Poor performance on biodiesel in SDL
 

I have been running B100 in my 87 300SDL for a couple of months now, starting off with some mixing of BD with DinoDiesel. I've been noticing that the car had no pickup - once it got up to speed it ran really smoothly, but it had no power going uphill or when I tried to pass. I had chalked it up to fuel filters clogged or such and planned to check it out.

Well, the other morning I didn't have time to lug the 5 gallon containers of biodiesel to pour in, so I got regular diesel at the pump. I saw a nearly immediate improvement in performance. It is VERY noticeable that my car has much better pickup with dino diesel. I had heard that, to run B100, one should probably tune the IP, but I didn't have this issue with the 82 SD. Any ideas on why the incredible dropoff in performance?

I'd love to run biodiesel, but sheesh....

It could be a poor batch of fuel perhaps? On both my 300SD and my 2002 VW I notice no difference at all in performance between B100 and dino, but both engines sound quieter and smoother on B100.

You've checked that your inline fuel filter isn't plugged? Mine got pretty black, pretty quick after running Bio, it seems to shift the gunk from the tank. Wouldn't really explain why your performance instantly appears better on Dino though.

Kevin

Some cars are jsut sensitive to the marginally less power/energy biodiesel fuel has.

There's something like 8-10% less energy in BD than Dino.

In the 240D I notice the EXACT same thing as you. As the principle mechanic for the Boulder Biodiesel Co-op, I've dealt with the gamut of BD issues and run the fuel for a few years (off and on, more 'on' this year than any other) and have noticed this same phenomenon.

In the 300D Turbo, NO difference is detected between B100 and Dino. Probably because of the over-abundance of neck-snapping, tire burning, axle-shearing, raw HP available in that engine compared to the 240.

Try going to B20. It's a good compromise and you'll have your power AND all the benefits (engine wise anyway) of using BD. It'll also be fine for a winter fuel.

is your b100 homebrew or commercially made?

have you changed both fuel filters since switching?

my SDL loved it- no noticeable difference in anything (except no more smoke, and a different smell!)

Thanks for the insights. Yes, I changed the filters out after a couple of tanks of the B100. I haven't checked in the last few days, but didn't think that was the issue due to the dino fuel having more power. I am not driving that much these days, anyway, so I think I'll go to B20 with the remaining stock and wait until Spring to debug further.

Even with dino, it still doesn't have THAT much power. But then that's another issue.

Where did you buy your B100? or find B20 at a pump......B2 at the Liberty station on RT7 in Leesburg is the best I can find local.

I bought my biodiesel at Cropper in Berlin, MD. They have a drive up pump. We have a vacation place out there, so I've been filling up 5 gal cans on the way out of town and storing them in my garage. They sell B100. I don't think they sell B20, though.

We've found some questionable crud in the drums of b100 we get delivered- I now polish all the fuel I buy to prevent excess crap in the fuel system.

Has your low power come in cold-ish temps? b100, especially if soy based, will be thicker quicker than diesel-

I've noticed a drop in power in my 1980 300sd with b100. b75-80 takes care of most of the loss. I think that a partially clogged filter will allow the less viscous dino pass through fine when the b100 will slow easier because it is more viscous. you might consider changing your thermostat to a higher temp rating. this will allow your motor to heat the b100 more for moving through the filter, and for burning more of it. I'm not sure how good this is for the motor though.

I think the SDL is one car that you don't want to allow to get hotter than necessary?
Don't wanna mess around, with that aluminum head.

I got mine, specifically to try alternative fuels...
but I love it so much, I'm happy to use dino
and save the experiments for a lesser car.
( no bio in my area anyway )

I'd probably try commercial biodiesel...
but I'm not gonna use any homemade stuff,
until I get another car, that is more suitable for experimentation.

The fuel system has a thromstatically controlled heating element - higher engine temps will not have a direct effect on fuel temp.

I also buy my biodiesel at Cropper's in Berlin, they don't have a B20 pump but they do have a dino diesel pump right next to the Biodiesel pump, just pump 2 gallons of B100 for every 8 gallons of dino diesel and you will have B20.

I had the exact same low-power problems on my 2.5 turbo - the problem was the fuel tank strainer screen. The bottom half of the screen was blocked with crud but the upper half of the screen was relatively clear. When I had less than a quarter tank of fuel the car was very sluggish but filling up would immediately result in better performance. I'm guessing this is due to the fact that the fuel level now covers the entire screen leaving more effective area for fuel to seep thru into the collection lines. Cleaning the tank strainer immediately restored full power in my car - unfortunately cleaning the strainer is messy job.

The OM 60X series of engines seems to be very sensitive to delivery pressure - it's pretty easy to plumb in a low pressure gauge into the fuel line after the spin on filter and monitor your fuel system pressure. At idle pressure is typically 6-7 PSI and will increase to about 10-11 PSI at 2K RPM. If you are not seeing these pressures you have a fuel supply problem and your engine will not develop full power.

One thing I have noticed is that all commercial biodiesel is the same. I began using B100 in May and I did notice a slight power loss. A few months later my supplier changed their source. The B100 that I purchase from them now is better (power seems very close to that of petroleum diesel) and definitely cleaner. I question if every 'commercial' supplier is making biodiesel to the ASTM 6751-02 standard and even if everyone is making it to that standard I believe that you still have differences in 'power' per unit and cleanliness.

I can not speak to the B100 when comparing turbo to non-turbo usage as both of my Mercs are turbo.

I hope things improve for you.