How do I clean out previously sealed gas tank?

Hi Everyone,

I mentioned this back in Aug, I picked up a 1965 S90 and ever since have been trying to decide if I want to restore it or sell it to fund my other projects. Well, I told myself "I only want to get it running", but I think my resolve is slipping...

In any case, the PO (the original owner) put some kind of tank sealant in it about 15 years ago. It looks like it was originally yellow, but regardless is starting to peel off in sheets amongst all the rust and other particulates. Some areas it is adhering, but mostly comes off. The gas in the tank is circa 1995!

Any ideas on how to clean/dissolve this old mess out before I clean it properly?

Thanks!

George

 

I did one this summer that was coming off. I assume it was originally Kreem but it had yellowed. According to Kreem, acetone should dissolve it. I tried some samples in various concoctions and acetone didn't seem to touch it.

The best results I got were with lacquer thinner. It made the loose flaps a bit crumbly where shaking with gravel knocked them free. It took days of soak time to get that crumbly consistency. I can't say for sure that I ever got it all off, some more came out with the phosphoric acid rust removal.

At the end I decided that what remained could just be sealed behind the epoxy liner I used.

Good luck, I think you're in for a lot of work.

 

get another tank.

dave

 

Dont get another tank. Just go pick up a quart or two of acetone. Let it set on each side for a couple of hours. Swig around every once in awhile. Keep the tank closed so the fumes can do the work. If it is peeling, it is probably cheep tank liner like Kreem and it will come off easy with acetone. Just know that since someone has lined it before you will have to line it again. Otherwise it will keep rusting.

 

A new tank is not an option, thanks for the tip on acetone. I'll start with that and then follow up with electrolysis and then a phosphoric rinse.

George

 

With the acetone, you may want to throw in a chain or something along this lines that may help to crape off the old liner as you swish it around.

 

I highly suggest the stuff Fitz recommended for the phosphoric acid rinse. Klean Strip Phosphoric Prep & Etch. It says right on the label that it inhibits flash rusting (my guess is that when used on metal it creates a light black oxide coating which won't hurt a thing). I bought it at Home Depot. I used the whole gallon full strength and sloshed it around for about 15 minutes. then I filled the rest of the tank up with water and let it sit for an hour. Then drain and rinse, rinse, rinse with water. Final rinse with rubbing alcohol. Blow dry (I used a low powered heat gun and let the air escape through the petcock opening). Make sure the tank is dry, then coat the tank with about 5 oz of 2-stroke oil and a few oz of sea foam - slosh real good. Then I filled the tank with gas. (by the way 5 oz of two-stroke oil would give you about 87:1 mix ratio (if your tank is 3.4 gallons) which won't hurt a thing. Oh and get a #9.5 rubber stopper at Ace to plug the filler opening. Makes a nice tight seal for sloshing and makes the whole process a lot easier.