right now it has diesel but soon it will be my holding tank for biodiesel. The big tank is probably 300 gallons or so. So the little tank will be doing the traveling, the big tank is just my fuel "buffer".

nickofoxford · #4 10-01-2008, 05:54 PM

*more editing* I will not actually be using my cars fuel tank for any of this. Now I see how I confused you. Imagine there is a 5 gallon plastic tank instead of the square on my wonderful drawing

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mobetta · #5 10-01-2008, 06:31 PM

If you are using Bio, you can use a cheepo 1" 110v water pump from northern tool, harbor frieght,etc.- $40+ hose& fittings. not sure I would use it on diesel, might be fine.

I use a barrel pump to pump fuel out of 55's into a fiver then into my car.

your plastic can will prolly collapse. it doesnt take much.
another option is use a bbq grill tank. they will hold vac.
but the main issue is that your car will only draw so much vac- like 15-18" , so the container will run out of "suck" before it is full.
I use a 25 gal vessel to collect used cooking oil, and if I pull 28"ish(max) on it, I can collect about 22 gals before the flow stops.

nickofoxford · #6 10-01-2008, 11:29 PM

Mobetta,
Sounds good, I actually have a propane tank I can use and a 12v axillary vacuum pump for my trunk. Should make a nice setup. Basically the fewer moving parts and lifting tanks, the better.

Here's the kicker, has anyone seen a tank shaped like a spare tire? I know I've seen one on the web somewhere and now I can't find it anywhere. That would make a really nice two tank biodiesel setup.

turbobenz · #7 10-01-2008, 11:41 PM

i think it would work but you cant pull a high volume of vacuum from these cars. You'd have to wait awhile for it to be full.

Im thinking of using engine vacuum to pull a vacuum on the ac system of a car im working on. I figure its better than nothing

mobetta · #8 10-02-2008, 09:54 AM

Quote:

Originally Posted by turbobenz

i think it would work but you cant pull a high volume of vacuum from these cars. You'd have to wait awhile for it to be full.

Im thinking of using engine vacuum to pull a vacuum on the ac system of a car im working on. I figure its better than nothing

you can make a vac pump out of an old fridge or AC compressor, too. it will pull way more vac than an engine vac pump, and you can run it for a few hours for a few cents.

search super sucker on the greaser sites.

I have seen the spare tire tanks all over- many wvo conversion companies sell them, about $400.

patbob · #9 10-02-2008, 11:39 AM

Quote:

Originally Posted by nickofoxford

Yeah I though of that too, It's an older thick plastic 5 gallon tank. What I want to do is pull the fuel out of a huge diesel tank in my garage and move it to my fuel tank. Right now it has diesel but soon it will be my holding tank for biodiesel. The big tank is probably 300 gallons or so. So the little tank will be doing the traveling, the big tank is just my fuel "buffer".

Your diagram shows a check valve on the vacuum line. Why not put that on the tank vent of your existing gravity fed system to prevent it from overflowing and dribbling diesel? Lots simpler.

Alternatively, you could get a diesel dispensing handle -- like the kind on the gas station pumps -- and connect it to your 300 gal tank. I saw something like that at my local farm & fleet store (a Costal) last time I was in there. I don't know if the ones they sold had automatic shutoff or not, but with that big of a hose, it probably wouldn't matter. They might even sell electric lift pumps for the diesel tank, but you'd have to look.

As for the vacuum idea, you'll be sucking diesel fumes through the vacuum system, which will probably degrade all the rubber parts they touch faster. Other than that, I don't think the vacuum pump is designed to do large volumes of air, so you'll probably need to seal every pinhole leak in the setup to make it work.

nickofoxford · #10 10-02-2008, 03:09 PM

Thanks again for all the tips. I think im just going to go with a 12v pump of some sort. I don't really need the professional setup, I just need to get diesel 10 feet or so to my car so vinyl tubing should work for a while.

I like the old compressor vacuum pump idea

. I too have to vacuum my system sometime in the spring to get ready for the summer heat. But for now my almost instant heat shouldn't let me down. I love how my car heats up so fast