Interesting "Air In Fuel" Experience

[libbydiesel]

Several months ago I converted another gasoline powered vanagon to diesel power.  As part of the conversion I needed to clean out the fuel tank which had a thick layer of varnish/polyurethane goop from the old bad gas gradually evaporating over the years the van had sat.  I poured what I could of the sludge out of the tank and disposed of it.  I then used a gallon of acetone to thin the remainder down and clean it out.  I sloshed the acetone around for a while and then dumped it out and kept the drainings.  I then added a few gallons of diesel to the acetone/sludge left in the fuel tank, sloshed it around and drained it of and added it to the previous waste container.  I figure the waste container held approx 25% acetone and 75% petro-diesel.  When my fuel tank has gotten low, prior to filling the tank I have added a gallon or so of the waste fuel in order to use it up and then gone and filled up the rest of the way with pump diesel.  Week before last, I planned on filling up the tank of my rabbit and so I added a gallon or so of the waste mix.  Circumstances arose which prevented me from heading off to fill up with pump diesel and I needed to use the rabbit for a few errands.  I noticed that it was not running as well as usual.  I popped the hood and the clear supply showed solid fuel (no air) but the return line was filled with massive bubbles.  It looked like more air than fuel was exiting the pump.  I tried to track down where the air infiltration was coming from but everything was tight and appeared correct.  I figured it might be the mainshaft seal, but doubted it as the pump bushings are tight and I very recently went through that pump completely and changed out all the seals and o-rings.  I closed the hood and walked away without a satisfactory answer and decided to leave it alone while I cogitated.  A couple days later I had formulated a theory and so went out and decided to check a few things.  I opened one of the injector unions and a large hiss of pressure escaped.  I opened the others and they did the same.  I closed them up and started up the engine.  After the initial bubbles purged, the return line was clear fuel.  I then went for a drive to get the engine warmed up and popped the hood again.  Sure enough the bubbles were back in full force.  I then filled up with pump diesel as I had planned and the bubbles went away almost entirely.  There was still just the tiniest little bubble every once in a while.  All of this seemed to confirm my theory.  The bubbles were not air that had infiltrated into the fuel but rather with the higher concentration of acetone and and the volatile nature of acetone coupled with the heat from the engine was causing the acetone to vaporize in the pump, lines and injectors. 

[RabbitJockey]

thanks for posting thats pretty interesting.

did you ever light a paper towel with acetone on it.  this is something i do not recommend doing, but i was curious one day and tried it, with just a tiny amount wow!!!  that stuff burns.  like i said tho i don't recommend anyone tries it.

[R.O.R-2.0]

i bet the acetone made the seals leak temporarily...

Acetone is a HOT solvent.. it will eat anything.

[libbydiesel]

Acetone causing the seals to leak does not account for the pressurized gas situation in the injectors after they had cooled off.  Vaporized acetone, does.  Also, the bubbles stopped immediately upon filling up with pump diesel. 

[ToddA1]

Curious if you think any scarring occurred in the pump.  Many are concerned about the lack of lubricity in ULSD and add oil/additives to help and you added a strong solvent and gas...

-Todd

[libbydiesel]

It seems to run fine.

[Gizmoman]

To be honest libby, I am quite surprised you would put that stuff through anything you owned. I had to keep glancing at the avatar to make sure it was you

I recently drained my tank to change the plumbing under the van and have about eight gallons of "year old" diesel. I'll be dumping it into the local oil recycler's tank shortly as I have no intention of running it into my new filters, IP or injectors.

On the other hand, it is an interesting lab experiment (old gas+diesel+acetone = sludge with air bubbles and a poor running engine).

[libbydiesel]

I don't tend to run a lot of 'stuff' through my engine and in small ratios I haven't seen issues.  To be clear, I disposed of all the straight sludge.  When using stuff up like that I run it through my '79 Rabbit which is my "$100 car".  I drained 8 gallons of 16 year-old diesel from it when I got it going and did a similar 1:10 or so ratio.  It ran perfectly.  It was just a bit of a fluke that left me needing to use the car when it had the strong ratio in it.  Year-old diesel wouldn't bother me even the slightest bit.  Unless it's started growing algae then diesel is very stable unlike gasoline.  

I found your equation funny.    

[Gizmoman]

I don't tend to run a lot of 'stuff' through my engine and in small ratios I haven't seen issues.  To be clear, I disposed of all the straight sludge.  When using stuff up like that I run it through my '79 Rabbit which is my "$100 car".  I drained 8 gallons of 16 year-old diesel from it when I got it going and did a similar 1:10 or so ratio.  It ran perfectly.  It was just a bit of a fluke that left me needing to use the car when it had the strong ratio in it.  Year-old diesel wouldn't bother me even the slightest bit.  Unless it's started growing algae then diesel is very stable unlike gasoline.  

I found your equation funny.    

Understood. And thanks for the tip on the "old" diesel. It looks fine but it smells different than new so I just assumed, why take any chances. I'd save it and add in small bits as you suggested, but I need the jug to get new stuff in

BTW, "flukes" are the bane of us all

WHile I'm here, thanks for the bit on the stuck pump vanes (in another thread) requiring an "IP jump-start". Not that I need the info now but still a fine bit of info.

[One_punchmachinegun]

thanks for posting thats pretty interesting.

did you ever light a paper towel with acetone on it.  this is something i do not recommend doing, but i was curious one day and tried it, with just a tiny amount wow!!!  that stuff burns.  like i said tho i don't recommend anyone tries it.

Hahahaha...
This made me laugh so hard. Everyone around me just stared at me.
Not going to lie, now that you have said that. I really want to try it....

[ORCoaster]

Acetone has such a low vapor point I am surprised it didn't do damage to the return hoses at each injector.  Maybe you have something other than the 5mm black hoses in cotton jacket. 
We used to use acetone to drive the water out off all the chemistry equipment in the lab I worked in back in the day.  Not sure if that is still standard practice as it is really a known carcinogen now. 

I bet it was boiling up a storm at those injectors. 

[TylerDurden]

I recently went over the MSDS on Acetone and it is reportedly not carcinogenic.

Nasty enough stuff, tho:

“Harmful by inhalation. Vapours may cause drowsiness and dizziness. Inhalation of high vapour concentrations can cause CNS-depression and narcosis. Severe overexposure may produce more serious symptoms, including coma and risk of kidney damage. “

http://physics.utsa.edu/memslab/MSDS/Acetone.pdf

[libbydiesel]

My return lines (and all the other rubber lines) are McMaster c-210-a clear tygothane.  It is the most excellent hose I have used.  It is extremely resilient and clear so diagnosing normal air infiltration is easy.

While inhaling large quantities of acetone should be avoided (don't ever enter a nail salon...) it is actually a relatively benign solvent.  It is produced and consumed by the human body in natural cell metabolism. 

[ToddA1]

I was going to mention that it can't be too harmful, as it's used as nail polish remover.  I use it to flush my AC systems because it's a great solvent and it's cheaper than typical AC flush.

-Todd

[ORCoaster]

Sorry misinformation on my part.  I half remembered the risk to kidney damage and I thought it was known to be a carcinigin but it is NOT!

See here:  Carcinogenic (cancer producing) Effects
The one study conducted to investigate potential carcinogenic effects from inhalation exposure to
acetone by workers did not find any excess cancer incidence. There is no data regarding the
carcinogenicity of acetone in any animal studies. Chemicals similar to acetone have not been
found to be carcinogenic to humans. Acetone has been categorized by the U.S. Environmental
Protection Agency (EPA) as a Group D carcinogen (inadequate evidence to classify).


So breathe away.  Just don't strike a spark to the air.  Flame on would be next.