mysterious air bubbles in wvo
 

Hi everybody. First the backstory:
I have been running wvo mixed with diesel in various percentages, mostly 25-50% wvo for 3-4 years with many trouble-free miles. I get the oil from someone who makes tofu so it is very clean with no animal fat. First I let it settle for a week or two and I've never seen any separation/ junk collect on the bottom. Then I run it through two bag type water filters; one 25/10 micron next 5/1 into a 55 gal drum, where I pump off 6-8" from the bottom. Absolutely NO problems until :
Now, suddenly I have air bubbles visible in the clear line from the injection pump to the fuel filter (1982 300sd, single tank, all stock). There is no air in the fuel before the ip, I have installed a clear piece of fuel line before the inline filter- no bubbles. I have checked and re-checked all the clamps, sealing rings etc. If I drain the wvo and use 100% diesel the bubbles go away- no more problems. I've done this several times, the problem is in the wvo- not in the cars fuel system.
So I thought I had some suspended water in the wvo and I bought a centrifuge, band heater and insulation for the drum. Heat the oil to 180f (max that band heater gets it to) run the centrifuge a few hours, let it settle a few days, drain from the very bottom of the drum- no water. Put some wvo in the car-more air bubbles from ip.
If I heat up a frying pan and pour new, clean oil in it just rolls around very freely. When I pour my wvo into a heated pan it rolls around freely, has NO snap crackle or pop like it would if it had water in it BUT I noticed there are air bubbles in my wvo on the bottom.
Sorry for the long post but if anyone has any suggestions I'd love to hear them. Thanks in advance.

That sounds really odd. I have no suggestions, but will be interested to read what you finally learn. Good luck.

Does the car run ok when you use the WVO AND have the air bubbles? What I am asking is are the air bubbles causing the car to run poorly/fuel starvation? If not, what I would do is run it with the bubbly fuel but carry a spare jug or diesel just in case the car starts to run poorly.

I agree it is weird............. Has the place where you get the WVO changed brands of oil or what they are cooking in it??

Thanks for the replies and I should have described the symptoms better.
The car will actually start and run properly at idle and low power conditions only; there are no bubbles in the lines at this point. As soon as you get into the throttle and put a load on the engine it starts surging / cavitating whatever; now it's like it's starving for fuel and here is where I observed the bubbles in the clear lines from ip to fuel filter.
The wvo source has over the years been mostly soybean oil but sometimes they used canola, olive and others and I've never had a problem until now. She claims there is nothing changed or new in their process, but I gotta wonder if there's not something else that got in some of it (like a cleaning chemical or something like that). The wvo still looks fantastic, clear no sludge, I just can't use it right now.

could it be that after a few years of using WVO that some of the fuel lines are beginning to degrade and let air in? especially the return lines?
nevermind, i reread your post and you say the bubbles go away when running diesel. sooo i dunno

Air Bubbles in WVO.
 

First off, I have been running WVO as a primary fuel source for over 5 years. Second, why do you pump WVO from the bottom of your barrel? The best quality WVO comes from the top. Lastly, since you have heated your WVO AND used a centrifuge my guess is the problem lies in your WVO source.

May I suggest you try a secondary source of WVO and see if the bubbles appear again? This experiment should point you towards the solution.

IF you need suggestions for alternative sources, please PM me. I used to work for company that did engine conversions. I was their "WVO man" and have lots of experience in acquiring WVO.;)

greaseguy

actually it just occurred to me. what kind of primer pump do you have? supposedly the new ones are incompatible with biodiesel and wvo. perhaps theres an internal seal in the primer pump that's changing shape when you run wvo, but when you run diesel it settles back in again? just a thought

Your tank strainer filter is clogged.It idles well as it is not clogged 100%. When you are revving the engine, the lift pump is more powerful than you think and it is starved of fuel, so it pulls air thru the strainer gasket, hence the bubbles. It runs OK when diesel is added as it thins out the fuel a bit,

There are 2 ways to fix it.

1) Take the strainer out and clean it, and clean it well. It probably can be re-used.
2) Purge compress air thru the feed line from the engine side. This will dislodge the clog and good for a while, until it clogs again.

Good luck.

greaseguy: My pickup tube is about 6-8'' from the bottom of the barrel and it's been there for years never a problem until now. I have a drain valve on the very bottom of the barrel which I open periodically to let out any water/nasty collections ( but honestly, I've never seen any large amounts of any nasty accumulation, the oil looks very good). Good suggestion on trying other wvo, I'll have to think about that. Thanks for the offer of a PM to you. I might take you up on that in a few weeks or so if I don't get this sorted out.
sleepstar : I have the newer primer on the 1982 300sd, but I also have a 1987 300d with no primer and had the same symptoms with the wvo recently in that car as well :( Again, going back to diesel took care of that car too.
ah-kay: I thought that might be it too, so I took the tank screen out and it was just as clean as could be.
Thanks for the support, and I'll definately update my progress or lack of it.

OK,

It sounds like you have pretty much eliminated most of the fuel system as the cause, but I have not seen where you changed both fuel filters. I know you said the bubbles are in the lines from the filter to the IP, but first change your clear in line filter and see if that helps. If not, try the spin on filter.

If neither of them help. I would suggest this. Get a small 1-2 gallon jug, and fill it with Diesel. Take both the fuel supply and return lines in the engine bay and put them in the jug (basically you will use the jug as a independent fuel tank). Start the car and see if it runs ok on Diesel from the jug. If it does, then try the same thing with WVO and see what happens. If it acts up again, it will confirm it is the WVO, and eliminate everything from the car's fuel system from the tank up to the point where you connected the jug.

Keep at it, we will find the cause sooner or later

psaboic: Already changed both filters. I even went as far as removing the spin on filter mount and taking it to have it flourescent penetrant checked ( at work, for free). No cracks there, not the source of the air.
I also hooked up a separate jug under the hood with wvo and still had the problem. Didn't put diesel in the jug because the car runs like a champ with diesel in the stock tank, no air in lines, no problems.

Well, after re-reading all of the post and the story, I have to think it has to be the WVO.

Main reason is not only have you pretty much eliminated the entire fuel system as the cause, you said you are having the same issue with another vehicle.

I second what grease guy said, try another source of WVO and keep it entirely separate from any WVO you have previously collected.

Do you think you could have water in the oil? I picked up a jug about a month ago and let it settle. Today I went to use it and it looked great....clear, no separation or sludge in the bottom of the cube. So, I poured it into my big stainless steel pot and heated it on my propane fired turkey fryer stand. As soon as the oil got to about 180, it started to crackle. At 190 it started to pop, and at 212 it was at a rolling boil.

Bottom line.....my oil that looked perfectly fine was full of water in suspension. So, even oil that looks fine can be suspect.

The WVO has a much higher viscosity than diesel. When the lift pump does it's job, the thicker liquid doesn't move enough and air gets sucked in from somewhere. You don't notice this with diesel because diesel is so much thinner than WVO.

If you had water in the oil, you could see it. If you have enough water in your WVO, it looks like coffee with creamer.


I suspect that you have a fuel line leak. Rusty fuel line with a pin hole. doesn't suck air with diesel,,, YET, but it will.

I politely disagree with being able to see water all the time. Right now in my garage I have ten gallons of clear amber/gold WVO with no settlement line or separation. It has been sitting for weeks, and looks great, but as soon as you heat it over 180 degrees it starts spitting, crackling and bubbling. Go to 212 and you get a nice rolling boil along with the spitting.

Its full of water but looks fine

I think this right here tells you that its WVO problem and not a car problem. Some companies put odd stuff into vegetable oil to make it stay fresh and last longer. Maybe some of these additives are causing bubbles to form. Maybe your WVO source has changed their oil.