Dreaded alcohol/mtbe goo???

[jbjennings]

Being the paranoid wacko that I am, I just noticed this stuff mentioned in a post. I live in Louisiana and sometimes I notice (because I'm paranoid and check it often) that there is a little dab of brownish syrupy looking stuff in my tank every once in a while. I noticed this after cleaning out my tank just a few days earlier. I never pay attn. to where I buy gas. Is this brown stuff the infamous alcohol/mtbe goo mentioned? If not, what does it look like. I live out in the country and only have a couple of choices where to buy gas. How do you know if the gas has the alcohol or the mtbe stuff in it?
curious,
JBJ

 

[45Auto]

Re: Dreaded alcohol/mtbe goo???

The dabs of brownish syrupy looking stuff are usually water (from condensation in the service station tanks) with rust particles in suspension.

 

[Dhadley]

Re: Dreaded alcohol/mtbe goo???

MTBE was quietly taken out of the fuel back about 2001 (if I remember correctly). EPA didn't make a lot of noise about removing it, can't admit a mistake ya know.

45's most likely nailed it. Just try to get fuel with as little alcohol as possible (not easy to find out sometimes).

 

[Texasmark]

Re: Dreaded alcohol/mtbe goo???

On the MTBE, seems someone figured out that it causes cancer in humans....probably reason for the quiet exit.

Agree on the brown goo.

The goo I have had is "scuse the French" snot white, like nasal mucus and I only had it once and it was on a built-in tank that I had put some fuel stabilizer into. I do not remember the name of the product, nor what it contgained....just that it was a stabilizer for long term storage of fuel.

Now, here's what gets me. Isopropyl alcohol sold at the drug store for 39 cents a pint is pure isopropyl alcohol and purified water in some concentration of 50% or more alcohol. (Best I can tell that is a fancy name for ethyl alcohol, commonly known as ethanol, which comes from grain or possibly petroleum, not wood) So here we have alcohol and (diluted in) water and no gooey mess; just a clear liquid.

So what was the makeup of my gooey mess? Out of curiousity, I went out looking at some other alcohols (ethanol, methanol) and their uses and didn't really see anything about being used to absorb water. Amazed at their chemical differences, but all contain the usual organic ingredients, Oxygen, Hydrogen, and Carbon in varying molecular relationships. In the process I did find that alcohol dilutes in water.............Hmmmmm. Water is Hydrogen and Oxygen also. Seems reasonable that they would combine.

So now it looks like any water in your tank would be absorbed into the alcohol which is part of the gasoline and now you have diluted gasoline, not a gooey blob; or do you and if you do, what caused it?

I hope someone knowledgeable jumps in here and gives us a chemistry lesson. I really would like this confusion cleared up.....as, I'm sure, a lot of other folks would too......especially those trying to get the right recipe for winterizing their rigs.

Mark

 

[45Auto]

Re: Dreaded alcohol/mtbe goo???

Hi Mark,

Not a chemist here, but this comes from the Chevron website (http://www.chevron.com/products/PRODSERV/fuels/bulletin/motorgas/4_oxygenated-gasoline/pg2.asp). I would bet they've got some pretty decent chemists!

From the article below, I think the answer in a nutshell is that the ethanol and water are completely soluble with each other(as you said), but only partially soluble with hydrocarbons (gasoline). The higher the temp, the more water that can be absorbed into the fuel. But if it then cools down, the cool fuel can't hold all the water that the hotter fuel could so it separates (same reason you get condensation on cold surfaces - cold air can't hold as much moisture as hot air).

I think the separated mixture when it cools is what gives you the gooey blob and the reason the water isn't just suspended in the fuel.

Water Tolerance

Conventional gasoline, depending on its aromatics content, can dissolve up to 150 parts per million (ppm) water at 21?C (70?F). Oxygenating gasoline with ethers can increase water solubility to 600 ppm. Contacting either conventional gasoline or ether-oxygenated gasoline with additional water will not affect the properties of the gasoline but can make it hazy in appearance.

Cooling water-saturated blends turns them hazy because some of the water becomes insoluble. However, the water that is released does not contain much ether and there is not enough water to cause performance problems.

The situation is different for gasoline oxygenated with 10 vol % ethanol. The gasoline-alcohol blend can dissolve more water (6000–7000 ppm at 21?C/70?F). When this blend is cooled, both the water and some of the ethanol become insoluble. Contacting the blend with more water also draws ethanol from the blend. The result, in both cases, is two layers of liquid: an upper ethanol-deficient gasoline layer and a lower ethanol-rich (up to 75% ethanol) water layer. The process is called phase separation and it occurs because ethanol is completely soluble in water but only marginally soluble in hydrocarbons. After phase separation, the gasoline layer will have a lower octane number and may knock in an engine. The fuel also is less volatile. The engine will not run on the water/ethanol layer. As the concentration of ethanol is decreased, the aromatics content of the gasoline is decreased, and as temperature is decreased, less water is required to cause a phase separation.

The potential for phase separation requires that gasoline oxygenated with ethanol not be exposed to water during its distribution or use in a vehicle. Because of this requirement, gasoline oxygenated with ethanol is not transported in pipelines, which sometimes contain water. Rather, the ethanol is added to tanker trucks at the terminal immediately before delivery to the service station. Housekeeping at the service station is very important to prevent water contamination. This water sensitivity also means that extra care should be taken when gasoline oxygenated with ethanol is used as a fuel for boat engines. Ethanol blends are hygroscopic (absorb moister from the air) and in time can phase separate during storage if the tank is vented to the atmosphere and is subject to breathing as a result of temperature changes.

 

[Chris1956]

Re: Dreaded alcohol/mtbe goo???

This year is the first for NJ gasoline to have the 10% alcohol. Last week I was draining the 50::1 mix out of my boat tank, and some of the fuel had a cloudy look to it. Normally the fuel is a clear blue-green color. The cloudy stuff was the same shade of blue-green as the clear stuff.

I think it likely that water was making the fuel cloudy, but since water doesn't mix with the two-cycle oil, I assume the alcohol mixed with the oil and the water, giving the blue-green cloudy mix. Anyone else see this? I have put some of this aside to see if the water seperates out. Is there any way to know if the water content is small enough to burn this stuff safely?

 

[45Auto]

Re: Dreaded alcohol/mtbe goo???

Hi Chris,

Sounds like what you have is the water-saturated fuel described in the second paragraph of the quote from Chevron in post #5 - hmmm, easier just to re-quote!

Cooling water-saturated blends turns them hazy because some of the water becomes insoluble. However, the water that is released does not contain much ether and there is not enough water to cause performance problems.

As long as the stuff hasn't completely separated into a puddle at the bottom you're fine. The water it is capable of keeping in suspension isn't enough to affect anything.

 

[Lone Duck]

Re: Dreaded alcohol/mtbe goo???

45Auto;
Nice write up. I agree with most of it. Just to let you know . On cold canadian winter days , we used to put isopropyl in our chain saw gas to stop the carb from iceing up at -25(-10 F ) because of moisture in the fuel. At one time we used methalhydrate and found that in time it rotted the fuel lines and diaphrams in the carb. 1ounce to a 21/2 gal tank. Then we got smarter an ran hot air off the cyl over the carb. Then the manufactors ran a little heat pad between the carb and intake. I was told once that if you put too much in mixed fuel the oil will curddle don't know if that is true. At 40 below the boys still use isopropyl.

 

[Texasmark]

Re: Dreaded alcohol/mtbe goo???

Thanks 45. Might want to peek at the EPA comments in the "The Battle is ON" thread above. These folks are on the same sheet of music.

Looks like nothing is free. Ethanol seems to be a cleaner solution to environmental problems associated with motor fuels, but has it's problems which we'll have learn to live with.

Mark

 

[jtexas]

Re: Dreaded alcohol/mtbe goo???

How do you know if the gas has the alcohol or the mtbe stuff in it?
curious,
JBJ

they're supposed to have a big black notice on the pump "MAY CONTAIN UP TO 10% ETHANOL" or similar wording

 

[Texasmark]

Re: Dreaded alcohol/mtbe goo???

Just one final comment out of me. I mentioned before that I was really curious how you get the milky stuff since isopropyl alcohol you get from the drug store has up to 50% water, yet is clear.

A test I ran in the bathroom the other day was over 90% pure alco and I put some in a container with tap water and other than swirling around I saw no color change.

What these articles pointed out, (I think) is that you have to saturate the alco and add more water to get the milk and goo. So I guess what was confusing me was that the drug store alco/water combo wasn't saturated.

I can see how they can combine in solution since both contain the same chemicals.....just a different molecular arrangement.

Later,

Mark

 

[v1_0]

Re: Dreaded alcohol/mtbe goo???

Just one final comment out of me. I mentioned before that I was really curious how you get the milky stuff since isopropyl alcohol you get from the drug store has up to 50% water, yet is clear.

A test I ran in the bathroom the other day was over 90% pure alco and I put some in a container with tap water and other than swirling around I saw no color change.

What these articles pointed out, (I think) is that you have to saturate the alco and add more water to get the milk and goo. So I guess what was confusing me was that the drug store alco/water combo wasn't saturated.

I can see how they can combine in solution since both contain the same chemicals.....just a different molecular arrangement.

Later,

Mark

Wouldn't the cloudyness be in the gas/alcohol/water mixture, not alcohol/water - since the alcohol/water is only partially soluable in gas. ?

 

[Mark42]

Re: Dreaded alcohol/mtbe goo???

This goo stuff alone is good enough reason to siphon the tanks dry for storage. No gas, no alcohol, no water = no problems.