Author Topic: Tank rust woes  (Read 1125 times)

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Offline Zax

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Tank rust woes
« on: September 29, 2014, 08:12:26 PM »
So I did the nuts and fixture chain / hot water and dish soap fill shake like a mad man for hours and rinse for a few nights (have a scar on one ankle to remind me)  then dropped a couple hundred bucks on a pail of metal rescue and filled up the tank to get then remaining rust taken care of. Rinsed it and immediately filled it with fuel. Now a year later the tank is full of rust again. I am plugging up in line fuel filters like crazy and having all sorts of fuel delivery and float needle issues now.

I am thinking now of the Electrolytic process. My question is do I have to line the tank no matter what I do to get it to stop rusting? I was hoping to not do a liner considering all of the nightmares I have read about with liners failing.

Thanks

Zach
1978 CB750F

Offline ekpent

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Re: Tank rust woes
« Reply #1 on: September 30, 2014, 05:13:56 AM »
Sounds like you may be to that point. I have had luck with them not rusting again, maybe you did not get it all out last time and like a cancer it has come back. Just remember with each major rusting and rescue cycle the metal is getting thinner.
  I have a liner product I like when all else fails and sure others will chime in with their recommendations also.

Offline calj737

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Re: Tank rust woes
« Reply #2 on: September 30, 2014, 05:25:13 AM »
De-rust and install a Caswell brand liner. Over and done.
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Offline iron_worker

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Re: Tank rust woes
« Reply #3 on: September 30, 2014, 07:50:44 AM »
If you keep your tank topped up all the time it shouldn't be able to rust much.

IW

Offline xtravbx

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Re: Tank rust woes
« Reply #4 on: September 30, 2014, 08:06:34 AM »
Muriatic acid to eat rust.

Red-kote to stop it from coming back (or keep your tank topped off as suggested).

Also, after the muriatic acid bath you could let the tank soak in a phosphoric acid bath. That provides a coating on the metal close to the original factory coat.

Offline BeSeeingYou

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Re: Tank rust woes
« Reply #5 on: September 30, 2014, 08:41:16 PM »
You have to neutralize the acid with a baking soda/water rinse otherwise it will flash rust no matter how much you rinse it.  Phosphoric acid is the only one you do not neutralize with baking soda/water rinse as it leaves a protective coating.  Be careful with Muratic acid as it is aggressive and the fumes are very nasty.  It is quick and effective but if you are not in a hurry use something easier to deal with.  If you go with muratic acid and then a phosphoric acid you still have to neutralize the muratic acid.

Offline grcamna2

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Re: Tank rust woes
« Reply #6 on: September 30, 2014, 09:15:06 PM »
I think the only way to keep that rust(iron oxide) from continuing to return is to finally give it a decent liner.
Make sure that tank is 100% BONE DRY before you install the liner after all the prep work.The man who used to do all my motorcycle repair  tanks when I did this full time would stick a high-volume,low pressure air hose inside the tanks and switch the hose from one side to the other for days literally... before he would pour the liner into it and finish the sealing process.He told me "if you don't get ALL the wet moisture out of Every crevice inside those tanks,that's just where it'll begin to lift away from the tank,in those areas". He did tanks for me for a few years until his boss told me and the other M/C shop on the island "he won't be doing Any more motorcycle tanks" & that was his final word. Al was suffering from all that MEK that he had to use to thin out the RedKote.
I was really bumming out because I don't like doing them.  ::)
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Offline mrbreeze

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Re: Tank rust woes
« Reply #7 on: September 30, 2014, 10:44:34 PM »
I finally got around to doing the  original tank that came with my bike in 2000. The rust was bad and I wasn't sure if it would come through without getting pin holes but it was fine. I was gonna use muratic because I already had a gallon but decided it may be too strong after reading some of the comments here. I ended up starting with white vinegar and although it was working (slowly) I decided to bite the bullet and try the Prep & Etch method which was available at Home Depot for $16-17 per gallon. It worked great and left behind the coating to keep the flash rust at bay. You have to shake the tank every so often as it sits in the tank. After 1 day it looked good but you have to flush real good with water and then dry the water out. I used compressed air and then poured a pint of rubbing alcohol in and shook it up. Then hit again with the air. It came out great. Then you can just fill with gas and go or what I did was put some ATF in and swish around because I am storing the tank. The Prep & Etch doesn't have instructions for doing the inside of a tank but it works good. It is now 3 months since I did this and it still looks fine although I have decided to sell the tank instead of storing it.
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Offline Duanob

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Re: Tank rust woes
« Reply #8 on: October 01, 2014, 10:30:10 AM »
De-rust and install a Caswell brand liner. Over and done.

I used to think so but I'm pulling my recomendation of Caswell's. I did everything by the book meticulaously and still had a leak. I even did a double layer as recommended by Caswell in the area with the pinholes. I won't waste my time and money on them again.

FWIW I wouldn't line any tank that doesn't have leaks. If it's just rust, get rid of it by many various methods as stated on the board (the Prep-n-Etch is my choice) and pour a quart of Marvel's Mystery oil right after derusting and swish it around if the tank is going to sit. Drain every drop fo fuel out of the tank and carb bowls when storing the bike for winter.

If you leave a tank half full, water will form when the air space condenses on the inside of the tank. Ethanol gas makes this even worse. That's where your rust is coming from. If the tank is stored either 100% full or bone dry with a thin film of oil, no condensation, no problem. But if you store it full don't let it sit too long without marine Stabil or similar, especially enthanol fuel.
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Offline calj737

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Re: Tank rust woes
« Reply #9 on: October 01, 2014, 11:31:14 AM »
With all due respect, Duanob, either they weren't pinholes (exactly how small if a pinhole anyway) or you didn't do it "by the book". I appreciate that you had an unsuccessful experience and may be dissuaded from using their product, by you seem to be an outlier in terms of success and satisfaction with their product. Doesn't mean you're wrong, just an unusal negative result.

You are correct about the fuel level causing/promoting rust. But, it's probably easiest to line it (in my opinion) once he's had repeated problems.

Most difficult part of "following the directions" is there's often no way to be 100% certain you've removed all rust, moisture, gotten perfect adhesion, full coverage, etc. it's all about diligence and effort. But still may have to repeat it due to small errors or insuffcient coverage.
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Offline Duanob

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Re: Tank rust woes
« Reply #10 on: October 01, 2014, 01:42:50 PM »
I would tend to disagree with you as I was there.  A pin hole is a pin hole what more explanation do you need? I had a few pin holes in a certain area but the size were all the sixe of a "pin". I spent 3 days prepping the tank. I even made sure the ambient air was ~ 70 degrees F and the tank was warmed up as well. I followed the directions to "T".

Most difficult part of "following the directions" is there's often no way to be 100% certain you've removed all rust, moisture, gotten perfect adhesion, full coverage, etc. it's all about diligence and effort. But still may have to repeat it due to small errors or insuffcient coverage.

Isn't that Caswell's claim to fame? Not that there was anything inside my tank but that's was Caswell claims is you can line over old liners, rust, etc. I was just like you as far as recommending Caswell but after a failure I pull my recommendation, that's all.
If you read lot's of reviews, which I have read plenty, there are absolutely NO tank liners that get much more than an average rating. Not on the Honda, harley, Ducati, BMW, DoTheTon or any other boards.

Edited to add: Also I let the tank liner sit for 4 weeks before putting any gas in it. After that I put pure gas in. I didn't put any ethanol gas the in that bike just in case it reacted with the liner material. In the end it didn't work.
« Last Edit: October 01, 2014, 01:52:30 PM by Duanob »
"Just because you flush a boatload of money down the toilet, doesn't make the toilet worth more",  My Stepfather the Unknown Poet

1974 CB360T
1976 CB550K2 Resurrected
1976 CB550F2 Barn Find
1979 CX500 VG "HONDA-GUZZI"
2007 Moto Guzzi Breva 750ie
2015 BMW F700GS
Another 1976 CB550K Cafe?

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Offline alacrity

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Tank rust woes
« Reply #11 on: October 08, 2014, 08:40:52 AM »
I have no experience with caswells liner and leaky tanks. I have however done three rusty tanks with Caswells and now swear by it.  It takes good prep -phosphoric acid roofing nails and drywall screws (10 each counted on the way in and on the way out- didn't wanna leave one in there by mistake) and patience.  Once the tank is clean and dry (yes really dry --like 0% humidity -- the caswells worked perfectly.  All three tanks have been in service for more than a year now.  My buddy uses redkote and has good results too .  I have heard of people have problems with por15 and kreem.  My two cents


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