Biodiesel is eating the fuel supply hose from my tank!
 

For those who use biodiesel, what have you done about replacing the short length of hose that comes out of the fuel tank? It has a fitting on one end that screws into the fuel strainer, and the replacement part from Mercedes is not biodiesel compatible. I believe that my hose is getting eaten from the inside out as evidenced by constant clogging of my prefilter with black specks that I do not think are fungus.

Does anyone know what thread size and pitch the fuel tank strainer has on the bottom where the fuel supply hose screws in? I may need to reduce and convert this down to 1/8" NPT so I can put a hose barb on it.

Dan,

There's a barb under the crimp ferrule on that hose. Gitcha some 5/16" or 8 mm ID hose that's bio safe. Drain the tank (I just run the tank low by driving, then place the under-hood return line into a 5-gal jug and let the engine pump itself dry). Remove the hose by loosening the worm clamp on the line end and then unscrewing from the tank end (17 mm?). Cruise over to the workbench and use all manner of dremels, die grinders, hack saws, tin snips, and whathaveyou to mangle the ferrule off. Cut off the remainder of the hose. Screw the newly-bare barb back into the tank. Install your new rubber (about 12" 300 mm maybe) and TWO worm clamps (you'll need one more than is on the car now). You'll probably want to change the return line then, too, but it already has two clamps so it's easy. The bigger 3/8" 10 mm line is for the tank vent, don't worry about it IMO.

I replaced all of the short hoses at the fuel tank of my '87 with Viton but It's been a couple of years and I don't remember exactly what I did. Don't think I had to change any metal fittings.

I used the grinder/cut-off wheel technique to expose the brass barbed fitting that is hidden underneath the factory crimped end.

As stated above there is a normal barb under the crimped fitting in the tank strainer. You can cut it off and put a normal piece of hose on. I'd suggest the SAE 30R9 hose. It's lined with viton and much more durable than solid viton. The barb fitting threads out of the tank screen, so you can take it off and work on it. This would also be a good time to remove the tank strainer and clean it. Make sure to put on a new o-ring before you install the strainer back in. I'd replace both the supply and the return while you're under there so you don't ahve to do it again.

Thanks for the tip on the hidden hose barb guys! I've had to drain the tank before to check the tank screen and could shoot myself for not changing the hose then! What a miserable job! I've got some of that SAE 30R9 hose. It was pricey at NAPA for like $8 per foot for the Gates brand. I need to find a better deal somewhere else. Also, does anyone know a good place to get a viton gasket for the tank screen? Might as well deal with that while I'm messing around under there...

Greaseworks sell 5/16" SAE 30R9 hose for $5.50/foot -
http://www.greaseworks.com/store/index.php?cPath=27_43_44

As well as a viton tankscreen o-ring for $2.50 -
http://www.greaseworks.com/store/product_info.php?cPath=25&products_id=321

go to gates.com and click on where to buy. Click on industrial distributors, they will be cheaper.

To get a better deal, wait outside until someone with a company truck shows up. Go in after they leave, tell the owner you work for the same company, but would like to make a personal purchase. When you quote the SAE 30R9 spec, you will be believed and get the lower price.

Tygothane
 

U.S. Plastics

Weird,
Dont give out too many tricks like that or every one will be doing it!! Probably if you ask nice, the sales rep would give you a foot of hose for trial purposes on your "special project"? That works from time to time.

Oreilly's has a high pressure rated fuel hose that has a blue liner that I have been told is good for use with diesel and biodiesel.

I've tried several different types of translucent fuel hose, and none of it stood up to biodiesel/WVO long term.

Tygothane (Saint Gobain is the Manufacturer)
 

http://www.plastics.saint-gobain.com/

http://www.tygon.com//uploadedFiles/SGtygon/Documents/Tygon_Tubing/PolyurethaneTubing-Tygothane-C210A.pdf

http://www.tygon.com/tygothane-polyurethane-c210a-tubing.aspx

OR

http://www.tygon.com//uploadedFiles/SGtygon/Documents/Tygon_Tubing/PolyurethaneTubing-Tygothane-C544AIB.pdf

Nice. According to the info above, looks viable. Where did you buy yours?
If you are using this product, for how long now and how exactly are you using it?

Thanks.

Bio or WVO? A single-tank conversion?

If the biodiesel is going through new hoses maybe it's the brew that's off, not the quality of the hoses.

I thought most modern hoses were alledgedly bio-resistant, with Viton being the trademarked "most resistant."