Topic: Advice on cleaning rusty tank..

[rosewood]

Ok I know this has probably been asked a hundred times but just looking for some advice on the best way about cleaning out an old rusty tank...I have some Evaporust to use but just want to know the best approach to get most of the flaky rusty debris out first..

I used some fuel so far about 1litre to slosh around a few times and draining each time which has helped get a bit out.

I plan to shake a piece of chain in there now and then repeat with the fuel..I have some 2.5mm guage chain just wondering whats an ideal length to use...1m , 2m, 3m etc...I only have 4m length of it.

I was thinking use the chain maybe with a bit of fuel..then rinse and flush out with water from a hose or water blaster and then some detergent before the Evaporust goes in?

The old fuel in there I think has left varnish layer on the surface of the metal also. Will the Evaporust still work if this is the case? how could I also get this varnish layer off before the Evaporust goes in?

Any advice appreciated...

thanks
rosewood..

[b1jackson]

Your chain treatment should tank the varnish off. Use whatever length works and can still be shaken around.

Your approach sounds like it will work well and the less you contaminate the evaporust with fuel the better as it can be reused many many times.

[Tom C]

I've had good luck using a couple of handfuls of drywall screws inside the tank to knock off flakes of rust and old coatings.  And I've used denatured alcohol rather than gas simply because it's less stinky and easier to dispose of afterwards as it evaporates faster than gasoline. 

[rosewood]

Thanks for the feedback guys..

I ended up shaking the whole length of chain in there (tied a piece of string to the center and let it hang out through the cap so i could pull out easily) dropped half the length of chain on each side of the tank) shook for a few minutes and then rinsed with a couple of cups of what we call in new zealand methylated spirits which I think is basically denatured alcohol...this definitely helped get more out and helped brake down the existing sticky residue a little more. I then blew it out with the vacuum cleaner on reverse to dry out. Put the chain back in with a couple of cups of evaporust agitated again and let it sit overnight. I plan to keep agitating it today to help attack the bulk of the rust at the bottom before i rinse and blast out with water and detergent. 

Maybe do another rinse and dry with the alcohol first before I completely fill with evaporust...will post some pics if it works out ok..

[rosewood]

A bit of an update on this if anyone is interested...

My initial treatment on the base with evaporust worked well and it did a great job after a few days..I used some more denatured alcohol to rinse out again all the crap after getting rid of the evaporust. followed by a thorough flush with a water blaster and then just the hose. added some detergent and good shake before the flushing with a hose once again. Another blow dry with the vacuum cleaner and then i filled the tank with the rest of the evaporust I had left. unfortunately I was short by a few litres to completely fill it.

I let that sit for a good few days shaking multiple times a day with the chain still in. after 4-5 days i then drained and inspected....it looked really good but still surface rust above the level of the evaporust.

I used a rubber glove over the filler cap screwed back on and turned the tank over upside down and filled again with the evapo roughly half fill. figured this would be enough to get to the top of the tank. It leaked through the cap breather a bit still but only slowly. I just kept a bucket under it and refilled the tank with it each day.

left it like this for a few more days shaking daily. when i did drain and inspect unfortunately surface rust had already started forming on the bottom again. it must have been condensing inside while upside down and shaking the tank to coat all the inside mustn't have been enough to stop the flashing on the already cleaned surface.

I bit the bullet and brought more evaporust this time enough to fill the tank completely the right way up.  its been like this for a few days again and i plan to do the same upside down trick again but only for a few hours this time to get to any air pockets around the tank lid recess (cb550f tank).

Hopefully this works and i have a completely got all the rust this time before rinsing with alcohol and coating with wd40 or a oil/fuel mix.

rosewood.. 

[IrocRuss]

I just finished de-rusting my tank.  Investigated several options and was thinking about the Evaporust, but I decide to try Electrolysis because it had similar results to other chemical cleaning, but cost almost nothing.  All you need is a 2-6 amp battery charger, Arm & Hammer Super Washing Soda Laundry booster Sodium Carbonate (not Baking Soda, Sodium Bicarbonate) and distilled water.  The process before and after are probably the same as using the Evaporust.  My tank didn't have any varnish in it, so I just used some nuts with water and shake. Put the water and sodium carbonate in to form an electrolyte, and an anode in tank opening.  I was debating on writing up what I did, if there's any interest I can with more details.  After the process is done, 2-3 days, I follow up with high pressure water rinse, bolts back in with water and shake, to remove the black material left from the process.  Rinse again with water until clear.  I tried using Heet since I got it free from neighbor, but it wasn't drying out even though I was using a heat gun to blow into tank and heat the outside.  I ended up using denatured Alcohol (already had on hand) to absorb and used the heat gun, this dried everything out nicely.  I first tried spraying Marine fogging oil in tank, but it doesn't really fog enough to get good coverage.  I ended up mixing Stable and Marvel Mystery oil and shaking it around.  That didn't get total coverage so I added a little gas to thin the viscosity and that did the trick.  A couple of important notes especially with certain chemical treatments, remove aluminum petcock and make a gasketed blind plate to cover holes.  Also you can buy a plumbers test plug made for pressure testing PVC vents that are normally open to atmosphere.  I'm including a couple of pictures.

[jaytee-nz]

Rosewood - if you want a cheap tank liner put PA10 primer paint in the tank when you have finished derusting it.
I've used it in two tanks and the fuel does not affect it all.
You don't need a lot - just keep swirling it around in the tank to coat everywhere and tip the excess out to allow it to dry (can take a few days to completely dry though)
About $35 at Mitre 10 for 500ml which will do several tanks.
Cheers - JT

[rosewood]

Thanks guy for the tips..

IrocRuss I had a quick look into electrolysis but decided the evapo as it looked like people got good results from it, maybe next time ill consider it more. hopefully there wont be a next time though...its all quite a tedious process..

Jaytee I really want to avoid a liner. The tank that came with my bike the PO lined. Rust was still falling out and I was at a loss as to what to do with it. Thankfully I got lucky finding another...as you know parts like this are pretty non existent in NZ. So if i can sort this one and keep it in good condition with out liner that's my preferred option.     

[Bodi]

No need for a liner if the tank isn't badly rusted to where there are or may soon be pinholes.
I've seen too many tanks with liners peeling or turning to goo. Long before ethanol could be blamed.

If you can afford evaporust it does an excellent job.
Be extremely careful using a vacuum to dry a tank. Not a problem with water but gasoline... never. Vacuum fans almost all use brush motors that continuously make sparks - the vacuumed airflow goes through the motor to cool it. Boom. Using one on blow (not suck) is fine and dries as well as or better than when sucking.

I second the warning that washing soda is a relatively strong alkali that will corrode aluminum agressively, but not bother steel. Hot soak tanks meant for degreasing iron engine blocks use strong alkali chemicals, and can eat away most of an aluminum block surprisingly fast. They are not common now since most car engines are aluminum but in the 70s it wasn't rare for someone rebuilding a bike engine to destroy theid cases by trying a hot tank at the local engjne shop to clean them.

[Kcanela]

I’m also getting ready to tackle this project this weekend, my approach is vinegar and self tappers ( a whole 50 pack) and just swishing then around for intervals through out the day and letting it soak over night, hopefully this works

[Spanner 1]

The tank on my K1 750  ( gold bike ) was super rusty when I got the bike but I was determined to save it as it was original to the bike.  I used a toilet bowl cleaner, don't remember the name, and a bunch of drywall screws and shook the sh#t out of the tank as long as I could  over 3 days. Then I put it back on the bike. I knew there was loose rust in the tank migrating towards the petcock so I zip tied a bar magnet to a piece of clothes hanger wire and 'fished' it into the tank with a flashlight right beside the petcock. I made a loop on the end with it being just long enough to sit under the fill cap. I would take the magnet out every day and wipe the rust particles off it and fish it back beside the petcock. Over a few days the rust got less and less. That tank is still in use on the bike 10 years later !

[rosewood]

common motor did a video just recently on this using vinegar..worth a watch..

[rosewood]

Bit of an update on this if anyone is interested. I finally got the tank sorted. It took me a couple of attempts to figure out I had to work very very fast to avoid flash rusting.

I filled the tank completely with Evaporust and let it sit for days and then over the last day kept rotating it upside down and right way up every few hours. I found that it condenses inside the tank if there are any air pockets and it will start flash rusting there. I used a little mirror to check under the filler cap area to make sure everything was clean.

Once I drained the evaporust I used a couple of cups of denatured alcohol sloshed it around and drained to help rinse the tank. My first attempt I did this around 4 times and then used a vacuum cleaner in reverse to blow out any remaining. I noticed the bottom seams of the tank inside still looked wet so I continued blowing until it all looked dry. In hindsight this extra time was enough for flash rusting to start. It probably wasn't too bad but I wanted it completely clean so I resorted to filling again and re starting the process. This time I only rinsed twice with the alcohol and worked alot quicker. I blew out again quickly with the vacuum cleaner but I wasn't that pedantic about getting it completely dry just enough for it to stop blowing out the mist of alcohol from the petcock opening. I then quickly bunged up petcock hole and poured about 330ml of wd40 in and sloshed around to make sure all surfaces were completely covered. 

Its been like this for a few days now and each time I check with a light and mirror everything looks clean inside still. I plan to just leave it like this until its time to use properly where I will rinse out the wd40 with fuel and then fill completely. Hopefully I've done enough now to have saved this tank and avoid using a liner.

rosewood..

[ekpent]

 Glad you did not jump right into using a liner. For me that's a last resort type of thing if they have a leak at a seam or pinhole. Sooner you get gas in it the better but sounds like the WD40 is holding the rust at bay.