'74 70 tank repair opinions

[Jon Boy]

was riding the 70 at my buddy's over the weekend and things were good i guess (needs a new clutch). then i thought the motor was smoking at first then realized it was steam. wait steam? that's when i noticed it was spitting a small stream of gas onto the head and steaming off. needless to say i shut the motor off and coasted up to the garage threw my finger on it and waited, luckily no fire. after checking the tank out more there's a number of repairs on the inner bottom edges on both sides and what looks to be 2 layers of tank sealant. the top one is thin and kinda chincy IMO, but the bottom layer is a real thick rubbery type of coating. it seems to me the second coating didn't stick to the bottom rubber coating and is pulling up.

any ideas on if i should really try and save it or shelf it and just get a new one. also if i do get a new one are the "peanut" tanks the only chioce or is there a "hot dog" style like this one that i just haven't found yet?

camera was having a hard time focusing, but here's where it was leaking from and you can see the repairs.


the black wrinkley is the thin coating and the white is the good thick coating. notice the drip/nipple sticking up?


getting 3 home was fun. a pic after i unstrapped them. i was uncomfortable driving with the gate down.

[Stonewall]

I suggest cleaning it up real good, then patching it again with some JB Weld or JB Kwik. I have used that on gas tanks and other stuff before and it has held up real well, just make sure the surface is real clean or it won't stick good. Once it's dry, you can sand and paint it if you so desire.

[badass350x]

I suggest cleaning it up real good, then patching it again with some JB Weld or JB Kwik. I have used that on gas tanks and other stuff before and it has held up real well, just make sure the surface is real clean or it won't stick good. Once it's dry, you can sand and paint it if you so desire.

I agree on that too, clean the area really well with rubbing alcohol.

[250rRoostmaster]

I use KBS coatings on all my badly rusted tanks!! It a sealer kit that works amazing!! It's $40 shipped and you wont find a better product in my opinion!! I sealed a 200x tank 2 years ago and it still is holding up great!!!

[Jon Boy]

thanks for the info on the sealer, although i'm still wondering about getting the old sealer out of the tank. i'm thinking since the second sealer didn't adhere to the first from the way it looks, i figure it's probibly going to do the same again unless i can remove that bottom layer. it's a pretty thick rubber type of sealant. i'm planning on starting to clean it tonight. i noticed also that the fuel tube (long one inside of tank) is sealed up with the thick rubber sealant and it's only allowing gas through the reserve side, figure i'll just run a drill bit by hand through it.
i knew it was rough when i got it and i'm not complaining about this 70, it seems to be a good one. from what i can tell it just has it's normal faults and i've never had to do any work really to the others i have bought. it's no biggie to most, but this is the first one i bought that has needed work off the bat basicly. i usually only buy "used, but not abuse and well maintained machines".

[Jon Boy]

ok, got all the old JBweld off and scraped some paint. it's had some brazed areas and then the JB was basicly layed on top of that later on as it needed it. as you can see there is one big hole (pic1 came out with the JB) and another pinsize that the camera doesn't show by the front (pic2 shoots gas onto the motor) and a couple overshots so far after basic digging. there's a few more pinsized spots and a couple thin rusted areas that'll need attention as well. i would like to get it done right and have it brazed again, but that rubber sealant inside? it'll be fun, it's in there pretty good.

[swampthang]

So the previous repairs have only been on the outside of the tank? If thats the case I'd just braze up the holes on the outside and have the inside lined for extra precaution. If it has a liner inside thats peeling then IDK what you could do about that. I have never had any luck with using JB weld on a leaky tank IDK if im doing something wrong but I could only get it to hold fuel for about 2 weeks then gas would start to seep out the whole again. I have acouple tanks I'm going to look into having the insides lined. I talked to a guy at a radiator shop that said he coats gas tanks and has good luck with them. I dont have any holes yet but there pretty rusty. I'm not for sure a linning would seal up a whole that size of the one you have pictured by itself without patching the outside too.

[Jon Boy]

yeah, plan is to get the bad spots brazed then another good sealant for the inside. i got the thin chincy sealant layer out, but that thick rubber layer is stuck good. i just don't think it was rolled around good enough to coat the inside properly or else part has been burned out from previous brazing. i'm thinking the rubber layer needs to come out so it won't contaminate the brazing repair though.

[Jon Boy]

i've spent a few days looking for someone local to braze this 70 tank and i'm not having much luck. i figure if by next weekend i still can't find someone local then i might just buy a plastic aftermarket 70 tank for the short term till i get the origianl tank fixed. i do have one of those plastic/steel kits (high-end JBweld basicly) i've been thinking about using on the tank myself, but i'd much rather have it fixed properly.
anyone know if those plastic "peanut" tanks will swap/fit to my 74 with the "hot dog" tank? i really don't know, but it looks like the plastic tank might be too short for the 74 tank mounts and i don't want to order a tank unless i know it'll fit. then if i ever sell it the original and aftermarket tank will go with it. i don't plan on selling any of my 3wheelers anytime soon though, unless i find a deal on a good 250es or maybe 200x.

[Fungo Wizard]

Well, I am going to have to do the same thing to my 85 tank. I might buy a plastic tank, but in the end I want the original look. I thought it was in decent shape, then sanded bottom and pin hole started popping up.

[jays375]

There is alot of info on rusty tank repair here,do a search.Seems like every week somebody asks about rusty gas tanks or dirty carbs.

[Jon Boy]

yeah, i got all that stuff figured, just wondering about the fit of the aftermarket tanks or newer original ones now.

[KASEY]

I HAVE A TANK IF YOUR INTERESTED,, also sand blasting seems to work real good for finding thin spots I HAVE A perfect 85 70 tank that has 50 pinholes in the bottom!! its so nice i don't want to fix it and burn the paint! so i just look at it.....

[tblumer]

If the thick stuff is Kreem, acetone will take it off.

[Fungo Wizard]

I HAVE A TANK IF YOUR INTERESTED,, also sand blasting seems to work real good for finding thin spots I HAVE A perfect 85 70 tank that has 50 pinholes in the bottom!! its so nice i don't want to fix it and burn the paint! so i just look at it.....

Those pics aren't opening on my computer, but I was super excited cause mine is in good shape and I even filled it up with water to wash out some rust and it held fine. Then I sanded it on the bottom to make sure I could sand blast it and holes started opening everywhere.