Asphaltene in Diesel Fuel

Geomorph · February 23rd, 2010, 20:23

I posted this in someone's TDI101 fuel filter question but I wanted to start a new thread specific to this question.

The fuel filter I changed in December on my 05 Golf (PD) had black fuel drain out of it. It turns out my in-tank lift pump was dead as well, so when I changed that out last month, I got to see the inside of my fuel tank. It was coated in black stuff like what I could see inside the fuel filter hole. Also, there were some drops of brown water inside of the dead lift pump that I noticed when I emptied the fuel out of it into a bucket.

I have been running the car on diesel with 5% biodiesel for the last year and have also included 4oz of Stanadyne Performance formula with every fill up for about two years. That stuff is supposed to take care of water by making it separate out easier in the fuel filter, but now I am wondering if it just makes it separate out easier into the fuel tank. In either event, I was also driving around for probably 3,000 miles, at least, with a dead lift pump. I think I read somewhere that a dead lift pump situation may contribute to excessive heating of the fuel (I'm not sure about this last one). Here is a website that I found that discusses the issues of heat and its effect on creating asphaltenes:
http://fuelschool.blogspot.com/2009/...l-filters.html

For comparison, I also recently changed the fuel filter and inspected the inside of my 02 Beetle (VE) fuel tank. The fuel filter looked much cleaner than the PD filter and the fuel tank looked clean. The tank was white-ish inside, no black deposits. The fuel filter was about the same age as the Golf filter and both cars had been run on the same fuel: B5 plus Stanadyne. So I'm thinking that my PD car heated the fuel a lot more than VE car creating the asphaltene issue. Having a dead lift pump in the PD might also have contributed to the issue.

My questions are:
Should I try to clean out my PD fuel tank by wiping it down or putting some chemical in the tank (any suggestions)?

Does it matter if I do nothing? Will the fuel filter just take care of it?

Will this stuff dissolve back into the fuel and maybe clean itself up with time now that I might have less of a heat issue (working lift pump in the tank now)?

Right now I have Chevron fuel with TechronD in the tank. Any insight appreciated. Thanks.

Powder Hound · February 23rd, 2010, 21:38

I don't know if those little guys are as sticky as asphalt, but I would think that leaving them in a particulate state that would allow them to be pumped to and collected by the filter would be best. I also think your theory about excess heat causing more asphaltines is probably correct, but I'm not an organic chemist, so I can't speak to that directly.

DanG144 · February 24th, 2010, 03:22

I can tell you that most PD tanks I look into have a black carbon looking coating on them.

Know one seems to know if it is from the carbon in the fuel pump brushes, organic growth, or some chemical reaction, and some seem to think that it is from leaking injector seals and orings.

Since I have never seen exhaust gasses bubbling in the return line, I think it is not injector seals.

I wipe the inside down with lint free towels, vacuum the fuel out. Ensure NO water is left inside.

Then I routinely treat with Power Service Diesel Fuel Supplement to solubilize the water, and treat about 4 times a year with PS BIOKLEEN to kill organics.

If you keep the water out, the organic growth rate is greatly reduced.

RalphVa · February 24th, 2010, 04:27

What you're finding in your older car's tank is probably tiny bits of aromatics that oxidized to some black material. With ULSD and the extra processing that it experiences (probably a final heavy hydrotreat), the aromatics are all but gone with the sulfur. What many will be running into is more wax formation.

I recently had troubles with my tractor cutting out as though it had water in the diesel. I changed out the fuel filter a couple of times and even got fresh fuel. Still had the problem. So, I siphoned out that fresh fuel from the tank.

What I found were some whitish/yellowish globs of (probably) wax near the outlet hole for the line from the tank. I fished them out with a grabber tool and discarded them. Refilled the tank and no problems since.

About the only thing that would dissolve these wax particles are 1) use additives to keep them from forming in the first place, 2) warm up the fuel or dissolve with warm kerosene. Kerosene will have far more solubility for the wax particles than diesel. You won't get the wax out short of waiting for summer unless you practice #1 or do #2. #3 is what I did, which is much more difficult in a car tank.

DanG144 · February 24th, 2010, 08:31

Quote:

Originally Posted by RalphVa

What you're finding in your older car's tank is probably tiny bits of aromatics that oxidized to some black material. With ULSD and the extra processing that it experiences (probably a final heavy hydrotreat), the aromatics are all but gone with the sulfur. What many will be running into is more wax formation.

I recently had troubles with my tractor cutting out as though it had water in the diesel. I changed out the fuel filter a couple of times and even got fresh fuel. Still had the problem. So, I siphoned out that fresh fuel from the tank.

What I found were some whitish/yellowish globs of (probably) wax near the outlet hole for the line from the tank. I fished them out with a grabber tool and discarded them. Refilled the tank and no problems since.

About the only thing that would dissolve these wax particles are 1) use additives to keep them from forming in the first place, 2) warm up the fuel or dissolve with warm kerosene. Kerosene will have far more solubility for the wax particles than diesel. You won't get the wax out short of waiting for summer unless you practice #1 or do #2. #3 is what I did, which is much more difficult in a car tank.

I think that it is just as likely organic growth. I have seen black thread-like growth and clear jelly fish-like growth, especially in diesel tractor tanks or farm fuel supply tanks.

Use a biocide such as Power Service BioKleen. I can buy it at Tractor Supply Company locally, before that I got it at the fuel distributor's office.

Geomorph · February 24th, 2010, 19:31

Thanks for the replies. Since I don't really feel like opening up my fuel tank soon, I am going to try just sticking with the Chevron fuel with the TechronD in it and maybe adding some Power Service. Maybe I will also put a can of Diesel purge in the tank every once and while for the extra detergent. Since this sounds pretty common in PD fuel tanks, maybe it is not something that is too much of a concern. Also, hopefully having a working lift pump will help keep the fuel from getting as hot and increasing the black stuff formation (assuming that is what contributed to it). I will look in the fuel tank some time (or sooner if my fuel filter prematurely clogs) and see if this approach is helping. If not, I will just wipe it out (lint free towels) and work to prevent it from happening again.

b4black · February 25th, 2010, 06:19

Asphaltenes is a name misapplied to black stuff found in diesel fuel. Asphaltenes would be huge molecules used for making bitumen and asphalt. They are not in diesel fuel.

Hydrocarbons in diesel fuel will oxidize and form gums and black particualtes. This is probably what you are seeing. Actaully, they are more likely from the 5% biodiesel than the ULSD.

MethylEster · February 25th, 2010, 07:51

Geomorph,

Do you buy the B5 at the Chevron station or do you " splash blend " your own ? I don't know if California has a B5 minimum spec like Minnesota does or not.

If you are splash blending, where are you buying the bio from ?

740GLE · February 25th, 2010, 07:51

should one who uses B5 use a biocide to prevent this? or is higher Bio use more likly to have problems?

Geomorph · February 25th, 2010, 20:08

Quote:

Originally Posted by MethylEster

Geomorph,

Do you buy the B5 at the Chevron station or do you " splash blend " your own ? I don't know if California has a B5 minimum spec like Minnesota does or not.

If you are splash blending, where are you buying the bio from ?

I buy my B5 at a station called Propel Biofuels that have several stations set up in my area. They also sell E85. So the B5 is pre-mixed and I don't have to do any splash blending. Here is their website: http://www.propelfuels.com/content/ California does not have any biodiesel in diesel fuel minimum spec like Minnesota. The station I usually go to is not out of my way since I pass it on my way to work. Anyway, I was filling up the 02 Beetle today and there were some guys from Propel at the pump (one was giving another a tour) so I asked about where their biodiesel came from and he said they get it from all over depending on price and that it is most often from recycled waste oil and is often a mix of various sources. They get their regular diesel from the same terminal as all the other stations in the area.

The Chevron fuel (with no Biodiesel) I am using in the 05 Golf right now because I was curious whether that little bit of Bio was contributing to the black deposits in its tank. I think it is interesting that I was running both of these cars on the B5 and the black stuff only showed up in the PD's fuel system. I think the other important ingredient is heating of the fuel. I know that my PD gets the return fuel a lot hotter than the VE since I have done diesel purges on both cars. It took me a few tries to do a full diesel purge on the PD because the return fuel got so hot. I ended up setting the can of diesel purge (with the fuel lines hooked up to it) in a bucket of ice and it worked like a charm. I also wonder if running with a dead lift pump for a few thousand miles resulted in even higher temperatures than normal and that contributed to the black stuff formation.

So I am taking the B5 out of the PD for now and have a working lift pump and will see if that helps the situation.

DanG144 · February 25th, 2010, 20:25

The fuel system turned black in PD's with straight ULSD. BioD is rare here. You have to go searching for it.

I did not start mixing B2 into the 05 until a few months ago. The filter and tank has always been black as a coal mine. I was curious to see if it would clean up with B2!

Geomorph · February 26th, 2010, 08:16

Quote:

Originally Posted by DanG144

The fuel system turned black in PD's with straight ULSD. BioD is rare here. You have to go searching for it.

I did not start mixing B2 into the 05 until a few months ago. The filter and tank has always been black as a coal mine. I was curious to see if it would clean up with B2!

From what you are seeing, do you think there is any correlation with dead lift pumps? Are you seeing the black stuff on cars with both working and dead lift pumps? This fuel filter was the first time I drained fuel that I did not want to put it back in the tank (because it was so dark) and I also happened to have a dead lift pump.

I don't think the bio is the main culprit but I did want to try the Chevron fuel because they are mixing TechronD into in my area. (I think this is the only area where this is being done in this country). I understand that this a pretty good detergent, so I want to see if it would clean up my black stuff.

ranger1 · February 26th, 2010, 10:02

This quote was taken from this site:

http://www.filtercouncil.org/techdat...dieselfuel.htm

> Q: What are asphaltenes?
>
> A: Asphaltenes are tarry, organic particles that naturally occur in #2 diesel fuels. Asphaltene particles are generally thought to be in the one-half to 2 micron range and are harmless to the injection system, as they are soft and deformable. Concentrations of asphaltenes in diesel fuel vary widely and can increase through heat and fuel oxidation. As these tiny particles pass through the filter media they tend to stick to individual fibers. A build up of asphaltenes is the normal mechanism that plugs diesel fuel filters, not hard particles.
> Reference FMC TSB-95-1R1

Geomorph · February 26th, 2010, 19:27

Since it seems that these black things increase through heat, does anyone have any opinion about whether bypassing the thermostatic T on the fuel filter could be helpful? I'm thinking that if the fuel filter doesn't get pre-heated, then cooler fuel going into the engine might equal cooler fuel coming out resulting in less particle formation (at least during the cooler seasons). I am thinking of using something like the Kerma Widget.

DanG144 · February 27th, 2010, 06:00

I think bypassing the thermo tee will have no effect.

Unless your thermo tee is not functioning, all the fuel bypasses the filter already when the fuel is warm.

With the fuel rails running through the head, we have trouble operating below the 90 C of the water jacket - and probably always will.

I would love to have a good fuel cooler before it goes to the filter (in summer anyway). This would need to have a thermostatically controlled bypass for winter operation.

I know some have done this.