Topic: Help with desrusting/decontaminating gas tank

[fendersrule]

Hi guys. Yes, another post about this.

The inside of my tank has some flaky rust, but it isn't bad at all.

I've filled the tank up completely with vinegar. It's been soaking for about 3 hours, and it already looks much better! In-fact, I'm not even sure if I should let it sit overnight because i bet in a few more hours it will probably look very clean. I also added some bbs to help dislodge anything that could be in there.

However, vinegar is not what you should end with because it will promote flash rusting almost instantly.

I have a gallon of POR 15's "Metal Ready", which is basically phosphoric acid and zinc.

I also have some alcohol that will help with drying, and a shop vac.

Basically, here's what I'm planning to do

1) Let the tank soak alittle longer with vinegar (with bbs) until it looks pristine inside.
2) Drain half of the tank. Shake it around and let the bbs knock around.
3) Drain the rest of the tank.
4) Flush with warm water and soap. Make sure all the bbs are out.
5) Add Metal Ready, let it sit for a couple hours. Swersh it around every 20 minutes.
7) Drain tank
6) Flush with warm water and soap, but this time add baking soda to neutralize the acid
7) Flush with Warm water again
Add some gasoline, "swersh" it around, and drain
9) Pour in some iso alochol, swersh it around, and drain.
10) Hook up shop vac and let it air out for....a couple hours?

Install. Keep using the fuel filter for a week or so, and then put a new one on.

What do you guys think?

[BobbyR]

Make sure you are not sucking the Alcohol fumes into the shop vac. I am sure you would not, I just had to say it.

[Jay Ace]

and work FAST in between steps. Rust will start forming literally in less than 5 minutes.

[phil71]

skip the shop vac. Bobby's right.. it can be trouble.
I like
C alcium
L ime
R ust
(toilet bowl cleaner) for tanks with flaky rust. It does wonders. Take something like a coat hanger and scratch around at the small crevices where the seams are. A lot of that rust you bust off will gather in there, and clog your petcock screen in a hurry. Then blow compressed air all over to try and get as much of the freed rust flakes as you can.  Shake, repeat. Wear goggles!

Also, the scare of flash rust is not something I'd be too worried about, unless it's really hot and humid where you are.  I wouldn't let it sit for more than a few days.. but you have time. 
   

[fendersrule]

Thanks Guys. I'm hoping to get this ready by tomorrow, but sounds like there's more involved, such as time! darn it!

I was planning on using my little portable vac that plugs into a cigarette lighter. Sounds like that's a bad idea with fumes? I'll skip this step.

I don't have a compressor, but I can head over to a friends house that has one.

Trick is, I don't know what "dry" is. It may "look" dry inside, but I have no idea if there's water/liquid on the seams. I'm also running low on patience because I want to ride.

CLR is similar to Metal Ready, I think. I believe both have phos. acid. With Phos. acid, you don't have to worry about flash rust. That's one of the pros about using it. I'll go out there with a coat hanger with the vinegar that's inside there now.

Problem is, I'm at the tail end of a resto, and this is the last step! Really want to be on the damned thing by tomorrow...

I'm tempted to just leave the vinegar in over night now, and begin the next phases tomorrow morning, which means start blowing it out with compressed air tomorrow at noonish. The question is, do I still let it dry out more?

[Vinhead1957]

Treat with vinegar and blow it out as best as possible and rinse it with gas.   And you should be good to go! I run with sea foam in my fuel to get rid stuff while you are riding.

[fendersrule]

Here's 4 hours of vinegar soaking.



Maybe I'm over doing this.

Proceed to next step?

Which now I'm thinking is flush it with warm soapy water, dump some metal ready in there, shake it around, let it sit for an hour (lets the zinc coat it), drain, dry it with air, rinse it with gas, and be done.

[Smoke Detector]

I used vinegar on my tank, rinsed with water, dried with hair dryer, and fogged with Wd40 - then it sat for nearly a year no problem. Since you are using right away, I'd suggest keeping it filled with gas and then maybe draining gas completely at end of season and letting tank dry out completely - so there is no chance the ethanol in the gas will degrade while sitting. Full tank of gas can't rust. My 2 cents.

[Vinhead1957]

If you are going to store a bike for say a winter leave the tank full with treated gas Stabol or Sea foam shut the petcock and drain the carbs. Mist the carbs and cylinders with mystery oil. Never had a problem in the spring.

[fendersrule]

Here's my process so far. Keep in mind my tank wasn't that rusty, but it could use a minor rust cleaning. There was some flaking, and some light spots.

I'm making this a 16 hour process instead of a 5 days process. It was very innefficient, but I feel that the results are going to be awesome. It's not a bad idea to wash the tank out with warm soapy water and a degreaser to begin the process, but my tank was bone dry so I skipped that step.

1) Fill with Vinegar. Let soak 4-5 hours. I don't think that any more than this is really that useful since the same application of Vinegar gets less useful over time. I see people leaving the same vinegar in for 5 days, and I really challenge this notion. I used straight vingar from the store, no diluting of water. This cost about $12-15 since the CB750 tank is large. If vinegar is all you are going to be using for rust treatment, then I feel up to 24 hours is really the maximum amount of time for effectiveness.

2) Let the tank drain. Swash it around, then let it drain completely.

3) FIll tank back up with warm soapy water (you can also add the bbs here if you have flaking). This is where you want to shake the $hit out of it.

4) Let the tank drain.

5) Stick a hose up to it and fill it up, swash it around, and let the water just run through the tank (rinse).

6) Fill the tank up with 1.5-2 gallons of water. Add 1 gallon of Metal Ready (POR-15) or CLR...both are very similar.

7) Swash is around every hour. Let it sit overnight (or for 4-5 hours). It's going to be overnight in my case because it's the evening.

---------------This is where I'm at now-------------------

Let it drain completely, carefully, and safely.

9) Rinse it with warm soapy water. Add some baking soda to make sure the acid is neutralized.

10) air it with a compressor

11) Add small amount of gas, shake it, and drain it.

12) Install it!

Where I'm at in the process now, I'd say the tank is just about rust free. Looks fantastic. I may be overkilling it, but it will be ready for another 40 years.

[Stev-o]

The pic above of your tank looks great. Get gas in it asap and keep it full as much as possible.

[bjbuchanan]

I would skip the superfluous steps now like extra soap and water, which will just promote corrosion. Dry it out with some acetone or alcohol because that will get the water out and be super dry and then swish around some 2 stroke oil, or what I use bc it is on hand, syn oil or just fill it right up with gas

After it is clean and dry just fill it up and be good

[RAFster122s]

Don't think the vinegar will cut the oil and varnish in the tank and a step added before the vinegar is probably a good idea to strip the oils and varnish. Then vinegar, then acetone or 90% iso alcohol wash followed by 2-cycle oil.  Keep the tank full of fuel and use Seafoam gas treatment. The fuel vapors will keep the rust at bay, thus the need to keep a full tank.

[Irukandji]

Needed to ask a question so bumped up an old thread related.

I have read most all the threads on this subject and may have missed something.
After a Vinegar treatment and baking soda wash,
As a last step in cleaning the tank could I use OSPHO wash (dont think it was ever mentioned) as the final step in rust prevention?
It is supposed to change any remaining partical rust to something  inert . So will it prevent the Flash from appearing with the coating left beind still be ok for the gas refill?

[martin99]

BobbyR who's the girl in your avatar? She's so distracting I couldn't read the posts!

[iron_worker]

Seems like a lot of extra steps to me if you're just going to be riding the bike right away.

I would just:

1) Clean the tank with some sort of de-greaser first if you have a lot gunk other than rust in there
2) Fill with vinegar and let sit for as long as it takes to reduce the rust (if it's heavy rust it might take some time)
3) Empty the vinegar, rinse with water a couple times (no soap ... it will take forever to get all the soap out)
4) Add a bit of gas line antifreeze (alcohol), swish it, then get out as much as you can
5) Fill it with gas to the top and run it. The water should be absorbed into the alcohol and will just be used up in the combustion process.

Optionally, you could use the metal ready or CLR after the water rinse step. The metal ready would leave a nice coating on the inside of the tank that would probably prevent rusting in the future. You could probably leave it sit without anything in it after that.

I personally think you're over complicating it a bit. If you're planning on using/riding the bike again right away then there really is no worry about it rusting if it's full of gas. If you're cleaning the tank out so you can send it to the painter then that's a bit of different story.

IW

[mrbreeze]

I just brought up an old post from 2005 about using muratic acid because I already have it on hand. Seems to be a harsher way of doing it so I will have to work faster than if I just used vinegar or phos. acid. I won't be putting mine into service right away so will treat it with a cup or 2 of ATF to prevent flash rust.

[Fatlip]

My tank was trashed pretty bad when I got it. I had a friend cut it open around the lid seam and sand blast it clean. There was a lot of rust flakes in there but he cleaned it right up and welded the lid back on. I bought an Eastwood kit off Amazon for about 35 bucks. They have really good reviews. http://www.amazon.com/Tank-Sealer-Motorcycles-Eastwood-10166Z/dp/B003HLE32A

Worked like a champ, did as he had some issues with flash rust but nothing too bad.

[mrbreeze]

I'm not going to get that carried away with a dentless tank but if it were dented up bad that would be a good way to go to both fix dents and derust while its open.I also would prefer to keep the original paint if possible.

[74750k4]

Hopefully the sand grains are large enough to get caught in the screen/filter. I can't imagine anyone/anything that could remove every last bit of that sand.

[Duanob]

Hopefully the sand grains are large enough to get caught in the screen/filter. I can't imagine anyone/anything that could remove every last bit of that sand.

Water pressure? If the tank is open just wash it out no problem. mineral spirits to clean and keep from flash rusting while it's welded back together. Although sand blasting is a bit extreme for such thin metal. Phos acid works like a charm.

After my last tank I have pretty good confidence I can fix just about anything. It had a failed liner, pin hole and rust galore and a few dents on top of everything else. I think it turned out pretty nice and serviceable again. BTW I used Caswells. I will probably only use it from now on until it fails me.

[flybox1]

+1 on the phosphoric acid.  love that stuff.
Kleen Strip Prep-n-Etch and a bunch of (free/old) golf balls (from the local range) is my go-to tank treatment.

[AintNoEasyWay]

Tank is looking great. If you wanted to go any further, I would do Prep N Etch as others recommend.

Air compressor may not get every bit of remaining fluid out. Acetone will take care of any little puddles still in your tank.

[mrbreeze]

Would Heet work instead of the acetone? Its alot cheaper than acetone and I would be using it in conjunction with compressed air and then misting it with ATF to store.