Plastic Tank problems: Discussion thread, see info thread sticky for updates

[ducatiz]

that's an interesting idea, but i believe that other components of the gasoline separate as well as the ethanol..  i don't know enough about it though, you could be onto something.

[sbrguy]

I hate to ask the obvious, but if your bike is going to sit a while, can you just drain the gas into a container, wait for the ethanol to separate, and then pour the ethanol free gas back into the tank, potentially eliminating the issue?

Then again, if you're going to go through all of that, you might as well just leave the tank empty, since its not going to rust internally like a metal tank might.

Sounds like it might be something to do for those who's bikes sit for winter storage, waiting for repair parts, or for any real amount of time? Might help reduce it, even a little bit.

BC.

what would be cool is do that in gallon or larger sizes in your garage and then sell the "ethanol/water" free gasoline to other ducati folks for 1-2 dollars more per gallon. 

[BK_856er]

The thing about liquids and their interaction with the solid world is that mixtures can behave very differently compared to the individual components.  Dry gas or dry gas with ethanol might not be a problem, but gas with ethanol and some (inevitable, variable) moisture could be a troublemaker.

I would not be surprised if you could fill the tank with either pure water or pure ethanol and there would be minimal swelling or distortion over an extended time period.  However, make a mixture of the liquids and it could be a whole different ball game.  I don't think separation of the liquid components due to solubility is a factor.  In fact, the presence of ethanol or other alcohols will increase the solubility of water in the mix (and that could be the root of the problem).

If someone can send me some virgin PA6 I will setup an experiment to measure the mass and dimensional changes vs. time in various liquids.

BK (yet another ducati riding phd chemist with two replaced tanks)

[herm]

so, now i need to retrain my brain to empty the tank instead of fill and stabilize when i put it up for the winter.....

[ducatiz]

I would not be surprised if you could fill the tank with either pure water or pure ethanol and there would be minimal swelling or distortion over an extended time period.  However, make a mixture of the liquids and it could be a whole different ball game.  I don't think separation of the liquid components due to solubility is a factor.  In fact, the presence of ethanol or other alcohols will increase the solubility of water in the mix (and that could be the root of the problem).

Already tested. 

Adding pure ethanol= no effect. 

Adding water (room temp) = slight effect (tank swells slightly after sitting for a week)
Adding water (90degF) = almost immediate effect.  tank swells almost immediately.
Adding water (150degF) = tanks swells up like a balloon within a few hours.

[BK_856er]

Already tested. 

Adding pure ethanol= no effect. 

Adding water (room temp) = slight effect (tank swells slightly after sitting for a week)
Adding water (90degF) = almost immediate effect.  tank swells almost immediately.
Adding water (150degF) = tanks swells up like a balloon within a few hours.

That's too funny.  Thanks for sharing those results.

BK

[Meerkat]

If someone can send me some virgin PA6 I will setup an experiment to measure the mass and dimensional changes vs. time in various liquids.

BK (yet another ducati riding phd chemist with two replaced tanks)

Glad to know I'm not the only nerd around here! Sounds like you're a strong believer in the "6 months at the bench will save you 6 hours in the library" philosophy. I haven't done an exhaustive search, but there has been some work done on looking at the effect of ethanol/fuel mixtures on PA6. I hope to get a chance to nerd out on this over the holidays so I can spew all sorts of literature-supported scientific goodness about what a crappy choice PA6 is for ducati tanks.

[arai_speed]

Looks like Girard Gibbs filed the suit:

http://www.courthousenews.com/2010/11/19/Ducati.pdf

[Howie]

I hate to ask the obvious, but if your bike is going to sit a while, can you just drain the gas into a container, wait for the ethanol to separate, and then pour the ethanol free gas back into the tank, potentially eliminating the issue?

Then again, if you're going to go through all of that, you might as well just leave the tank empty, since its not going to rust internally like a metal tank might.

Sounds like it might be something to do for those who's bikes sit for winter storage, waiting for repair parts, or for any real amount of time? Might help reduce it, even a little bit.

BC.

Besides the unknown aspect ducatiz stated, ethanol is one of the ingredients used to build octane.

[DRKWNG]

Looks like Girard Gibbs filed the suit:

http://www.courthousenews.com/2010/11/19/Ducati.pdf

And there we have it.  There have been a bunch of turds on .MS all screaming to put Ducati out of business because of this tank issue.  Pretty sad when you think about it...

[ducatiz]

Crap.  I guess they really put down the pedal. 

[DRKWNG]

If you read through the thread on .MS, I think the one guy who was so adamant about it might have been connected with the attorney's office. 

[BK_856er]

Glad to know I'm not the only nerd around here! Sounds like you're a strong believer in the "6 months at the bench will save you 6 hours in the library" philosophy. I haven't done an exhaustive search, but there has been some work done on looking at the effect of ethanol/fuel mixtures on PA6. I hope to get a chance to nerd out on this over the holidays so I can spew all sorts of literature-supported scientific goodness about what a crappy choice PA6 is for ducati tanks.

Greetings, fellow molecular nerd!  Yes, I try to avoid the library because I only trust my own findings.  My second PhD is from the School of Hard Knocks 

BK

[ducpainter]

Crap.  I guess they really put down the pedal. 

This is gonna suck for everyone in the long run.

[DRKWNG]

This is gonna suck for everyone in the long run.

It very well could.