constant crud in the pre-filter

[Doug183]

Here is the situation. I have been running my own homemade B-100 in a Mercedes Benz 1985 300D off and on for about 18 months now. Sometimes, in a pinch, I use diesel for a month or so. I bought the car about 2 years ago and replaced the the two lines by the gas tank with viton. I replaced the small intra-injector lines with viton. I replaced the cigar hose with a new cigar hose, but unknown if it is Viton or not. The in-tank screen was also replaced 18 months ago - when I managed to break it trying to remove it for an inspection. It was relatively clean. I also have put 3 ounces of "Kill-em" in the tank probably 3 times in the last year. I also sprayed cleaned all the hard plastic lines (I think they are all vacuum) with break cleaner 18 months ago to make sure they were all clean.

The issue is the pre-filter keeps clogging with black goo. That filter is needing to be replaced about once every 6 weeks. I just replaced the pre-filter today, and already the bio passing through it is much darker than the bio I put in the tank. I also did a diesel purge today: That is I made a little gas tank full of diesel purge (glass bottle), and connected a fuel line from it to the the fuel inlet (near the manual primer pump) and then the cigar hose also went into this little bottle. When I ran it, I could see the color of the returning bio, and it looks good.

My first thought is my biodiesel, but I have a VW TDI jetta as well, and although there is no pre-filer in that car, the big filter also clogs over time, but it lasts me 6-8 months.


Any suggestions?

Possible culprits:
1) Cigar hose is deteriorating as its not Viton and its putting rubber debris in the system.
2) The fuel line I bought at Autozone, although labeled Viton is not, and it is putting rubber into the system.
3) I got a bad infection in the tank and I got to add a whole bottle of Kill-em instead of a few ounces.
4) Although the tank screen was relatively clean, there is still a whole lot of crud left in the tank somewhere, that keeps making a mess of things, and I am going to need to wash out the whole tank.

[PhantomCadillac]

You need to pull and clean your tank. Run minerial oil through the fuel line and the return line followed by air do this till it comes out clean. Replace both filters and your problem should be gone.

[layback40]

There are plenty of threads in the diesel forum about bugs in the tank. Best you do a little searching. You will find stuff called startron (sp) is mentioned the most. Best you get some. Maybe there are quality problems in your bio production?
If you start with C##P WVO you will get C##P bio !

[oldsinner111]

It can take up to 9 months to get rid of diesel slime.I have fought it by using wvo.Then switching back to diesel you fight the dreaded chicken skin.I carry extra prefilters and spary carb cleaner to clean old filters.Also WD 40 to fill back filter with fuel.

[John Schroader]

I had much the same issue for a couple of years on my 300's. I know that my homemade bio was good, but pre filter life was shorter than I would desire - I could see the dark gook in the filter. After more than 40K miles of running bio through non-viton lines, I finally changed to viton - except for the line leaving tank (haven't found source of that one in viton yet). Anyway, now my prefilter fuel is no longer dark and I rarely need to change a filter. So -----it was fuel lines in my case. For whatever that is worth.

[Biodiesel300TD]

Originally Posted by John Schroader

I had much the same issue for a couple of years on my 300's. I know that my homemade bio was good, but pre filter life was shorter than I would desire - I could see the dark gook in the filter. After more than 40K miles of running bio through non-viton lines, I finally changed to viton - except for the line leaving tank (haven't found source of that one in viton yet). Anyway, now my prefilter fuel is no longer dark and I rarely need to change a filter. So -----it was fuel lines in my case. For whatever that is worth.

The supply hose has the barb that threads into the tank screen and the hose is crimped onto the barb. If you cut the crimp off, you'll find it's just a regular hose barb, which you can put a regular piece of hose on with a clamp.

[Doug183]

I am just going to pull the tank and wash it today. I will report back the results. A few links as well as Diesel Giants web page, seems to indicate this is the culprit.

[oldsinner111]

Pulling the tank is best.I just can't do that with mine(disabilities).

[Doug183]

Whoo.. Full of gunk. Not sure if it diesel sludge loosened by the bio or bacterial growth. My guess bacterial, because it was sticky and everywhere. Couldn't quite figure out how to clean it at first. Pressure hose at car wash did virtually nothing. I called around to a lot of radiator places to see if someone would boil it, but very hesitant answers. I also started looking to buy a new/used one but couldn't find one Anybody have any ideas on this just in case?

However, after letting the tank soak for a few hours with "Purple Power" and extra lye, looks like most stuff came out. I will then take it to the car wash again and power wash out the residue and see what happens.

[oldsinner111]

I'd put in a heavy chain followed by Grease Lighting or commercial floor wax stripper at one to 2 gals hot water.and slosh it around.Take out sender and clean too.

[layback40]

Originally Posted by oldsinner111

Take out sender and clean too.

X2
The only place I find gunk is in the sender, unscrew the end & take the tube off. Be careful of the 2 thin wires

[John Schroader]

Originally Posted by Biodiesel300TD

The supply hose has the barb that threads into the tank screen and the hose is crimped onto the barb. If you cut the crimp off, you'll find it's just a regular hose barb, which you can put a regular piece of hose on with a clamp.

Good to know. Many thanks.

[Doug183]

So,

After filling up the tank with purple power and lots of lye (Sodium Hydroxide - I make biodiesel so I have a big bag), things were a lot cleaner in there, but still not close to 'very clean'. You put your finger in there far enough and it was still sticky. Tie a rage to the end of a pipe, stick it deep in the tank and scrub a wall, and now black/grayish stuff would come off on the rag. Combined with the fact that there are only 2 usable tank orifices to shoot water into the tank, I felt pretty confident, no amount of car wash or even professional steam cleaning would clean this tanks.

I found a radiator place that would 'boil' the tank for $65.00. All I got to say is that it was so worth it. They even spray painted black the outside of tank for me. The inside of the tank is pristine. If there is ever a next time, 'boiling' is the way to go as between the car wash and chemicals, it already cost me 10 dollars as well as 2-3 hours of my time. (A lot of that was trying to figure out what chemicals to use and how to get various hoses in there.)

-fin

[Doug183]

Oh yeah, I cleaned the tank screen and sender unit as well. I have pulled the sending unit twice before to clean it, but this time, I broke the ground wire on the sending unit!! Luckily it was right near the bottom contact and I was able to solder it back on (not as well as I would like, but there is little tension on the ground wire) and thankfully it is working again.

[Renntag]

Now that the tank is clean, consider adding a dose of 'kill-em' to your finished fuel when it is stored. Also add to your vehicle to be safe.