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Rust in Gas Tank.  What should I do?

3K views 19 replies 7 participants last post by  ducmeat 
#1 ·
No it's not my monster! Thank God!
I'm working on an old 71' CB175 Honda. It's got some rust in the tank and I was wondering what some of you gearheads would suggest short of cutting the tank in 1/2 and sand blasting it. I've heard there is some stuff on the market to get most of the flaking rust out and then another product that coats the inside of the tank. I know it's not a monster related topic but I'd appreciate any input on the matter. Thanks
 
#3 ·
Put a hand full of crushed stone in it along with a little water. Gently shake, slosh the stones back and forth while turning the tank every which way. Wash, rinse it out and fill with gas. Never let it get empty again. If its not rotten it should be fine. :) :)
 
#4 ·
Re: Rust in Gas Tank.

A buddy of mine, and myself have been working on a 75 honda 450... with the very similar problem. What you want to do, is make a solution of about 60% myriatic acid, and 40% water. You can get a gallon of myriatic acid from home depot or lowes for less than three dollars. Seal up all the holes in the tank, fill it up ALL THE WAY with the solution. Then leave it overnight. Dump it out in the morning, and do it again. This time for about six hours. Keep doing this until it starts draining clear. Then, use a heat gun to dry it out, and slosh it. This is the sealant you were talking about. It's kind of expensive, but you definately need to use it.

Another important little bit you should know... Don't let the tank sit for any amount of time without either the solution, or the slosh in it... as it will flash rust. And you wouldn't even believe how fast this can happen.

You may have to slosh it four or five times. You're going to want to put some in the tank, slosh it around, coat the whole inside of the tank, then dump out the excess.

Then do it again about five minutes later, and again, and again, and again. You can re-use the excess slosh, but after a little while, you're going to want to let it dry completely, and use some clean slosh. If the excess from this sloshing is clean, then your tank is sealed properly.
 
#5 ·
Re: Rust in Gas Tank.

Also, there are two kinds of sloshing solution. One is made for use with gasoline, the other is made to work with ethanol. The one that will work with alcohol is like, five times more expensive, and you probably don't really need it, unless you typically buy your gasoline with ethanol in it.
 
#7 ·
Re: Rust in Gas Tank.

Also, there are two kinds of sloshing solution. One is made for use with gasoline, the other is made to work with ethanol. The one that will work with alcohol is like, five times more expensive, and you probably don't really need it, unless you typically buy your gasoline with ethanol in it.
could you tell me what this sloshing solution is?
 
#10 ·
Re: Rust in Gas Tank.

Thanks so much guys you've been a huge help. I'll let you know how it goes.

Dents
 
#12 ·
Re: Rust in Gas Tank.

My husbands HD Fatboy is in the shop for that , the inside tank coating is pealing off and the tank is rusting.

They used a solvent to clean the tank and placed an in line fuel filter.
They are contacting HD to see if they will give us a replacement tank under warranty. The bike is a 1998. They have seen a "few" problems such as this so far.

HD replaced my engine casings on my 1996 Badboy when the cam went bad in 2002, this was a problem they were seeing a "few" of, also.
They say since we are the oringinal owners and bought the bike at this dealer and do all recommended maintenance, they some times will come thru with warranty things on the older bikes.
 
#13 ·
Re: Rust in Gas Tank.

I recently used KREEM fuel tank prep and liner kit on my rusty '96 M900 tank. My tank was severely rusted and it seemed to work well. Note-- the instructions said to leave the tank cleaner solution in overnight. I had to leave the solution in for several days to remove the rust. The tank is getting painted, so I haven't put fuel in it yet to verify the fix.
 
#14 ·
Re: Rust in Gas Tank.

DON'T USE KREEM!!!! You or the next owner of that tank will regret it. When it leaks or rusts next, it is almost impossible to get that stuff out. It becomes all gummy and........
 
#16 ·
I , too, have heard that Kreem is no good. Our HD shop sells it but does not recommend it??? ( go figure)

We are just useing the solvent cleaner and hoping that works, maybe getting a new tank from HD, if not and the old tank gives us more trouble we will replace it. Gives the hubby a reason to go with a "stretched" tank on his Fatboy.
 
#17 ·
Re: Rust in Gas Tank.

I just read through the entire POR-15 web site. How would you get the POR-15 sealer out of a tank if needed? I figure that a tank sealer is a "last resort". If it doesn't work your'e screwed anyway. I have not used the POR-15 sealer, but from the description it just seems to be a paint. The KREEM put a hard coating inside my tank. KREEM is said to fill small
seam cracks. I know people who have used KREEM and have had good luck. Since I'm a NEWBIE I don't mean to argue, but I don't see a big difference in the "after effects" in using either tank sealer.
 
#18 ·
Re: Rust in Gas Tank.

Kreem has been aroun for a long time. it always had the problem Norm refers to. i have no personal experience with POR 15 or Norm, but Norm has a sterling reputation with tank repair, and if Norm says use POR 15, that's more than good enough for me.
 
#19 ·
Re: Rust in Gas Tank.

The concern with any tank coating besides it's ability to plug leaks & prevent rust, is what happens it the tank has to be worked on again. POR-15 is a paint which can be coated over by simply etching the surface & then recoating. Kreem is thicker & never fully hardens. In time, Kreem almost always starts to come off somewhere. What you end up with are places where it has come off & is rusting, places where it is coming off & can be washed out with acetone, & places where it is still REALLY attached but won't accept an over coat because of the nature of Kreem. I've recoated 2 tanks that were previosly done with Kreem. Both took several gallons of acetone & days of rinsing & soaking before I could do any work, & one had rusted so badly along the bottom seams, that I had to reconstuct the panels.
My personal feeling on leaky tanks, is that it's best to weld, braze, or epoxy the leak & THEN treat the inside as a kind of safety net. I use the POR-15 sealer on every tank I repair for that very reason.
 
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