Ducati Monster Forum

Moto Board => Tech => Topic started by: SaltLick on January 29, 2009, 04:49:05 PM

Title: Washing out a gas tank...dupainter help.
Post by: SaltLick on January 29, 2009, 04:49:05 PM
ive got my gas tank off and need to get that last little bit of gas thats in there outta there. No matter what i do i still hear a little bit swishing around in there when i shake the tank.  I am having it welded (brazed whatever) so it needs to be cleaned out really well. Anyone know the steps i should take to clean it out?  It worries me that i cant get that little big of gas out of there. Should i say to hell with it and just put some dawn liquid in there and wash it out a couple of times? How do you dry it out? I want to make sure the tank dont explode on us. Is there no way to get that last little bit of gas out? Do you just let it sit til it evaporates?
Title: Re: Washing out a gas tank...dupainter help.
Post by: midlifeduc on January 29, 2009, 05:12:55 PM
soap and water a couple of times should get it. then if you can fill it up with water before you weld. the water will displace any fumes so it wont go boom. if you cant fill it up then vent with co2 or air. [thumbsup]
Title: Re: Washing out a gas tank...dupainter help.
Post by: Holden on January 29, 2009, 05:23:27 PM
if you filled it halfway up with water, wouldn't the gas float to the top? then drop a match in and watch it flambé... [laugh]
Title: Re: Washing out a gas tank...dupainter help.
Post by: rgramjet on January 29, 2009, 05:24:51 PM
Dawn might not be a bad idea, maybe do final rinse with hott water.  After you weld it maybe some alcohol and let it evaporate after swishing it around before you refuel.

Never done it before so Id ask an expert..
Title: Re: Washing out a gas tank...dupainter help.
Post by: ducpainter on January 29, 2009, 05:34:22 PM
Soap and water...

rinse...

let dry.
Title: Re: Washing out a gas tank...dupainter help.
Post by: WTSDS on January 29, 2009, 09:37:01 PM
Your welder should know - run live steam thru tank for at least 5 minutes,  or use auto exhaust fumes

Danger is there may be some old dried muck in the seams, etc. which may not wash out, and the heat of welding can evapourate off some fumes and bang.

Title: Re: Washing out a gas tank...dupainter help.
Post by: One Jay on January 29, 2009, 11:27:39 PM
there's not enough (volume) of gas there to go boom, so you really dont have anything to worry about. if whats in there does combust it will be like flicking on a lighter for a flash
Title: Re: Washing out a gas tank...dupainter help.
Post by: Jobu on January 30, 2009, 12:52:09 AM
Quote from: One Jay on January 29, 2009, 11:27:39 PM
there's not enough (volume) of gas there to go boom, so you really dont have anything to worry about. if whats in there does combust it will be like flicking on a lighter for a flash

Exactly.  Gas isn't explosive unless mixed with a lot of oxygen under pressure.

And I would listen to Ducpainter.  He's done it once or twice before (cleaned out a gas tank that is). 
Title: Re: Washing out a gas tank...dupainter help.
Post by: ducpainter on January 30, 2009, 04:45:30 AM
Quote from: One Jay on January 29, 2009, 11:27:39 PM
there's not enough (volume) of gas there to go boom, so you really dont have anything to worry about. if whats in there does combust it will be like flicking on a lighter for a flash
Maybe not boom...

but I've had them go ....

whooooooof....

with flames shooting out the sender hole.

The only time it's a issue is if there is heavy scale or sludge in the tank.
Title: Re: Washing out a gas tank...dupainter help.
Post by: red baron on January 30, 2009, 07:30:24 PM
Quote from: ducpainter on January 30, 2009, 04:45:30 AM
Maybe not boom...

but I've had them go ....

whooooooof....

with flames shooting out the sender hole.



Which is awesome he forgot to add. [thumbsup]
Title: Re: Washing out a gas tank...dupainter help.
Post by: rgramjet on January 30, 2009, 07:55:49 PM
Quote from: ducpainter on January 30, 2009, 04:45:30 AM
Maybe not boom...

but I've had them go ....

whooooooof....

with flames shooting out the sender hole.

The only time it's a issue is if there is heavy scale or sludge in the tank.

Saves ya money on chemical stripper!
Title: Re: Washing out a gas tank...dupainter help.
Post by: ducpainter on January 30, 2009, 08:11:58 PM
Quote from: trouble on January 30, 2009, 07:30:24 PM

Which is awesome he forgot to add. [thumbsup]
It's best if you have an audience. ;D
Title: Re: Washing out a gas tank...dupainter help.
Post by: SaltLick on January 30, 2009, 08:14:02 PM
Quote from: ducpainter on January 30, 2009, 08:11:58 PM
It's best if you have an audience. ;D

what is your guys experience with the chemical stripper (having the tank dipped) Does it harm the tank? Im thinking of having that done to get all the old layers of paint, bondo, jb weld, and clear coat off first before welding it.
Title: Re: Washing out a gas tank...dupainter help.
Post by: ducpainter on January 30, 2009, 08:21:57 PM
Quote from: SaltLick on January 30, 2009, 08:14:02 PM
what is your guys experience with the chemical stripper (having the tank dipped) Does it harm the tank? Im thinking of having that done to get all the old layers of paint, bondo, jb weld, and clear coat off first before welding it.
I personally dislike chemical strippers.

They get trapped in seams and screw holes with no good way to remove them and bleed out at the least opportune moment.

Do your brazing first and then have it blasted and epoxy primed.

You can do  your filler work over the epoxy.
Title: Re: Washing out a gas tank...dupainter help.
Post by: Gimpy on January 31, 2009, 12:25:49 PM
Quote from: ducpainter on January 30, 2009, 08:21:57 PM
I personally dislike chemical strippers.

They get trapped in seams and screw holes with no good way to remove them and bleed out at the least opportune moment.

Do your brazing first and then have it blasted and epoxy primed.

You can do  your filler work over the epoxy.

I'm no pro painter, but I haven't had that  problem with chemical strippers.  Guess I have something to look forward too.  When ever I have used chemicals it still seems like I am sanding for the same amount of time trying to get a good even finish.

So +1 on the blasting.

And media blasters from harbor freight clog and do not work well.   >:(