ULSD & Biodiesel

MicroRacer · November 6th, 2006, 07:21

I have to admit I'm afraid of this combination. In just lost the injector pump in my 1981 Rabbit Diesel Pickup. I have been running close to B50 all summer. After just one tank of ULSD and biodiesel, my injector pump has failed. The place that I am getting my injector pump rebuilt told me that he normally gets 13 to 15 injector pumps a month. He is now getting that per week and he is blaming ULSD.

In my wife’s car we have been running B100 all summer long and then we will go to B50 for a winter mix using kerosene, and some LSD. I plan on staying away from the ULSD until I find out more.

How does ULSD and Biodiesel affect the seals and do they affect them differently. I was hoping for closer compatibility, but I have a lot to learn.

tditom · November 6th, 2006, 08:23

When you say you "lost" your pump, are you just referring to leaky seals?

Switching to either biodiesel or ULSD after prolonged LSD usage can lead to seals leaking. To the best of my understanding, this is because the aromatics in LSD cause seal material to swell, which actually will push parts away from each other. When switching to either ULSD or BD, the seals shrink and may harden, leaving the components apart which causes the leaks. The good news is that when you replace the seals and stick with the new fuel, you shouldn't have anymore issues with seal failure.

When I first read that you lost your pump, I was wondering if you had issues with ULSD's lubricity, which may or may not be adequately additized enough to protect our pumps. If its just the seals, then I'm afraid that is the price of progress with ULSD.

MicroRacer · November 6th, 2006, 09:02

Quote:

Originally Posted by tditom

When you say you "lost" your pump, are you just referring to leaky seals?

My truck would run then shut down like it ran out of fuel. I put a electric pump on it hoping that it might be the fuel pump, but unfortunately that was not it. The guy at vwdieselparts told me that it was the seal inside the pump that went bad and that it was sucking air.

So ULSD and biodiesel react in the same manner on the seals? If that’s true then that will be great, because sometimes on trips we get stuck using petro-diesel.

scurvy · November 6th, 2006, 09:47

Quote:

Originally Posted by MicroRacer

I have to admit I'm afraid of this combination. In just lost the injector pump in my 1981 Rabbit Diesel Pickup.

It sounds more like the 25 years of being bathed in rotgut higher sulfur (bio)diesel then the switch to ULSBD is what caused the seals to fail to me. Not the fuel itself, but switching fuels

Quote:

Originally Posted by tditom

Switching to either biodiesel or ULSD after prolonged LSD usage can lead to seals leaking.

Correct. It's the switch - not the fuel itself - that can lead to leaking seals.

This kind of stuff happens every time there's a major switch in fuel formulation (leaded to unleaded gas, MTBE to ethanol, HSD to LSD, the first ULSD, etc).

IMHO a ULSD-BD blend is the best fuel you can run in your TDI.

scurvy

bmixon · November 7th, 2006, 15:25

Guys I am new to the forum and the Diesel world. I plan on having a used 97 Passat TDI delivered to my home near the end of this week. The gas station near my house sells only ULSD (Cetane 42). I had planned on filling up the Car there but after reading this should I be concerned??

tdisedanman · November 7th, 2006, 17:46

My wife and I both have TDIs. Hers is an 05 Passat and mine is an 05.5 Jetta. We both have used B5 since about the 5000 mile mark. Neither of us has experienced any leaks yet and we are now on USLD and B5 all the time. Hope my luck holds up!

scurvy · November 7th, 2006, 20:08

Quote:

Originally Posted by bmixon

...97 Passat TDI delivered to my home near the end of this week. The gas station near my house sells only ULSD (Cetane 42)

While LSD may still be available until 2010, ULSD is the future. I say go ahead and use it with reckless abandon - either the pump will leak or it won't. If it does, get the seals replaced and you'll be all good. Biodiesel has a similar affect on seals as high sulfur diesel (not due to aromatics - due to the aniline point, from what I've read) so low bio blends w/ULSD may help negate some of the problems with switching from LSD to ULSD.

One thing you may notice on here is that some people jump to conclusions and worry too much. Relax. Don't worry. Have a homebrew. Enjoy the Passat.

scurvy

tditom · November 8th, 2006, 05:59

Quote:

Originally Posted by bmixon

Guys I am new to the forum and the Diesel world. I plan on having a used 97 Passat TDI delivered to my home near the end of this week. The gas station near my house sells only ULSD (Cetane 42). I had planned on filling up the Car there but after reading this should I be concerned??

I advise you to use a quality lubricity additive when using ULSD, until we can figure out if it is being adequately additized to protect our FI equipment. see this discussion

fisch · November 16th, 2006, 19:32

Quote:

Originally Posted by tditom

I advise you to use a quality lubricity additive when using ULSD, until we can figure out if it is being adequately additized to protect our FI equipment. see this discussion

from biodieselmagazine.com
http://www.biodieselmagazine.com/art...81&q=&page=all

Biodiesel Blending
Blending biodiesel with ULSD has been touted as a good fit for two reasons, according to Paul Nazzaro, a petroleum liaison for the National Biodiesel Board. First, biodiesel is a clean-burning renewable fuel that contains no sulfur, so it can be added to ULSD without raising the new diesel fuel’s sulfur content. Second, because sulfur is a lubricant, ULSD requires additives that increase its lubricity. Biodiesel can achieve that. With those two factors in mind, Nazzaro considers the two fuels—ULSD and biodiesel—a handsome match. A lot of people thought the implementation of ULSD would cause the biodiesel industry to “fade into the background,” he says, explaining that he sees the situation quite differently. “ULSD gives biodiesel legs,” he says.

more stuff:
http://www.biofuelsforum.com/using_b...arranties.html

In France, all ULSD is mandated to contain 5% biodiesel, or another way of putting it is that all French diesel vehicles run on B5. Many of the major fuel companies in Australia are already using biodiesel as an additive to improve lubricity. Australian regulations state that mixes of B5 and under do not require any labelling or info to the consumer, so chances are that you are already driving with a small blend of biodiesel.

eyetdiman · November 16th, 2006, 19:54

What ever happened to the MN mandate of 2% biodiesel that was later withdrawn following many complaints?

tditom · November 17th, 2006, 05:15

I agree with using ASTM spec bd> 5% to provide adequate lubricity. I use B20 myself to provide this, among other benefits.

FredIA · November 17th, 2006, 07:16

The local station that sells bio (unless specially ordered) sells B2. Is 2% enough to increase the ULSD lubrication in everyone's opinion?

Certainly by spring I'm going to switch to "legal VW" blends (B2 or B5) of Bio.

Fred

tditom · November 17th, 2006, 08:54

Fred- look at this paper on bd and lubricity. At the top of page 3 there is a chart showing the lubricity benefit of various %BD on LSD. Note that the starting point of the D2 is a 536 u wear scar. [note that by ASTM standards (560 u wear scar max), no lubricity additives would be needed]. If ulsd is additized down to the same level this LSD is at, then B2 is probably good enough. I suggest at least B5, but that's just to be safe. As you can see by the chart, the lubricity benefits of BD above 1% are incremental.

homerdude · July 13th, 2008, 09:27

U guys are doing really good work!...I am a MS student in Indian institute of Science Banglore and i would like ask u ...which fuel is better ULSD or Biodiesel? nd why?

feverwilly · July 15th, 2008, 06:31

Better is too general a question; (My opinion)

Better in quality --

This varies.. Some make it themselves and really pay attention to quality and removing water or methanol, some dont. Josh Tickwell in his first BioDiesel book said it was okay to leave the Methanol in the BioDiesel. He has reversed his stance because of the harmful pollutants it causes.

Better in the winter--

If winterized (ULSD), it doesent gell at as soon at the lower temps. BioDiesel will Gell at 32F without additives and maybe as low as 17F with additives.

Better in the summer and against pollution --

BioDiesel provides more lubricity. The Pollutants it causes smells like french fries or chicken cooking and I have read tests where rats were exposed to BioDiesel fumes for weeks at a time and they thrived, I read the same rats died when exposed to ULSD after a few days. Hands down BioD is better in this category.

Better against pollution I'd say BioD