Std fuel line with biodiesel? - PeachParts Mercedes-Benz Forum

TomJ · #1 10-02-2003, 01:01 AM

Have the beast up on blocks swapping a 4 speed in and the broken auto out and thought it would be easy to get to the fuel lines right now, but need some advice.

Two related questions;

Will standard (checker, autozone, napa, etc.) fuel line turn to mush with petro diesel and if so, where can I just pick up some fuel line that's safe for diesel (oil.)

Will the standard fuel line out there hold up to biodiesel and if not, where can I get Viton in fuel line sizes and pressure rated?

Thanks for any info. Promise to take pics of the tranny swap and post soon.

Habanero · #2 10-02-2003, 08:18 AM

I am not sure about compatability of the standard fuel line, but if you want a place to get replacement fuel line, try www.usplastics.com. That is where I bought my fuel line for my WVO conversion. They are really great to deal with and have reasonable prices, I think. They don't sell Viton line, but they have many, many compounds that are resistant to oils, aromatics, esters, etc.

BoostnBenz · #3 10-02-2003, 11:32 AM

If it is 'professional' produced biodiesel or normal diesel then a normal fuel line should work, but if it has any excess of methanol then you should without a doubt use the proper line like mercedes put on the car originally. It wouldn't take very long for the methanol to eat up a cheap line and make it start leaking. Do it once, do it right.

rwthomas1 · #4 10-02-2003, 06:53 PM

Mc Parts places all carry fuel line with a "fuel injection" rating. It has a higher pressure rating and has a liner to deal with the higher pressure and most any other substance. RT

TomJ · #5 10-02-2003, 10:22 PM

Thanks everyone for the help here. A few issues;

100% Biodiesel (of ANY type) is not compatible with original Mercedes fuel line (Buna-N or Nitrile) or any of the Mcparts fuel lines either (they are usually Bune-N or a nitrile compound. Biodiesel will make "goo" out of it.

I would really like to hear from people who've actually done this changeover and ARE using 100% Biodiesel. Need to find sources (other than McMaster & Carr) for Viton lines (which IS compatible with Biodiesel)

The issue is not a "fuel injection" or pressure issue at all. Also, fuel line is not compatible with oil service (like using it for tranny cooler line will decompose it, ANY of the common fuel lines, whether high pressure or not).

So the same generally goes for diesel (being, well.., an oil).

The problem is finding lines that will handle 100% biodiesel. So my original question.....????

BoostnBenz · #6 10-02-2003, 11:04 PM

Maybe I'm ignorant but I'm sticking by the MB hoses being durable with the biodiesel. Would you agree the seals in the IP or injection system as a whole can put up with it? Why would they do this and make the lines not able to withstand it?

TomJ · #7 10-03-2003, 12:30 AM

I would not agree that the seals can deal with it either. They also have a history of swelling and decomposing with long-term use of B100.

The latest (as in 1999 and later) MB's use a compound that can "supposedly" handle b100 use, but there is no empirical evidence yet to support that.

There IS much evidence, OTOH, that before ~1999, the hoses, seals, etc. that MB used WILL NOT hold up to b100 for any length of time.

Maxwell · #8 10-03-2003, 02:25 AM

What about Teflon?

Habanero · #9 10-03-2003, 08:28 AM

Good idea, Teflon would definitely stand up to biodiesel. It is not cheap, but usplastics carries it in many different sizes.

TomJ · #10 10-03-2003, 09:27 AM

Quote:

Originally posted by Habanero
Good idea, Teflon would definitely stand up to biodiesel. It is not cheap, but usplastics carries it in many different sizes.

Teflon would be great, but finding flexible line that would withstand the pressure has been a nightmare. There are few applications that require Teflon in high pressure apps, other (cheaper) materials are out there that fulfil that need so mfg's don't see a great need for it, but I'm interested if someone can come up with fuel line that is Teflon or TFE lined.

Teflon lined pressure hose would be the optimum.

Habanero · #11 10-03-2003, 12:01 PM

What size and pressure capacity do you need??? US Plastics has teflon (chemfluor) tubing in at least 3 different varieties in sizes from 1/16" to 1/2" ID and pressure capacities from around 20 psi at 185 degrees to 175 psi at 185 degrees. Go to their site and look around, you will find what you need! Be prepared, though, you will have to spend some cash to get the highest quality teflon tubing. If you don't see what you need, call them! They are great to deal with and very helpful.