Fuel tank rust dilemma

musigenesis

musigenesis

Senior Member
Joined
Jan 17, 2019
Posts
7,033
Location
Philadelphia
My fuel tank (and the frame supporting it) and the floor above are fairly rusted like the rest of my floor. Naturally, I can't access the underside of the floor in this area from outside because the tank is in the way.

I don't want to do anything as drastic as cutting the entire floor out above the tank, but what I am considering is cutting out the 8" or so flat strips of floor between each crossmember on the underside. Here's a pic of where I want to cut the floor:

fueltankfloor.png

With these openings cut out, I could access everywhere on the underside here and ospho and paint it and also deal with the top of the fuel tank itself. Then I would screw/bolt/plugweld a single large patch down over these openings (apparently there are weld-through seam sealers that I could use here, which I have to experiment with).

Is there an easier way to deal with this problem? How difficult is it to drop the fuel tank temporarily to allow easy access to the underside? I'd rather not cut these additional holes in the floor if I don't have to.

Is there anything to worry about during the demo as far as the fuel tank itself is concerned? Like, any wires or something I'm likely to cut through?
 
brokedown said:
if you think Ospho is enough to fix it, i've had good luck with spraying it. You can get one of those pump up sprayer kits from Home Depot and cover the top of the tank through that existing hole.

Something like this.

https://www.homedepot.com/p/HDX-1-Gal-Pump-Sprayer-1501HDXA/307766754

Painting it could be more of a challenge since spray cans tend to only work upright...
Click to expand...

It would be kind of tough just getting coverage with the ospho. The whole underside here (and the tank) was originally covered with an undercoating which is now flaking off in a lot of places. Reaching through the hole I might be able to douse the top of the tank but not the underside of the rest of the floor above the tank.
 
if the tank is empty you could drop it, the fuel lines should all be hard metal coming in and removable with a wrench.There are different setups for filler pipes, I've seen some metal attached to rubber attached to metal and I've see just straight metal. It's not unheard of although I haven't done it personally. A floor jack would make the lifting up and down part easy.

I have an aversion to cutting holes in my bus and would try just about any other option first.
 
Heh, holes in my floor don't really bother me for some reason. :dance:

My tank is about 3/4 full right now, unfortunately.
 
Sounds like you need to drive bit to burn off that excess fuel. See you at the Skoolie Swarm?

I just re-mounted my diesel heater yesterday which involved a reciprocating saw with a metal blade cutting through our finished floor and metal floor pan. It's still fresh in my mind, I hated it! Worst thus far has to be the 4 inch hole saw I used to run my shower drain.
 
Eastwood makes a product called "chassis saver". They also make a spray-wand setup for it worth your checking out. Some of the IHC folks like it more than por-15.

Cutting up your floor has an element of risk unless you can see that no fuel lines are running close to where you might cut...

Best way would be to drop the tank. A transmission jack will handle the bulky object better... At 7lbs/gallon you'll wanna transfer most of that fuel...
The 33gal tank in my Scout weighs 80lbs empty -- it's difficult for me to wrestle with by myself but I managed.

I assume your tank is inside a cage like mine (dot safety reg for school buses).
Is your cage bolted to the frame or welded? Maybe lower them both together with four screw jacks on the corners of the cage?

You will need to remove the flaky undercoat/paint to properly treat surface rust and repaint.
 
Tanks aren't hard to drop out, after a good clean out I had mine sandblasted and powder coated so I wouldn't have to ever worry about it again. There were a couple rust spots where the strap meets the tank so I patched them before sandblasting.
 
I tried a oil paint additive called Owatrol Oil on a rusty truck frame. I mixed it with equipment paint which is pretty tough by itself. I was impressed with the results to give the truck a few more years.
https://www.owatrolusa.com/product/owatrol-oil/
If I couldn’t drop the fuel tank I would treat it several times with Ospho then paint it with Owatrol/equipment paint. Then pray.
 
musigenesis said:
My fuel tank (and the frame supporting it) and the floor above are fairly rusted like the rest of my floor. Naturally, I can't access the underside of the floor in this area from outside because the tank is in the way.

I don't want to do anything as drastic as cutting the entire floor out above the tank, but what I am considering is cutting out the 8" or so flat strips of floor between each crossmember on the underside. Here's a pic of where I want to cut the floor:

View attachment 41237

With these openings cut out, I could access everywhere on the underside here and ospho and paint it and also deal with the top of the fuel tank itself. Then I would screw/bolt/plugweld a single large patch down over these openings (apparently there are weld-through seam sealers that I could use here, which I have to experiment with).

Is there an easier way to deal with this problem? How difficult is it to drop the fuel tank temporarily to allow easy access to the underside? I'd rather not cut these additional holes in the floor if I don't have to.

Is there anything to worry about during the demo as far as the fuel tank itself is concerned? Like, any wires or something I'm likely to cut through?
Click to expand...




If you have/rent/borrow an inspection camera, shove it in the hole and check it out. Ypu may be ok since the gas tank is shielding it.
 
When I bought my bus, one of the things wrong with it was tank starting to leak. I think it is rust and wear from the straps. I was going to drop it, so this thread may be helpful. It isn't a very bad leak, but it's on the todo list to fix.
 
I think I'd be inclined to agree w/ the others suggesting pulling the tank. At least trying to. It sounds like one of those jobs where trying to find work your way around something you hope to avoid (aka pulling the tank) ends up being more of a pain than if you had just dealt with it up front. Be the best way to ascertain the condition of the tank & deal with it as well, if necessary.
 
TheHubbardBus said:
I think I'd be inclined to agree w/ the others suggesting pulling the tank. At least trying to. It sounds like one of those jobs where trying to find work your way around something you hope to avoid (aka pulling the tank) ends up being more of a pain than if you had just dealt with it up front. Be the best way to ascertain the condition of the tank & deal with it as well, if necessary.
Click to expand...

Yup...
Reminding me that one of my tank straps is broken -- since it's supported by the cage I haven't worried about it but that amount of weight left to rub just a little bit could cause an issue...

Anytime I'm on the fence about investigating the condition of a part I'd rather not bother with I ask myself; if this was one of my assigned aircraft would I be hesitating, or recommending "deferred maintenance", or tearing it apart...?
 
Unfortunately I lack the experience, tools and a place where I could drop the tank. Even if I could pay some place to do it, they wouldn't then let me spend a few days treating and painting the underside there before putting it back up.

I took a peek in the access hole today, and there's like an inch thick layer of debris on top of the tank, and a few of the loose seat brackets. I wouldn't be surprised to find some of my missing tools down there. Surgery is tomorrow morning.
 
musigenesis said:
Unfortunately I lack the experience, tools and a place where I could drop the tank. Even if I could pay some place to do it, they wouldn't then let me spend a few days treating and painting the underside there before putting it back up.

I took a peek in the access hole today, and there's like an inch thick layer of debris on top of the tank, and a few of the loose seat brackets. I wouldn't be surprised to find some of my missing tools down there. Surgery is tomorrow morning.
Click to expand...


Are you fire proof?
 
musigenesis said:
I don't think so. I set fire to my lawn a few weeks ago when my leg was on it, and it hurt.

Why do you ask? I'm not planning on cutting my floor with an acetylene torch or anything.
Click to expand...




Cut off wheels throw sparks and hot slag. While I know diesel is not flammable like gasoline, it would still bother me to have sparks around it.

I've survived one explosion (natural gas)and set myself on fire twice (welding), enough to make me cautious. Walking thru fire is not much fun ether.


I'm thinking set some trash or oil on top of the tank on fire, then what?
 
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