Need advice on Biodiesel

[SMacDonald]

I have heard a couple of diffrent things regarding biodiesel. I have heard that I need to convert all of my rubber parts that will come in contact with the fuel to newer type stuff, and I have also heard that it does not matter as long as the bio has been properly washed. I have a case of fuel filters at the ready, but have been put off by the thought of replacing the rubber in the injectors, the shut off pump, the fuel pump, the fuel lines and the fuel float for the guage. I have a 1976 300D that apparently had the engine rebuilt in the early 1990's (no proof of that, and the odometer only has 5 digets, so no idea of the real milage). Any comments or clairifications?

[sailor15015]

I run straight bio in mine and I haven't had a problem with the lines being eaten away. However, I do have a 1981 Datsun diesel pickup that my brother bought to try out the whole alternative fuel thing. It sat all this winter and when my step dad popped the hood to get it ready for spring almost all of the lines were leaking. I haven't had any problems with my hoses but I also occasionally put in dino diesel and my car never sets for more than a day or two. Good luck with your experiments.

I've run 100% biodiesel in my 300SD and none of the lines haven't gotton soft yet. I imagine eventually they will start leaking and getting soft however its the alcohol in the biodiesel that tears up the non-viton lines.

I don't think there is anything in the inject that you need to worry about replacing...they seem to run the vegitable based oils without any problem.

[Jimmy Joe]

Originally Posted by SMacDonald

I have heard a couple of diffrent things regarding biodiesel. I have heard that I need to convert all of my rubber parts that will come in contact with the fuel to newer type stuff, and I have also heard that it does not matter as long as the bio has been properly washed. I have a case of fuel filters at the ready, but have been put off by the thought of replacing the rubber in the injectors, the shut off pump, the fuel pump, the fuel lines and the fuel float for the guage.

BD will eventually eat soft rubber. Even the ASTM pro-made stuff. But the rubber we have observed weeping is the injector flow lines, and the regular fuel lines. I have not seen any trouble with the pricey stuff you mention. I just replaced with regular MBZ fuel line, which I am told is by nature BD resistant, if it was made after ~1998.
Have yet to see another leak.

[Kalanu]

One approach that a friend of mine with a bus takes is this: he buys all the replacement rubber and replaces it as it leaks. That way he doesnt have to do it all at once and he gets the full life out of the rubber.

[Jimmy Joe]

That is what I did. Although, I have heard the arguement that if you wait until the lines are degrading, after the filter, you risk putting some junk into the delicate clearances of the IP. Hmmm.

Originally Posted by Jimmy Joe

That is what I did. Although, I have heard the arguement that if you wait until the lines are degrading, after the filter, you risk putting some junk into the delicate clearances of the IP. Hmmm.

There aren't any rubber lines after the filter are there? (except for the injector return lines...)??

[TomJ]

Originally Posted by SMacDonald

..... replacing the rubber in the injectors, the shut off pump, the fuel pump, the fuel lines and the fuel float for the guage. I have a 1976 300D that apparently had the engine rebuilt in the early 1990's (no proof of that, and the odometer only has 5 digets, so no idea of the real milage). Any comments or clairifications?

First off, even properly washed ASTM B100 will cause rubber (Nat rubber, Buna-N, Nitrile, etc.) issues eventually, un-washed will cause them much sooner.

For the specific items (we do this "conversion" a lot); there are no rubber components in the injectors, the shut-off does not have rubber parts that contact fuel, the fuel pump does not have rubber parts that contact the fuel that you need to be concerned with (there are a few seals, but many years of running B100 does not harm them - not in the IDI MB engines), the float has no rubber parts (plastic, but the plastic used is not affected)

The things you need to watch (just leave them in and run the B100 till they start to seep) are the return lines (about $4 worth, take 10mins to replace) and the fuel line to the IP (with the secondary filter in it) - again, about $4 worth of line (or less) and about 10mins to replace, and the return lines at the tank (see last comment above - two short pieces of fuel line), and the feed line at the tank (with a crimped-on thdd fitting.

Don't worry about the fuel filter housing or the cigar, they never seem to have problems with B100.

In that old of a car, it probably needs ALL of these lines replaced anyway, so it's not a great loss as they will probably start leaking (if not already) with regular diesel.

These engines are the easiest to run on biodiesel as they see the least ill effect from running it and take to about any fuel readily.

Also, you can run B20 without effect for a long time.

[TonyFromWestOz]

These fuel lines degrade even when using diesel. Buy some spare and check for leakage when doing routine maintenance on the car.
Most of the fuel lines I have had trouble with were lines I re-used from parts cars (shops shut, needed hose). They were diesel degraded before I put WVO or biodiesel near them. Those lines where I installed new hose were still in excellent condition 4 years later.