How to remove bad RUST and coat the inside of a Diesel fuel tank on a Case 310f Dozer

[DIEBOG]

So the problem I have is this rusted fuel tank on my dozer. There are large chunks and a build up on the bottom, but the tank doesn't leak. I was thinking about getting some of that tank coating stuff, but the tank is part of the seat and is fairly large as it houses the batteries as well so I don't know if that would work or even be possible to jostle it around enough to properly dislodge and clean out the rust as well as be able to uniformly apply the product to the inside. I took off the cap/bowl on the bottom that catches junk (held on by 4 9/16 bolts) and used a pressure washer to blow out everything that was loose until water was clear and no more chunks came out, but after I did that I reached in the hole with my finger and can still feel allot of caked up rust on the bottom. Now when looking down the fill hole, the sides are not rusty at all, but if you are familiar with this model, the back of the tank slants forward and under the seat which creates the bottom of the seat area. So its is impossible to see down to the very bottom and you can forget about getting any kind of tool in there to scrape it down or even vacuum it out. Oh and I did spray the tank down with diesel fuel after I pressure washed it so it wouldn't rust.

I would really like to have the tank functional again so I don't have to rig a temp tiny fuel tank that could possibly leak and would get in the way. But I also don't want to mess with plugged fuel lines and fuel filters. Any sugg?...... Or has anyone encountered this and found a good way to at least get rid of the rust? After some research I found that some say apple cider vinegar will eat rust, or plain vinegar, some say a type of acid (don't recall the type) one guy had used electrolysis and rebar which takes the rust and basically plates it to the rebar. There is a product called naval jelly, but it comes in small bottles and costs allot. I'm sure there are many more ways, but I don't really want to experiment with it and waste allot of time. I have tried soaking rusty bolts that just had light surface rust in apple cider vinegar, as well as white vinegar,but the results wern't the best and that was just light surface rust. I want something I can dump in there, let soak for however long, and have a perfectly clean "rust free" tank that I can use without worrying about fuel issues and such.

 

[willie59]

Granted, someone may come along and squash me like a possum on the centerline, but rust is caused by the reaction of iron and oxygen in the presence or water or moisture in the air. In the case of your fuel tank, it's because your tank has been exposed by excessive water in the bottom of the tank for an extended period. Once rust starts to grow on iron, very little you can do to "sanitize" the steel of the bottom of the tank. There may be some type of coating out there that is compatible with fuel, but I'm not aware of it. Aside from that, about the best you can do is remove the rust scale, banging on the steel with a hammer to loosen the scale and wash it out. Once you have scale removed, keep tank full of fuel to control water in form of condensation and maintain a regiment of keeping water drained from bottom of fuel tank. You should be good if you do this.

 

[DIEBOG]

Thanks for the fast response!, Ya there are a number of products out there, but are made more for the small dirt bike or atv gas tank. You have to be ale to spin it all around to evenly coat the inside. I never thought of using a hammer to dislodge the junk, but how does one flush it out after its dislodged? I tried using a piece of hose attached to a vacuum, but it so tough ti get to the bottom of this tank. Worst case I could always take the tank off, plasma cut the bottom out, then I will be able to throughly clean it out and weld in a new bottom. But hats a hell of allot of work. Plus if you have the tinyest pinhole, it will need to be taken back off and welded up. Not fun

 

[Birken Vogt]

I am not sure how big and heavy this tank really is, but the rust does not really need to be sanitized, it just needs to be de-scaled really well. Once it is full of diesel and not water, there will be no further rusting. This is why they say to keep tanks full, to keep the water condensing surfaces to a minimum.

My favorite way to accomplish this is to fill a tank with sharp edged gravel, nuts and bolts, etc. and some sort of fluid (grit hand cleaner has proven useful, also diesel and/or gas) and then shake and/or rotisserie it for a long time. Then of course you have to wash the dickens out of it to get the grit out. But this will get it clean, and you can put it back in service with no worries.

Also check out bore scopes, I hear they can be pretty cheap these days and all you would need is a low grade one for this job.

 

[DIEBOG]

So with a tank this size, what do you recommend to shake and rotisserie the tank for an extended period of time? Something mechanical, or just by physically holding the tank and manually doing it.


Here is a pic of what the tank looks like. This isnt mine, but the tank looks the same

 

[boaterri]

There is a product called POR-15 that makes an excellent fuel tank repair package.

Rick

 

[dirtdobber1]

Hey Diebog,

I personally like your worst case scenario mentioned above - cut the bottom out of the tank. However, I would cut around the sides of the tank close to the bottom, within a few inches or so. Although you will have to get a leak proof weld, that shouldn't be a problem if you clean the weld area very well, inside and out. If you're using a gas shielded weld, stay out of the wind! If the thickness of the tank material is a concern when welding it back together, tack a piece of flat material to the inside of the tank to form a backing strip. It doesn't have to be heavy stuff. Once you get it all welded back up, seal the fittings enough to put a little air pressure on it and apply soapy water to the weld. Leaks will bubble.

While this is a lot of work, it is perhaps the best and most reliable way to get your tank clean. You will potentially spend a lot of time on these other methods, particularly figuring a way to shake and roll the tank continuously with the gravel trick. Then, if your tank is rusty enough, you may find pinholes due to the rust. That would be a bummer.

And finally, just because a fuel tank has no fuel in it doesn't mean it is not a danger. Diesel fumes will blow, so remove the oxygen from the tank before you start cutting on it or introduce any spark or flame. You remove the oxygen by filling it with something other than oxygen such as argon - justs don't use anything that supports combustion.

good luck.

 

[Birken Vogt]

I'm not real big on cutting into a tank like this, especially this nice rusty one with lots of pockets to trap fuel. Even if it is inerted beforehand with gas, as soon as you fire up the torch or plasma cutter you are blowing lots of oxygen or air right back in there as soon as you start cutting. Maybe filling it with water, putting it upside down, and using a grinder would be a better option.

 

[Birken Vogt]

So with a tank this size, what do you recommend to shake and rotisserie the tank for an extended period of time? Something mechanical, or just by physically holding the tank and manually doing it.

One radiator shop here used to do car fuel tanks by strapping them to a rotating table that went about 10 RPM or less at around a 30 degree angle. I think it was adjustable, though. You'd want to try different settings and look with a mirror or bore scope or something.

I am imagining something that vibrates it real good like a paint mixer or sawzall would be even better but I think you would wind up burning the power source out before anything happened.

Doing it by hand is a last resort. You would probably get tired before it got nice and clean. But I have had good success doing smaller items by hand.

 

[Tennmogger]

There is a product called POR-15 that makes an excellent fuel tank repair package.

Rick

POR-15 makes a great line of products. I had a Unimog fuel tank that had been splattered by some corrosive stuff and had more than 50 pin holes, and some larger holes up to 1/4 inch after sand blasting. The POR-15 plugs the pinholes. The others were plugged with JB Weld. These holes were unique in that they started on the outside and worked inward, so sand blasting was easy. That repair was still good 12 years later when I replaced the tank with a new one (after an encounter with a rock made the tank non-repairable).

The POR-15 Metal Ready product will help clean out the rust enough to use the sealer.

Is there a way to cut a clean-out port in the top of the tank? If so, you could sand blast the bottom, then POR-15


Bob

 

[kenworth]

I had the same problem with the fuel tank on my gasoline powered fork lift. I took the tank out of the machine and tool it to my friends radiator shop and they cleaned it out. I'm not sure if they boiled it or just put some sort of solution in it and let it soak but it came out like brand new inside. I did not have it coated inside but should have had it done to prevent future problems. Now I drain the bottom of the tank regularly and use fuel stabilizer, 5 years later it still looks great inside.

 

[Birken Vogt]

I find it strange how sometimes there are problems with rust in fuel tanks, when most of the uncoated, bare metal ones I have looked into (infrequently) appear to have nothing but 100% crystal clean diesel with no evidence of anything settling on the bottom. It must be periods of non-use coupled with rain getting in, or bad fuel that does them in sometimes.

 

[RobVG]

I can't tell you how to use it but I've always wanted to try muriatic acid. It's about $8 a gallon at the big hardware stores

Found this thread on a model T forum.

 

[Jeembawb]

I can't tell you how to use it but I've always wanted to try muriatic acid. It's about $8 a gallon at the big hardware stores

Found this thread on a model T forum.

Interesting links there robvg

I don't think the muriatic acid (aka hydrochloric acid that leaves black oxides behind as a conversion coating) would be too good for the inside of a diesel tank. The other option in those links talks about phosphoric acid (aka coke and the more commonly available rust converter/metal preps), but this option leaves a zinc phosphate coating behind which may not be good in a diesel system - I am keen to hear if someone knows for sure if these residual coatings would be bad in diesel injection systems?

I have a small tank on my fiat 451c that needs something done to clean the inside out with and because it is small enough I am leaning towards filling it up with sharp bits and bobs and strapping it to the barrel on my cement mixer :Cowboy

Jimbob

 

[maddog]

plastic. That's the easy answer, but not practical if you're looking to stay with stock equipment. There are ways to prevent rust but that doesn't help much once the damage is done. There are sealants and such once the tank is COMPLETELY CLEAN. short of shaking it with nuts bolts or something that can bang the rust lose, cutting is probably the best solution

 

[maddog]

It's to bad someone hasn't come up with some sort of membrane that could fit inside of a tank????

 

[Karl Robbers]

I'm not real big on cutting into a tank like this, especially this nice rusty one with lots of pockets to trap fuel. Even if it is inerted beforehand with gas, as soon as you fire up the torch or plasma cutter you are blowing lots of oxygen or air right back in there as soon as you start cutting. Maybe filling it with water, putting it upside down, and using a grinder would be a better option.

No no no. Filling with water is the worst option of the lot. Diesel is not volatile like petrol and will present no hazard, particularly if a jigsaw or similar is used for the cutting, an angle grinder will be no problem either. In the case of a petrol tank all filling with water does is concentrate the fumes where they will still ignite in a spectacular fashion and the water is an electrocution hazard if using a grinder.
The absolute fail safe way is to get a steam pressure cleaner (hot wash) and tie the trigger on with the lance in the top of the tank and all other openings blocked. Leave the steam cleaner running until the tank is full of hot water and the tank itself is good and hot. This could well be 30 -45 minutes if not an hour. Shut off the steam cleaner, empty the water and work on the tank while its hot. If you smell fumes after emptying the water, give it another wash until there is no fume smell. Make sure that the hot water can reach all areas of the tank.
This really is not required for a diesel tank unless you wish to cut it with plasma or oxy acetylene.
How do I know? I do it for a living and have never had a tank emit so much as a puff, whether petrol, diesel or oil.
I think the best option for this tank will be to either replace the bottom of the tank or cut a suitably sized window and clean the tank via that and then weld the window back in.
Not a big fan of tank coatings - seen too many fail and peel requiring the tank to be cut open anyway.

 

[Delmer]

Karl, I'll have to disagree. From my experience and everything I've read, filling a tank with water and cutting it full is one of the safest ways to do it. And diesel or fuel oil most definitely WILL flare up, and possibly explode. Even if the tank seems clean, once the sparks hit any residue, it will get volatile.

If it was me, I'd add a larger tube from the tank directly to a bigger filter element, and then on to the regular pumps and filters, then throw some nuts in the tank and use it. Or use a temporary tank while you have the tank sealed up with nuts or gravel sloshing around in water for easier flushing. Only use an inch or two of fuel to get the most sloshing. The tanks I've seen are rusty looking, but the real problem is the fuel deposits that aren't affected by acids, heat, water, and maybe just a little by lye. Maybe water with gravel in addition to various chemicals is the way to go? Or burn the tank and scrub the ash out?

 

[Birken Vogt]

I have to cast a little suspicion on this one. Someone here once posted a nice manufacturer's sticker that said "buy clean fuel, keep it clean." I do not really trust filtration to clean up dirty or contaminated fuel. More like it is there to catch the odd particle or dirt that was introduced to the system. The problem is that filters are not 100% efficient at catching dirt and some may get through. This is not a big deal for fuel with the odd speck here and there because chances are the filter will catch it. But when the fuel is a muddy mess, then trash is going to be getting by left and right, to some degree at least. Whether this will be a problem for that old engine I can't say.

I do like the idea of using a temporary tank and having the regular tank full of abrasives at the same time.

Burning the tank will not affect the rust much.

 

[Delmer]

It's up to you to trust a filter or not. But if you hook up a 1/2" or bigger pipe to a big filter, it will be a lot less likely to plug and shut off, in the short term at least...

What I've seen in diesel tanks is not just rust, it's a rusty, gummy scale. I'm guessing it's caused more by bacteria, or at least "varnished" fuel, than by rust. Hence the burning idea. I've never seen one quite bad enough to try burning though.

edit to add: utube says that broken tempered glass is the best abrasive, break it in the biggest loader bucket you have, easier to gather up that way.