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Bio-diesel and engine longevity
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=94&t=23553		 Page 1 of 1
Author:  grywlfbg [ Fri Aug 17, 2007 2:03 pm ]
Post subject:  Bio-diesel and engine longevity
This is a continuation of thread:
http://www.lostjeeps.com/forum/phpBB3/vie ... c&start=15

Reflex wrote:
A diesel is typically a half a million mile to million mile engine. 34k is not an appreciable sample size, even if a single owner could possibly be considered a representative sample.

As for studies, I have not claimed they exist for this engine publicly. As I said, a friend of mine worked on the engine, and I trust his results. I pass that info on and people can choose to heed it or not, their choice. I am not stating it authoritatively because the testing I am reffering to is not public(its military, actually).


Again, without knowing how rigorously the fuel was tested, what the base oils were, where it came from, etc. it's just hearsay (what does your friend know about BD?), akin to someone saying, "Rotella killed my motor!" Well, there are lots of factors that could contribute to such a thing. And again I say that bad dino diesel has killed a fair amount of motors too.

What exactly was his reason for how BD caused the failure? The BD should have been running through the same filters as dino so any particles should have been filtered out. As I mentioned before, if the refinery didn't remove all the glycerin that would definitely lead to problems but that's a refining problem (same thing would happen if a dino refinery left some tar or whatever in their #2) not a BD problem.

Bottom line is that you're correct in that there simply isn't enough useable data on BD to make any kind of accurate determination. It's my contention that most BD-related failures are due to quality issues but we'll just have to wait and see. If you don't want to risk it then that's cool, but don't go running around proclaiming we're all idiots for doing something that there isn't sufficient evidence to prove one way or ther other (want to talk about whether God exists?).

I'm not trying to be an stupid, I've just heard way too many "my uncle's cousin's sister used that soybean fuel and her truck blew up" stories for a lifetime.
Author:  Cowcatcher [ Fri Aug 17, 2007 2:17 pm ]
Post subject: 
This should be entertaining! :lol: :roll: :wink:
Author:  Reflex [ Fri Aug 17, 2007 5:04 pm ]
Post subject: 
grywlfbg - No offense taken. I've got no problem with scrutiny, after all I'm not offering up a solid piece of evidence, just my word. And honestly I don't expect most the BD people here to believe it, they were sold on the concept already, and I certainly would not change my mind just because someone on a forum gave me a piece of unverifiable information. The reason I put it out there is a) for those who come on and ask if there is any risk of damage running BD, I feel it would be improper to not say what I have heard especially since those who are claiming its safe have no better data than I have to back up their claims; and b) because all these bits of information over time will add up, and a case will be able to be built. If the information that is learned, even info that later turns out to be inaccurate, is not shared, we won't have a body of knowledge upon which to base our eventual authoritative opinions.

Now, to give you the details of the test I know about:

- The friend of mine is a engineer who works on military versions of engines, ie: consumer engines with some additional features for reliability sakes. The VM engine in our Jeep is actually used for some applications. His main focus as an engineer is endurance/long haul testing, they test engines to the million mile mark(if they make it) and measure them to determine what wore out and why.

- The purpose of the test in question is that the military has been considering switching to biofuels for political and diplomatic reasons. Easier to convince the locals that your not there for your resources when you can argue that your military is using home grown fuel.

- The only differences in the engines he tested was the fuel itself, which was according to him higher grade than the commercial stuff you can buy. Their standards were based on what the military itself would require for use, not what a co-op would consider acceptible. Obviously I only have his word for this, but then I only have his word for any of this info.

- In their test, the service lifespand of the BD powered engine was roughly half that of the dino powered engine. Furthermore, multiple fuel system components required repeated replacing, especially injectors which failed at a far greater than normal rate(I do not know the exact numbers). Furthermore, the engine itself showed signs of wear at nearly double the rate of the dino powered one, despite the added lubricity of the BD itself.

- The test was conducted with five engines on each type, to safeguard against simply a poorly produced model. The results were consistent on both batches accross all five engines.

Now, achieving 250k-500k miles with more frequent replacement of fuel system components may actually be fine by many BD proponents, after all thats still at the high end of what gasoline engines accomplish. As a result, for many people, this argument is purely academic. However, some of us like to think of diesel vehicles as the 'last' vehicles we will buy in thier class, and we don't trade in every decade. For us, the BD issue is a serious consideration.

Disclaimer - I am not posting this as a statement of fact. My only point is that as grywlfbg has stated, we do not have enough information on the effects of BD on this specific engine. This information is being contributed to add to the knowledge pool, and every member is free to give it as much or as little weight in thier considerations as they feel is appropriate. I will continue to bring it up however, as its what I know and when new members who are not familiar with this forum post I feel its wrong to not give them all the perspectives on the forum, as they are just as free to disregard my perspective as anyone else is.
Author:  flash7210 [ Fri Aug 17, 2007 8:40 pm ]
Post subject:  My experience...
This reply has nothing to do with bio-diesel and I don't want to take this
discussion of on a tangent. I just wanted to share my experience with
military engines regarding their longevity.


My experience from having been a mechanic in the Army tells me that
diesel engines in vehicles fail at a greater than normal rate!

I've seen many GM 6.2L in Humvees with warped heads and holes burned
through piston heads all at around 30,000 miles.

Many 908 Cummins that kicked rods and split engine blocks.

Many Continental v-12's that kicked rods, split blocks, and cracked
cylinders (although this is not that suprising because it is an air cooled
engine with an aluminun block and cylinders)


However, none of these failures had anything to do with the fuel systems.
Trust me, soldiers combined with mother nature can cause even the most
durable equipment to die at an early age.
(it is my opinion that bio fuels could not possibly do any worse damage)

The best engine I ever saw was in the old Deuce-and-a-Half and it was a
MULTIFUEL engine. Although I've never tried it, supposedly you could run
just about any type of fuel in it.

Disclaimer: I have not worked on any military vehicle since 1999. I have
moved on to more important work.
Author:  Reflex [ Fri Aug 17, 2007 11:13 pm ]
Post subject: 
Well, the test I am reffering to was not 'real world' in the sense that it occured in a lab in a controlled environment. However even had it been real world, the results would be relevant since they had a 'test' and 'control' group, which is how a real study is performed. Once again though, I obviously do not have a hard copy of results, so take it with a grain of your favorite substance.
Author:  UFO [ Sun Aug 19, 2007 12:30 am ]
Post subject: 
Reflex wrote:
Well, the test I am reffering to was not 'real world' in the sense that it occured in a lab in a controlled environment. However even had it been real world, the results would be relevant since they had a 'test' and 'control' group, which is how a real study is performed. Once again though, I obviously do not have a hard copy of results, so take it with a grain of your favorite substance.
If you do come across those studies, I among others would be very interested in seeing them. I know of nothing fundamental about biodiesel that would lend itself to shorter engine life, and what engine components in particular that would be susceptible.

I replied to a post on tdiclub.com to a person that was showing a graph of oxidive stability of biodiesel with the variables of temperature and pressure. He was convinced this was the definitive evidence against using biodiesel in a common rail diesel because it started to break down at 220C and 500 psi or so. I pointed out to him that the tests were done in a oxygen atmosphere, and since diesel #2 auto-ignites at 240C this was not a condition that exists in a common rail diesel. As a matter of fact my old Mercedes pressurizes the fuel higher than this with its mechanical injection, and it has zero issues with biodiesel.
Author:  flash7210 [ Wed Aug 29, 2007 8:20 am ]
Post subject: 
Just a thought...

What about adding some sort of fuel conditioner/cetane boost?
The stuff from Power Service for regualar diesel is supposed to prevent
gummy deposits that could occur from ULSD fuel.
Author:  grywlfbg [ Wed Aug 29, 2007 5:28 pm ]
Post subject: 
Sorry I'm just getting back here... Work has kept me busy as of late.

Reflex,

Thanks for the added info. A few fleet owners are swiching to Bio (my co-op in San Francisco has suceeded in getting the city to switch a number of their buses to B20 and a few are being tested with B99) so it'll be interesting to see what happens as these folks start racking up the miles.

flash7210,

BD is already at a higher cetane level (and has higher lubricity) than #2 diesel so that's not a problem. The most common problem is glycerin or other contaminants left in the BD after the reaction. Assuming it was refined properly per ASTM spec, the only issue I know of is that BD has a higher cloud point than #2.

There are BD-specific fuel additives but they are different depending on the base oil (soy, canola, etc) so it gets a little complicated.

Bottom line is that unless you're trying to store BD (in which case you need some biocide as it will turn rancid after 6 months or so) you don't need any kind of fuel additives.
Author:  ATXKJ [ Wed Aug 29, 2007 6:35 pm ]
Post subject: 
FYI - if you Google DOD tests and BioDiesel - you get a number of hits - and the data they report out is pretty mixed - they had some 100% bio that wasn't transesterfied, alge, no reliable method of measuring the biodiesel ect - a real mess.
I don't know if these were the same tests - but I'd argue any results were statements about the maturity of the industry instead of the nature of biodiesel.
Author:  Bill.Barg [ Sun Nov 11, 2007 12:35 am ]
Post subject: 
y'all have probably already seen this,

http://stage2.salessupport.com/chevron/ ... on_Mag.pdf

Interesting but typical anecdotal evidence of engine trouble with BioD. A picture of a slugged and burned engine, but no info on what type of fuel it used.

Still,,, makes me want to change the oil tomorrow.
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