black goo in the bottom of a diesel fuel tank

The CASE 400 diesel tractor has been sitting several years and several more before that. The bottom of the diesel fuel tank has a deep layer of sticky, rubbery, black goo. It is at the level of the top of the standpipe coming up from the valve.

Th fuel shutoff valve was clogged. I took it off and cleaned it. It flows very well now.

I want to clean the rest of this stuff off of the bottom of the fuel tank. Is there a solvent I can use to make this easy ? Brake cleaning spray did help soften it from the standpipe and fuel valve/petcock.

I've read steam or a high pressure spray can do it. The filler opening is only about 3". Not sure I can get all around in there.

I also read about some solvents that are said to help. I bought a gallon of each to try. Lacquer thinner, Zylene and denatured Alcohol(fuel). Also got a smaller container of Bio-Kleen for afterwards when I refill the tank with some fresh diesel.

My plan is to drain the tank and remove it. Remove the fill strainer, water trap and petcock. Then go to work on the 1-1/2" to 2" deep layer of black goo.

I realize I also may have some time to put in on the metal lines. So far I know the one from the shutoff valve to the 1st fuel filter is clear. The engine will start and run fine for 5-10 minutes. Then it dies. If I let it sit overnight it will do it again. Last time I did this, I unscrewed the 2nd filter drain tap soon after it died. It sucked air in. No fuel came out after the hissing stopped.

Any suggestions ?

Remove the tank scoop out what you can with what you can when try some gas to loosen up dump that then take a pressure washer to it. Thats what i would do if it was mine.

Clean all the fuel lines, filter heads and if it has a supply pump that too, first, then see how it does, injection pump may also have that sludge in it.

Removal of the tank will be needed to get a complete cleaning accomplished. E-85 will cut some of the muck, brake clean will work also. What may be the final step would be mechanical cleaning. Find an old motar/cement mixer. It must be one that the drum rotates. Plug the fuel line hole with the proper sized threaded plug. Use rachet straps to secure the tank to the mixer. Dump in 3 or 4 pounds of 16 penny nails. Put the cap on and turn on the mixer. I used nails because of the sharp points, also I just throw them away when done. A case 400 tank is big and wide open inside, use a mirror to periodically check the condition of the inside. I used a tank liner product on mine, mine came out shiny clean. BTW it had an inch of hard varnished up gasoline, but it was a 400 Case, so same as what your working with. Hope this helps. if you are close you could borrow my mixer. gobble

This black goo stuff is not solid. it flows but very slowly over a period of hours or overnight. Will gasoline actually dissolve it ? I'm surprised the diesel fuel doesn't seem to at all.

The CASE tractor manual says to use denatured Alcohol and Benzol to clean the bottom of the diesel fuel tank. Apparently Benzol is a name for something but that is where it gets confusing.

Benzol used to be a name for benzene and also a name for some kind of benzene mix stuff, mebbe a trade brand mix of benzene and toluene. I seem to remember that from a long time ago.

If lacquer thinner don't work, I wouldn't know what to say other than taking it to a shop and having it steam cleaned.

Yes Gas will help cut that stuff.

I have a sample of the goo stuff and was going to try each solvent out in small tests, tomorrow morning. I think I'll try the gasoline first since I have some on hand, not still sealed and returnable.

E-85

I had the same problem with old fuel. Solvents not going to help, regular gas no as well, the only thing I found that will cut the fuel varnish is E85. It worked so fast and easy I could not believe it. Paint thinners, gas, solvent, MEK, nothing cut that sticky goo better that E85. I keep some around now for cleaning carbs and such.

That BLACK GOOO is becoming a major problem and is in everything , it plugs up the fuel filters on the skid steer about every third tank of fuel , we are not getting the service life we use to on the fuel filters on the tractors and that Black GOO comes with each load of fuel we get hauled in .

I 3rd the E85. Worked super good on my Case 930 fuel tank.

(quoted from post at 16:44:49 10/14/19) I 3rd the E85. Worked super good on my Case 930 fuel tank.

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E85 will clean it up

OK the tank is off and it's far less goo than I thought. Just a thin layer. It is nowhere near as much as I thought there was going to be. It's not really hardened or rubbery as what I dug out of the shutoff valve.

I found some of that hardened rubbery deposit also inside the pipe to the 1st fuel filter. No more of it anywhere else I could find except I have not pulled the supply pump off to look inside it.

It sounded very gritty when I collected up a sample oft eh goo. I wiped the bottom of the fuel tank with a long flat screwdriver to reach in a get some. You can see a lot of detail in the photo of the cleaned off standpipe from inside. I'd say the layer is 1/16" or less.

I was mistaken when I was pushing the standpipe up into place and when taking it out. Apparently it has a rubber piece that seals around the standpipe.

I put a small piece of the rubber goo in some local pump gas with 10% alcohol. It started to get cloudy after several hours but not dark. Today I'll be testing each of the solvents I bought.

It took all day yesterday just to get the tank empty and off the tractor. The fuel that came out is definitely very old. Smells more like paint than it does diesel fuel. Lacquer brown color.

I took the 2nd filter canister down and the inside walls are very gritty feeling. Probably the same as the tank. A wire brush and Brake-Kleen got some off but I think it's good old fashioned rust underneath all the goo.

Whatever it is, it's tenacious ! I could not scrub a clean spot with the wire brush.

I started with dry, clean Olivio containers. My better half ... see loves her Olivio. I knew these would come in handy someday.

I pre-measured each solvent into it's own glass container and labelled the Olivio tubs. Left to right, gasoline, denatured alcohol, acetone, xylene, lacquer thinner.

I scraped up a big flat screwdriver blade full of of goo from the bottom of the tank. Then I managed to get 6 small stringy blobs off of it and into each plastic container. Did I mention this black goo is tenacious but it didn't want to stick to the bottom of the plastic Olivio tub.

Basically, as fast as I could get each jar emptied and and grab the camera, I took this shot. Less than 5 minutes. The acetone darkened as I poured it in.

After about 40 minutes I put an extra blob of black goo/tar into the ACETONE. A little while later I added some to the LACQUER THINNER. Then I added pieces of the papertowel I was using to wipe off the large flat screwdriver to the ALCOHOL, ACETONE and LACQUER THINNER.

The next day I saw a film being left by the LACQUER THINNER. No film depositing from the ACETONE. Neither solvent had dissolved all of the tar off of the paper towel but it's interesting to note, the LACQUER THINNER turned the paper towel darker.

The ALCOHOL seemed to be a distant 3rd behind (1) ACETONE and (2) LACQUER THINNER. GASOLINE and XYLENE barely did anything to dissolve the DIESEL tar in 24 hours of soaking.

I poured the rest of the gallon of LACQUER THINNER into the diesel fuel tank and let it sit overnight. I'll see what it looks like later today. Then, after draining it, I plan to do a rinse with the ACETONE and drain. To be followed up with a dilute solution of muriatic acid as needed.

I put the two blackened samples of thinner and acetone together and put the shutoff valve and a few other fittings into it. The stuff still wrinkled up the paint within minutes. It wire brushed off 100% with ease.

I noticed the water trap is cracked and has rubber plug inside that had become brittle and was falling apart. Do there water traps usually remain on the tank and get drained regularly ? Or is it supposed to be removable for service.

There seems to be some solder around the water trap flange that does not look as though the factory did it. The external water trap is centered at the rear of the tank bottom.

The fuel strainer that I took out of the filler opening on top could use some a new mesh. There are several pinholes and a few small tears in the mesh. Is there an easy solution for this ?

The tank is drying in the sun as I type. After the lacquer thinner soak, I rinsed it out with Acetone. Not too bad.

Some rust was apparent as sen in the photograph. I let it stew overnight with a couple of gallons of dilute solution of Muriatic acid in it. I also added a piece of chain and let it slide around inside for a while as I rocked it back and forth and rolled it around some.

It's been rinsed now and looks like i will need to do more if i want it to be pristine. For now I just want to use the 400 so I'm going to try the tank and see if it clogs the filters with rust or not.

Then I noticed the fuel tank filler cap has a vent. It was closed. I'm wondering if that is what was causing the engine to die out as a vacuum was created. I remember doing this years ago, too and now that I have rediscovered the vent, I think I need to label it so I don't forget again.



I had forgotten the vent is spring loaded and pulling it up and giving it a twist allows it to stay open

I'm going to leave the water trap non-functional for now also. It needs some work and I am not sure it's the stock one anyway. Looks like it was leaded into place instead of using two bolt holes that are visible inside.

I think it's supposed to be glass so you can see if there is water or sediment. I cannot find any references to the water trap for this tractor. Does anyone else have a functioning water trap ... water separator ... sediment bowl that mounts directly under the hole in the tank ?

This tank does not seem to have any provision for a pipe thread mounted water separator.




I'll be using a small hydraulic brkae cylinder seal on a long 5/16" bolts to seal it up. The rubber seal survived a couple of days in the lacquer thinner so I'm thinking it will be ok immersed in diesel fuel.

Before putting the tank back on, I set up a siphon to see if the injection system needed anymore work. Everything bled easily except the supply pump. Regardless, It started right up with 3 quick shots of starting fluid.

After several minutes of running, I wanted to see if I could observe fuel usage by watching the clear siphon hose. I stopped the engine so I could let air into the siphon to make the fuel level visible. The engine started right back up with no starting fluid.

I was hoping to see the level in the siphon tube go down as the engine was running. It did not move at all ! After a while the engine started to run erratically just as it had acted before all this work was done. I stopped it before it died.

I am planning to remove the supply pump today to clean it out and get it to prime. I'm sure there is still one clog I need to take care of. As they say when it comes to fuel injection, you need to make sure EVERYTHING is clean !

It turned out the shear pin for the fuel supply pump was broken. The two gears were still stuck the the pump body even after I got the cover off.

Well .... at least the tank will look better now. The spray paint arrived yesterday.

Thanks to everyone who hung in there with me on this one.

Just a quick follow-up.I re-installed the diesel fuel tank today poured in about 4 gallons of fresh diesel. It wouldn't start by itself but did make smoke. My standard 3 quick shots of Ether and it fired right up. Ran fine and idled lower without stalling than I ever remember. Clean fuel ... nothing like it.