Motorcycle Forum banner

How to clean a gas tank thats been sitting?

183K views 25 replies 23 participants last post by  pagnaeli 
#1 · (Edited by Moderator)
As the title states the bikes have been sitting for a few years, what does cleaning it entail?
 
#2 ·
First, check for rust with a light and a small mirror. If no rust, add a fuel system cleaner, like Seafoam, and slosh it about, let it soak. Drain it through the petcock, and see how stained it is. If its not too bad, just use the cleaner at the strong mix recommended, like 2oz per gallon of Seafom, with fresh gas. Repeat for a few tanks.
 
#5 ·
I have done this before. If there is rust I rolled BB's for a couple of weeks taking them out every day. Repeating the process many times, they help to break up the rust. Then get some products that clean the inside. They also sell stuff that then seals the inside of the tank to prevent the rust from coming back. I did this over 15 yrs ago and it still runs with no rust. That being said there might be something newer out there, but old technology works just as good sometimes.
 
#7 ·
Sorry to butt in, but do you think using vinegar is a good idea? Looked online and some people said it works, but just have to rinse it off with a bath of baking soda and water afterwards to prevent it from eating it more. Also gravel for fish tanks? Mine is gunk up in rust and smells of varnish that could be smelled 10 ft away from it.
 
#8 ·
My rust is mild. After my tank sitting all winter I emptied the fuel and noticed a slight discoloration. To avoid I'm about to try vinegar in my tank.

Going to fill it entirely with a mug full of small gravel. Shake it around until my arms hurt and then let it sit 24 hours.

Then ill dump it and fill it with a water and baking soda solution and let that sit for 20 minutes.

Then ill rinse throughly and let dry in the sun.

Anyone think this a bad idea? Is white vinegar effective enough? Anyone know if I should rinse with dawn/water first?
 
#11 ·
mine was rusted.. i dumped out a couple pounds of rust flakes. Poured on a 2 liter of coke.. yeah coke. sloshed it around.. let it sit in the sun for 24 hours.. then dumped it out. then rinsed with water several times. used a pressure sprayer severl times, dumped, rinsed, etc..

it has been sitting for 2 weeks drying in the garage.. then i will use POR-15 to coat the inside.

the main problem, i cant figure out how to get the petcock off the tank.. the bottom of it has a bolt head, but that unscrews the bottom of it where a filter is sitting. and there is no bolt bolting it to the tank.. lol
 
#13 ·
Just finished getting the rust out of a tank off a CL175K4 and I thought I'd share the results:

Tank condition - inside: very rusty. Could hear flakes of rust rolling around. Turn it over and you got a small pile of rust.

Tools needed: pressure washer, heat gun

Supplies needed: random nuts and bolts, a gallon of CLR.

Method:
1 - Shake out loose rust bits.
2 - Plug all the holes on the bottom.
3 - Pour in the CLR.
4 - Put the gas cap on.
5 - Change tank position about every 2 hours so the CLR has opportunity to interact with 100% of the inside surface.
6 - Keep this up for about 18 to 24 hours.
7 - Pour out the CLR and all the loose gunk.
8 - Open the holes you plugged in Step 2. Open any other holes there are.
9 - Pressure wash the inside.
==At this point you'll be tempted to say you're done, but you're not. The pressure washing really cleans the surfaces it initially blasts, but softened rust remains on the surfaces it can't get to. You can verify this by running your finger on a surface the blast didn't get to. The fix is to:
10 - Dump in the nuts and bolts, put the cap back on and shake.
11 - Shake for a few minutes, then dump out the nuts and bolts.
12 - Pressure wash the inside again.
13 - Verify if rust is still present.
14 - If rust is still there, repeat 10 - 13 until you're happy.
15 - Dry the inside immediately using a heat gun, use caution not to burn yourself or the paint.
16 - Plug all the holes at the bottom again and pour in a splash of 2-stroke gas. Put the cap on and roll the fuel around to coat all inside surfaces.

Total time: 19 to 25 hours
Total hands-on time: 1.5 hours
total cost: $25 (for 1 gal. of CLR)
 
#18 ·
I've done sealer in tanks, both had it screw up. One the stuff turned to goo when gas blends got certain additives put in, the other didn't stick and it rusted again under the coating.

Then I went to a radiator/fuel tank repair shop that did trucks, cars, etc. Cost me under $50 to have a leak soldered, the tank cleaned, and Red Kote hard shell coating liner done on it. Now I will let the pros do the work. Less headache and a better job. The shop where I used to work used to do Kreem, but went to the same radiator/fuel tank repair shop due to ease and the professional work done. They didn't do it on my suggestion, we both ended up there independently.
 
#21 ·
Tank electrolysis maybe the way to go. Its very cheap and cleans perfectly. You need a car battery charger for this (or any other high amp charger)

First you pour water in the tank and add alot of salt. Then put a metal rod in the water inside the tank. The rod should not touch the tank on the inside or outside. You can use wood to hold the rod in place, without touching the tank. Then you connect the positive wire to the rod and the negative wire to the outside of the gastank. After 48 hours or so, it looks like you made tomato sauce inside of the tank, thats the rust that has been removed :D disconnect everything and rinse the tank with some gasoline.

There is a residue (black/grey, its called hematite) on the inside of the tank, you clean it by filling the tank with a slightly acidic liquid (even lemon juice works). After that you keep rinsing with water, until its clean.
 
#24 ·
I have seen so many opinions on this that I can only offer what I have learned by really thinking about the problem from a chemist's perspective..
For the best way to clean your tank,you really should know what kind of dirt is inside it. I have cleaned one automobile tank,one farm tractor tank, Two motorcycle tanks,and I have a PERFECT 35 year old tank from a CB500. It is really important what condition the tank is in before you start.
If your bike is a beater bike,with a rusty tank and you really do not care if it holes through after you clean it,by all means use whatever harsh chemical will do the job and the faster the better! If you want to use the most gentle method,I will describe it as going with electrolysis. If you have a nearly perfect tank with little rust and very nice paint,even electrolysis can ruin your efforts.
There are two kinds of problems. one is rust,and one is varnish. I usually go after the varnish first because varnish will coat the tank and the rust in the tank,making the rust more resistant to being removed by any method, electrolysis included
The cheapest way to remove varnish is with lacquer thinner. It simply dissolves the stuff into itself [dissolves into solution], and what does not completely dissolve turns into soft jelly. I get mine at a Sherwinn- Williams paint store for 15-20 bucks a gallon. Let the stuff set for several days,and it will not hurt the tank at all. Nice if you can afford enough to completely fill that tank.
Make sure that you save what comes out of the tank, because you can use it over again. I let all the gunk and rust settle and just draw off the clear [amber by now] liquid that comes to the top.
Electrolysis with laundry soda [not baking soda] as the electrolyte worked really well for me. It worked very well because I was working only on the rust and not a bunch of gasoline leftovers. Keep in mind to use a manual battery charger and a steel rebar works well to attract the rust,but when the reaction stops,you must clean the bar and just keep using the solution in the tank. Even when I covered the outside of the tank with heavy grease,the trail of foamy bubbles that came out of the tank washed the grease off and left a whitish stain behind, and that is what to watch out for. 5 thousand miles and three years later,no rust has returned. Note that I did use oxalic acid to convert the bare metal to a blue/black coating.
Now about my pride and joy Cb550 tank that has darn near perfect factory original paint. I will use lacquer thinner first to clean what little gunk was left behind with gas and Stabil in the tank, in there 21 years, and perhaps a mild solution of toilet bowl cleaner [about one-10 ratio] to loosen the rust if any is present.No foam,no drama, filled to the top---just get it clean as possible without risking the paint. Many rinsings,dry it with shop vac exhaust, and then a treatment of oxalic acid that will convert what rust remains to an inert coating. Dry it again with the shop vac
There are postings, YouTube videos,and gobs of stuff about electrolosis that are available by searching the net. No need to repeat it here.
 
#26 ·
excellent info! I have agreed (granded I was a bit drunk at the time) to help a friend get her 1996 honda cb400sf back on the road after it has been standing still fro the last two years. Since I am not a mechanic it is a true stroke of luck to have found this forum. Excellent job! Thank you!

As soon as I can start a thread I will post pics of the whole process and hopefully in the right section.

I apologize if this is the wrong section or if I am off topic, I just got excited with the plethora and mass of info available here!!!!

Thank you!,

Harris
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top