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Go Back   TDIClub Forums > VW TDI Discussion Areas > Alternative Diesel Fuels (Biodiesel, WVO, SVO, BTL, GTL etc)

Alternative Diesel Fuels (Biodiesel, WVO, SVO, BTL, GTL etc) Discussions about alternative fuels for use in our TDI's. This includes biodiesel WVO (Waste Vegetable Oil), SVO (Straight Vegetable Oil), BTL (Biomass to Liquid), GTL (Gas to Liquids) etc. Please note the Fuel Disclaimer.

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Old March 24th, 2008, 19:42   #16
TDICult
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A very important statement from the Fuel Injection Manufactuers that captures most of the issues associated with Biodiesel.

http://www.biodieselconsultancy.com/..._June_2004.pdf

Fuel Leakage
Fuel Filter plugging
Corrosion of components
Pump seizures
Reduced service life
Injector nozzle seat wear
Blocked Injector nozzles
Poor nozzle sparay atomisation
Injector coking
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Old April 6th, 2008, 18:22   #17
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Quote:
Originally Posted by TDICult
A very important statement from the Fuel Injection Manufactuers that captures most of the issues associated with Biodiesel.
...

Fuel Leakage
Fuel Filter plugging
Corrosion of components
Pump seizures
Reduced service life
Injector nozzle seat wear
Blocked Injector nozzles
Poor nozzle [spray] atomisation
Injector coking
It might be noted that these problems are those associated with poor quality fuel, in that all of them except the first are accompaniments of various fuel preparation problems, such as free water, methanol, fatty acids, sodium, potassium, and/or glycerol (glycerine). The first seems to be caused by rubber seals (even nitrile rubber is mentioned) being attacked by the fuel, and it does not appear that it is because of any problem with a bio-fuel.

Seems to me that these problems will be eliminated by careful processing. That is, the inputs must be clean, the resultant fuel must be washed then the water and waste completely extracted.

Hence, yet again, a strict warning to know what you are doing and be really careful and thorough about doing it.
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Old April 24th, 2008, 16:04   #18
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There is another issue that has come to light.

Waste vegetable oil can contain a significant amount of dissolved potassium and sodium compounds. These compounds can NOT be removed by filtering, because they are not present as solid particles. When burned in the engine, these compounds turn into tiny particles of oxides and salts - which collect on the exhaust valves and in the exhaust parts, then get recirculated back into the intake system through the EGR system, and then they collect inside the intake manifold and intake ports, and on the back-side of the intake valves.

Where sodium and potassium are present in the fuel, chemical treatments and "washing" are necessary to take most of them out.
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Old April 27th, 2008, 17:07   #19
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This is a good article about the potential effects of biofuel usage in DPF-equipped engines (example 2009+ Jetta TDI). The issue of oil dilution by fuel is not completely limited to DPF-equipped engines with post-injection, though. Some fuel dilution occurs even without DPF and post-injection.

http://www.biodieselmagazine.com/art...rticle_id=2290
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Old June 9th, 2008, 22:39   #20
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Quote:
Originally Posted by TDICult
This is not totally correct. B100 biodiesel is approved for use in most VAG TDI's between 1996 and 2003. I will scan my VAG user manual when I get to a scanner. Its only with the introduction of particulate filters that its fallen to B5 and even then you get conversion kits for these cars.
Example of a coked injector nozzle. My edit: photo is from a car which had run WVO.

Edit: owner of image has taken image down

Quote:
Originally Posted by TDICult

Quote:
Originally Posted by nicklockard

Volkswagen’s stated warranty policy which strictly prohibits the use of biodiesel blends over 5% by volume fraction for their present and current diesel technology offerings (as of 3/3/08.) .
This is not totally correct. B100 biodiesel is approved for use in most VAG TDI's between 1996 and 2003. I will scan my VAG user manual when I get to a scanner. Its only with the introduction of particulate filters that its fallen to B5 and even then you get conversion kits for these cars.
Quote:
Originally Posted by TdiCult

Add at request of member TdiCult.


See also

http://forums.tdiclub.com/showthread.php?t=210685

Not all user manuals say you can use Biodiesel
{Edit note: earlier response to this issue:}



Quote:
Originally Posted by nicklockard

Thanks for the clarification: while that may be true in Europe, it is expressely prohibited in North America because we only have *voluntary* biofuel standards. I'll make the clarification. (later...kinda busy)
Quote:
Originally Posted by Added by nicklockard on 080609:

For clarity, it should be noted that you are referring to European-sold VAG diesel models and specifically to the running of the EU-only specification E DIN 51.606 compliant biodiesel.

In North America, we have no biodiesel fuel standards other than voluntary compliance to a poorly written ASTM specification which is only concerned with blends of biodiesel and petro diesel.
Example of internal corrosion inside a fuel pump quantity adjuster. Moisture in the fuel is the probable cause. See post
http://forums.tdiclub.com/showthread.php?p=1189798


Last edited by nicklockard; June 17th, 2008 at 10:26.
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Old June 9th, 2008, 23:49   #21
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Quote:
Originally Posted by nicklockard
What constitutes a “normal” versus unhealthy looking engine?

Let’s fill this section in. Please contribute photos of normal/abnormal engine conditions, regardless of cause if you have them. Thanks.


\Bump for photo submittals. Please, if you're a Volkswagen diesel mechanic, post photos of normal and abnormal engine internals so that owners will know what to watch out for and how to recognize problems as they develop.

Thank you!
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Old June 17th, 2008, 16:20   #22
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Resized.
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Old July 11th, 2008, 06:39   #23
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New book on running a diesel engine on vegetable oil
Written by a guy who worked at Frybrid for a number of years. Link to the table of contents:
http://www.newsociety.com/./titleima...I000932_04.pdf

Link to info on the book:

http://www.newsociety.com/bookid/4000

At least from reading the table of contents, it appears that he is covering A LOT of bases when it comes to running vegetable oil in a diesel.


SVO



Powering Your Vehicle with Straight Vegetable Oil By Forest Gregg The benefits of straight vegetable oil (SVO) as an alternate fuel for diesel engines are many. SVO is cheap, carbon-neutral, uses a waste product, and does not depend upon centralized corporate infrastructure.
An experienced designer and researcher in the straight vegetable oil field, author Forest Gregg has worked for Frybrid, the most respected vegetable oil conversion company in the US. He has sifted through the masses of contradictory, erroneous, and confusing information on the subject, extracting the very best information available. Chapters include:
  • Vegetable oil sources, extraction and refining
  • Viscosity
  • Chemical degradation
  • Fuel properties
  • Contaminants
  • System design
  • Engine modifications
SVO is the only book available that explains exactly what is necessary to convert a diesel vehicle and how to do it properly. It gives readers the tools to sort through the different companies and online plans to find something that works well. While technical in nature, this fully illustrated book is very accessible. Each concept is introduced and described in great detail.
Designed to educate new consumers, it is also a resource for current conversion owners.
About the Contributor(s) Forest Gregg, a former researcher with Frybrid -- a leader in the development of vegetable oil conversion systems -- has worked as a designer, fabricator and installer of SVO conversion systems.
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Old August 22nd, 2008, 16:26   #24
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http://forums.tdiclub.com/showthread.php?t=221689

Quote:
Originally Posted by Updated Version (date 080821) of what is thought to happen in some WVO fueled engines



1. WVO enters combustion chamber from poorly atomizing nozzle.
2. WVO vaporizes but incompletely combusts.
3. Some hot, vaporous WVO oil pushes past stuck rings into crank case. "blowby"
4. Most of this condenses back to liquid WVO in the CC oil, contaminating it. Some of this enters the turbo bearing and weeps through it into the intake, as the turbo is designed to allow this slight seal weepage.
5. Some of the hot, vaporous WVO mist/gas (it's cooling now) gets sucked into the CCV system and makes it past the CCV into the turbo. The CCV puck and stainless steel wire mesh at the top of the cam cover are designed to condense CC oil vapors, not WVO oil vapors. At any rate, some of the WVO mist (now cooled to a mist) gets sucked into the turbo intake. It combines with some of the WVO which has wept past the turbo seals. The turbo compresses both sources of WVO through the intercooler. Next it gets mixed with EGR soot and gases and pushed into the intake.
6. By now the WVO mist has cooled and coalesced around EGR soot particles and congeals onto the coldest surface around: the intake ports, valve stems, and tops!
7. Gradually the intake valves gain a significant buildup of crud.
8. Moreover, the crud condenses in the ports and intake, clogging it and starving the engine of air. The swirl port design of the intake ports is compromised and air no longer swirls into the combustion bowl, which compromises breathing efficiency, power, and emissions. (cascading failure mode type.)
9. Some of the WVO blowby (incompletely combusted mist/gas) pyrolizes (incomplete oxidation) to carbonaceous crud in the ring lands and squish band and sticks the rings, compromising sealing and/or oil control rings's functions. If the pressure sealing rings are compromised, those cylinder's temperatures and pressures at end of compression stroke are lower, making it harder to ignite and completely combust fuel (any,) further exacerbating the situation and accelerating the phenomena (cascading failure mode type.)

10.
Quote:
Originally Posted by [I
aNUT[/I]]


Since the IP is getting fed 100C oil, the injection timing is very retarded which doesn't help with complete combustion in the least. The nozzles need not to be hosed before the buildup starts. --(Nick's note: cylinder pressures and temperatures are lower, at more retarded injection timings, further exacerbating incomplete combustion phenomena (cascading failure mode type.)){for newbies: The ECU pulls back timing in accordance with increasing fuel temps to control NOx emissions,}
11. It happens so gradually you never notice it until the car is "way down on power."

Note: #7 and #8 also happen on engines running diesel fuel--it's a consequence of the high EGR duty cycle and the turbo seal's weepage combining soot and oil mist. However, WVO fueled vehicles tend to get a significant buildup on EGR, intake manifold, intake ports, and intake valve tops and stems. Diesel fueled vehicles tend to get significant buildup on EGR, intake manifolds, but not so much in ports and on valves.

In general, vehicles which are driven under light loading "like a grandma" where EGR duty cycle is high, vehicles running poor fuel quality or higher sulfur fuels, and vehicles which are driven on light loading in cold climates or spend significant amounts of time below nominal operating temperatures (city driving or short distance commuting) will suffer a greater degree of buildup because under these types of driving profiles and driving styles EGR duty cycle is high and turbo seal weepage is also highest. Driving style/profile is most likely the dominant factor here. (credit to drivbiwire for teaching this point to many of us.)

Last edited by nicklockard; August 22nd, 2008 at 16:29.
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Old October 24th, 2008, 23:14   #25
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Could you make a comment about whether the TDI could run without damage on JP-8 or Jet-A fuel?

Thanks.
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Old October 25th, 2008, 10:27   #26
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Is the sulfur content guaranteed (<500 ppm for pre-2007, <15 ppm for 2009+)? No? then you can't do it.

Is the lubricity guaranteed? No? Do you know the exact quantity of a lubricity additive that can be used to get it in spec? No? then don't do it.
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Old November 19th, 2008, 07:41   #27
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One more thing to think about. It's a situation that until now I've only heard about, but now it's in black and white. A lot of workshops will not touch an engine that has had its fuel system modified to run veg-oil. (I can totally understand their viewpoint, too.)

Link: http://forums.tdiclub.com/showthread.php?t=229920 - thread explains what the issues are. In fairness, there are a couple folks who replied to that thread who state that they will still work on them and explain their terms and conditions.

My viewpoint is that before making major fuel system modifications, either make sure you can either perform ALL major diagnostic and mechanical work yourself, or have access to a mechanic who does not have an objection to the veg-oil fuel system - but if the extra spaghetti under the hood creates extra work for the mechanic or fuel leaks are causing a smelly biohazard that needs to be cleaned up, expect to pay hourly rate.
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Old November 21st, 2008, 10:42   #28
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Being involved with conversions from home oil heating to gas or electric heat , I see a lot of winter heating fuel oil ( referred as #2 vs. diesel fuel as #1 ) being recycled. Will it damage my '05 TDI if this alternative fuel were to be used on a temporary basis ? Also, we know ( gas ) petrol ages quickly and loses octane but what is the shelf life of diesel fuel ? Can an additive retain or gain back potency ?
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Old November 21st, 2008, 10:59   #29
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First part of question: Situation identical to that posted in post #25 above, and the answer is the same as post #26. (Nutshell summary: Don't!)

Second part: Diesel contains much fewer volatile constituents and the engine doesn't rely on them for cold starting. If stored in a SEALED container, diesel fuel will last millions of years. But if stored in an UNSEALED container - one in which there is any sort of venting to the atmosphere - the big issue is condensation. No amount of additive will remove excessive water contamination, and water can breed bacteria which will cause all sorts of other problems. Biodiesel/veg-oil has an additional situation in that it is biodegradable. What I've heard is that biodiesel is recommended to be used up within 6 months although that is probably very conservative and dependent on storage conditions. Raw veg-oil is equally biodegradable. Waste veg-oil ... you are on your own. Who knows what sort of contamination (and bacteria) you are starting off with.
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Old December 12th, 2008, 13:18   #30
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Chalk up another interesting failure mode. Read the whole of this thread ...

http://forums.tdiclub.com/showthread.php?t=230324

... and then read the whole of this one:

http://forums.tdiclub.com/showthread.php?t=233026

When one suffers a component failure - particularly a systematic and repeated failure (3 out of 4 glow plugs), it is important to ask WHY WHY WHY, because there has got to be some common cause behind it, don't just simply blame the component in question.
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