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Things you can do to get maximum engine life from a VO converted diesel.
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(Work in progress)

In the A cautionary tale discussion (on a TDi engine that had to have its engine replaced due to problems that developed using VO fuel)Ed Beggs suggested that there are precautions that can be taken to help assure maximum engine life on VO fuel.

This is a major concern of my fleet conversion clients and has been a primary concern of mine for many years. I think what I have learned as I was driven by that concern may be helpful to others..especially if I can condense it and discussion that remains on topic results. So here goes.

Since VO fuel research began in earnest the same basic problem has been noted with substituting VO for petrodiesel in diesel engines. It tends to leave carbon deposits which either directly or indirectly damage the engine and eventually lead to rapidly acellerated wear and/or catastrophic engine failure.

These deposits generally occurr in three places...the injector tips, the manifold side of intake valves, and the piston (ring) lands/grooves. The process is generally referred to as "coking". Piston land Groove Coking is described at: http://www.websitetoolbox.com/...ics/vpost?id=1644578 and if individuals are interested I will create a separate discussion on the other two. It is sufficient to say here that injector coking generally tends to acellerate ring/land/groove coking and that ring/land/groove coking leads to the early demise of diesel engines run on VO.

In early testing of VO fuel engine longevity was very short. So short that VO was deemed to NOT be a viable alternative fuel. This was because VO tended to only partially combust due to its high viscosity at room temperature. The partially combusted VO tende to collect on piston sides and quickly damage the cylinder walls as well as do secondary damage to other parts of the engine. Reducing the viscosity of VO prior to injection by heating it dramatically improved the completeness of combustion but did not completely solve the problem.

But there are many things that individuals can do to delay ring/land/groove coking and the subsequent shortened engine life it causes.
The most basic are:

1. Do not convert engines in the last stages of their life or in need of major maintenence unless you consider them disposable. If you DO at least test your crankcase oil for polymerization so it can be changed often enough to prevent gelling and the secondary damage this causes.
quote:
To test for crankcase oil polymerization:
1.Retain about a cup of the used lube oil in a small jar.

2.Seal it up and refigerate overnight.

3.Tilt the jar to see if the oil flows at all. Since refrigerators typically are set at between 37-45*F it may flow like molasses or tar...but it should still flow.

If it appears at all jello-like it indicates polymerization is ocurring in your lube oil and that you should increase the frequency of your oil changes. If it remains jello-like after warming to room temp you may have advanced ring coking and should immediately determine if this is severe using compression tests before major engine damage occurrs.

2. Do not allow your injectors to become leaky. Leaky injectors speed up the ring/land/groove coking process since their effectivness tends to quickly degrade. Use very "dry" VO fuel. Even very small amounts of suspended water (add link to suspended water discussion) tend to erode injector tips and allow leaking.

3. Do not add "performance" chips or other "power" mods to your engine. These are designed with diesel fuel use in mind and are not well suited to VO fuel use. They tend to add more fuel to the combustion chamber and so hasten ring/land/groove coking.

4. Do not switch to VO fuel until your engine is at normal operating temperature. The cooler the combustion chamber (piston,head,walls) are the faster ring/land/groove coking progresses.

5. Make certain that VO fuel is as hot as possible (200°F to 275°F) at the injector inlet. This temp can ONLY be achieved by using the most powerful and efficient injector line heaters available. For more information on why this temp is neccesary take a look at THIS discussion. For links on where to obtain injector line heaters look HERE.

6. Make certain that your purge cycles are long enough to completely purge VO from your injection lines and injectors. Starting a cold engine on cold VO will hasten ring/land/groove coking even in an engine with no other issues.

7. Do not ignore the manufacturers regular diesel engine maintenence schedule or any symptoms (hard starting, increase in crankcase oil consumption, excessive smoking upon startup,etc) which might indicate that the engine is not running optimumly.

8. Have a compression test performed..or do it yourself..before you convert to VO. This will provide a good indication of how worn the engine is and possibly of problems that need attention before conversion. It will also provide a "benchmark" that can be used to compare later yearly compression tests to.

9. Make certain that your purge (diesel) tank cannot become too heavily contaminated with VO due to VO beign "returned" to the dieseltank during purge cycles. Starting cold engines on a high percentage VO "blend" contributes to acellerated ring coking much as cold starting on VO does.

There are other precautions that have been suggested in other discussions...but they are either strongly disputed or simply not practical in most cases.

Comments?
Please try to remain on topic.

This message has been edited. Last edited by: danalinscott,
 
Location: Central MN..Brrrrrr! | Registered: November 06, 2001Reply With QuoteReport This Post
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Here are some more from Eds list that I agree with and that are not strongly disputed:

1. Change lube oil more often, likely twice as often, as usual.

10. At the first sign of rough running, poor starting, reduced fuel economy, unusual increase or decrease in lubricating oil consumption, reduced power or unusual increase in black smoke, or any smoke, start investigation of possible causes.


YVORMV - Your veg. oil results may vary, see www.burnveg.com/forum
95 Dodge Cummins 4x4
Zero fossil house- 100% solar power and heat.
 
Location: N. Colorado | Registered: August 31, 2006Reply With QuoteReport This Post
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Thanks Sun,
The first is covered adequately under #1 and the second is now addressed in #7.
 
Location: Central MN..Brrrrrr! | Registered: November 06, 2001Reply With QuoteReport This Post
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I'd love to contribute:

1) add a bit about maybe doing a professional oil analysis every other oil change, or at least once in a while as this can also be a good early indicator of problems. I know this is different than your polymerization test, which should absolutely be done at every change.

6) add a bit about a purge cycle which actually purges back to the WVO tank, not just a simple switch to diesel which results in gradual contamination of the diesel tank.

Maybe a couple of points on WVO preparation as all the best practices in the world can be blown to hell by bad fuel. Smile
 
Registered: March 16, 2007Reply With QuoteReport This Post
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To test for crankcase oil polymerization:
1.Retain about a cup of the used lube oil in a small jar.

2.Seal it up and refigerate overnight.

3.Tilt the jar to see if the oil flows at all. Since refrigerators typically are set at between 37-45*F it may flow like molasses or tar...but it should still flow.

If it appears at all jello-like it indicates polymerization is ocurring in your lube oil and that you should increase the frequency of your oil changes. If it remains jello-like after warming to room temp you may have advanced ring coking and should immediately determine if this is severe using compression tests before major engine damage occurrs.
 
Location: Central MN..Brrrrrr! | Registered: November 06, 2001Reply With QuoteReport This Post
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Been reading this very interesting link.
My question? Does anyone know how much oil the IP holds? Guess it might be different from engine size to engine size. But average?

Then, how many percent of the oil/diesel is returned back to the tank under normal driving?

When I switch from VO to Diesel, I guess it is only the VO inside the IP which is mixed with diesel when new diesel arrives the IP, and then some of it is returned to the tank, until it is only diesel in the IP. Correct?

And in the other hand, switching from diesel to VO we will have a mix of diesel in the return line of VO.

By the way, my VO returning hose, is connected back to the fuel hose before the HE and that has worked well so far. (2000 km up to today)
 
Location: Sweden | Registered: February 07, 2007Reply With QuoteReport This Post



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Won't a UOA (used oil analysis) indicate fuel contamination in the [lube] oil?


______________________________________
'97 Ford F-350 7.3L PSD - Plant Drive kit
'84 Mercedes Euro 300D NA - Custom two-tank
Running on
vegoil and biodiesel since May 2006

 
Location: SF Bay Area | Registered: February 14, 2003Reply With QuoteReport This Post
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Well I am changing my ways since reviewing the suggestions above. I no longer run WVO with my chip set at anything over stock. I forgot what a dog it is on the stock setting Roll Eyes, but I'm dealing with it. I had a UOA after 4,200 miles and there was a slight elevation in sodium and potassium. It could be coolant contamination or water soluble acids. They were not sure. I since have started mist washing, but have not used any yet. I did put a lube sample in the fridge overnight and it flowed just fine at 36*. I will now shorten my lube oil changes to 3K intervals. But they did note that my engine wear looks fine showing no mechanical problems developing. Well worth the $22 cost for the UOA.


______________________________________
'97 Ford F-350 7.3L PSD - Plant Drive kit
'84 Mercedes Euro 300D NA - Custom two-tank
Running on
vegoil and biodiesel since May 2006

 
Location: SF Bay Area | Registered: February 14, 2003Reply With QuoteReport This Post
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I just revised Ed Begg's list of ways to make a Tdi not take a dump on WVO, to add info on lube oil analysis and water-test info, but I think it's good advice for any vehicle running on WVO:

How to Avoid Problems with a VW Tdi Converted To SVO/WVO:

1. Change lube oil more often, likely twice as often, as usual.

2. Get lube oil tested on a regular basis and use vegetable based motor oil.

(Uncmbusted vegetable oil that makes it’s way past the rings and into the oil pan can polymerize (thicken) the motor oil. Polymerize means “turn into a plastic-like substance” )

BioMot by Panofin is your only US choice for a vegetable oil based motor oil:

Panofin BioMot
http://www.panolinamerica.com/cms/en/states.php?state=CA

$200 plus S&H, for a 25L pail, so $10/quart plus S&H

Call Chuck Rampage, 805-486-6300 (California) or cell is 805-486-5180, fax is 805-486-6330

Blackstone Labs will test your motor oil, and send you sampling containers. http://www.blackstone-labs.com/

And this company sells a $20 vacuum pump that works by inserting a length of plastic tubing down the dipstick, and as you pump the sampling container from Blackstone is filled with motor oil: http://www.polarislabs1.com/Vampire.htm

3. Use two, and preferably 3 (for faster purge times), 3 port valves and a controller of some sort.

Two 3-port valves, if sequentially switched, will prevent cross-contamination of the diesel tank with SVO. See: http://www.plantdrive.com/html/faq.html#30, “Cross-contamination with a 6-port valve, a problem or not?”

5. Use the best fuel oil (SVO) and best prefiltering techniques you can.

You can buy a water-testing kit from Utah Biodiesel Supply: http://www.utahbiodieselsupply.com/biodieselwatertestkit.php
and you can use it to test your SVO for water.

See also: http://www.plantdrive.com/Used_Cooking_Oil_Fuel_4_18_07.pdf

6. Get the injectors rebuilt or exchanged at time of conversion. Get them removed and tested once a year or every 50,000 miles whichever comes first.

7. Do not add performance modifications such as power chips or modified injectors.

8. Do not even think of single tank on these unless it is a well proven conversion to fully optimize the engine for vegetable oil of the type you intend to use, and has been designed for your climate, and you are willing to follow all the recommendations of the supplier.

9. Follow all the recommendations of the kit supplier.

10. At the first sign of rough running, poor starting, reduced fuel economy, unusual increase or decrease in lubricating oil consumption, reduced power or unusual increase in black smoke, or any smoke, start investigation of possible causes.

11. Make sure you get that engine out on the highway, and give it a long hot run once in a while, and do an "Italian tuneup" (full throttle run) once a week. Avoid idling and low engine loads on SVO.

12. Ensure your SVO is hot enough, consistently, under all operating conditions, as much of the time as possible. 158F/70C target temp.

13. Make sure the SVO is not *too* hot (limit to 212F/100C.)

14. Cross your fingers, it is still not a guaranteed success long term, but maybe other TDI issues will get you before SVO does, and maybe you will save money, have fun, feel like you are doing the right thing environmentally and politically, and etc.

Craig


www.PlantDrive.com

1972 Land Rover Defender/Series Hybrid, 300Tdi, Two-Tank PlantDrive system: HotFox, Vormax, Vegtherm Standard
Wife's car: 2001 VW Tdi New Beetle: PlantDrive TwoTank system: Donut tank for start-stop, VegMax, Vegtherm standard, 3-3-port valves, controller
 
Location: Berkeley, California, USA | Registered: March 04, 2002Reply With QuoteReport This Post
<DCS>
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I have read countless warnings of ring coking but never yet read of a first had experience of it or seen a pic of a coked up engine. As such, I am a little wary as to how much of a problem this could be.
Has anyone here had an engine coke the rings up on veg or know of a picture of it?

I have never run my 300D on Diesel. The fuel tank was badly contaminated when I got the thing so the day after it came home, I pulled the fuel tank to drain and clean it and the car has never had more than about a liter of dino Diesel through it since that day 11 months ago.

Having read and been concerned about coking issues, my preventative was to fit a water injection system. I noticed a difference in the way the car went days after fitting it and after about 3 months, the car was a completely different beast all together. I can only assume that there was some sort of deposits in the engine when I got it as the improvement over time has been dramatic and only just leveled out in the last couple of months.

I know there is a lot of suspicion over water injection in Diesels over the cleanliness benefits and potential dangers of water in the oil etc, but I am completely and utterly convinced that it has worked for me and have had no hint of a problem through using it.

My system is rather crude and cost me less than $10 with the bits and pieces I had lying about but works and I believe works extremely well. At that price and an hour of my time, I feel it is the best and most beneficial thing I have done to ensure the longevity of my engine and trouble fee motoring on Veg.

Until recently I have been running blends and have fitted a HE some time back but just did a WVO conversion. I have no qualms about the odd quick shift to veg as I am of the belief that any problems this may cause will be cleaned up by the water.

With 50% methanol added to the water and no other adjustment, I was able to shave almost 3 seconds off my 0-35Mph time and .75 of a second with water alone. This is a very useful performance boost the water facilitates.
I don't run the meth very often, but it is a welcome boost on long trips when the old girl is loaded up and trying to climb hills.

I will never own a diesel car be it on veg or anything else without having a water injection system on it given what I have experienced with water injection on this car.
 
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DCS,

INteresting post on water injection. It deserves it's own thread.

More on topic, here's alink to the thread showing coking damage:
http://forums.tdiclub.com/showthread.php?t=186108

I can add another tip:
Drive between 2,000 and 3,000 RPM. Don't ask me why, I don't know. Just passing it along.

[Update: a BOSCH engineer revealed that in the VE pump, the high pressure piston wore EXCLUSIVELY above 3200 RPM.]

This message has been edited. Last edited by: jburke,


1-tank Elsbett VW TDI , 220,000 WVO miles.
http://ctbiodzl.freeshell.org/votdi.html
and a '92 F-250 with only a FPHE
 
Location: Ct,USA | Registered: November 19, 2001Reply With QuoteReport This Post
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DCS,

I'd like to learn more about your water injection system. I've entertained the idea in the past, but now I actually have the time to make one. My idea was a simple manifold sprayer using an activation switch under the acceleration pedal, powered by a windshield washer motor or something similar. What route did you take?

John M.


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1984 3/4 ton Chevrolet Suburban 6.2L - 120,000 miles on biodiesel/WVO (yes, that number is correct!)

1992 Ford F250 extended cab 7.3L ATS, propane injection, water injection - 55,000 miles on WVO

1980 Mercedes 240D - 2,000 miles on biodiesel
 
Location: Missoula, MT | Registered: January 07, 2007Reply With QuoteReport This Post



<DCS>
posted
Hello John,
This is an explanation I wrote of my system some months ago.

http://biodiesel.infopop.cc/eve/forums/a/tpc/f/97510148...501016691#4501016691
My System is basically a washer bottle with a switch under the pedal.
 
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Hi DCS,

I found that thread of yours shortly after posting my message. I read it through completely, and agree with you that a continuous water injection system is a terrible idea. I will be making a simple switch mounted relay for full-throttle applications.

You have the right idea in keeping it simple - if for no other reason than it works just fine as is!

John M.


-----------------------------------------------------------------------------------------------------------------------------------
1984 3/4 ton Chevrolet Suburban 6.2L - 120,000 miles on biodiesel/WVO (yes, that number is correct!)

1992 Ford F250 extended cab 7.3L ATS, propane injection, water injection - 55,000 miles on WVO

1980 Mercedes 240D - 2,000 miles on biodiesel
 
Location: Missoula, MT | Registered: January 07, 2007Reply With QuoteReport This Post
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You might want to also add some vehicle specific info, for example chevy 6.2 like an electric lift pump, mbs need special attention to the banjo fitting on the fuel filter etc.
 
Location: IL USA | Registered: June 16, 2002Reply With QuoteReport This Post
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My 98 jetta tdi has been running on a two tank system for about 5 months. Everything runs perfect- good power,starts,smoke level, following most of the suggestions from this forum. BUT I'm getting a TAPPING knocking sound. It's not there when the engine is cold. A few minutes into warm up the tapping starts like a valve lifter etc. The car has 332,000km.I'm getting scared. This could become a bad story on this forum. I put thru "Diesel Purge" to clean injectors- no change. Then I thought thin oil (synth 5w40) so I added "Lucas Oil treatment to increase viscosity when warm- no change.
Why is it quiet at start up until it gets warm????


99 A3 TDI. Two tank system . FPHE,6 port Pollack,HOH. 330,000km.
 
Location: NovaScotia,Canada | Registered: May 24, 2006Reply With QuoteReport This Post
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I just got back from the vw garage. They think it's the IP. It's not really distinct enough yet so they say keep driving it untill it gets worse. They say "you don't want to pay for an IP unless you're sure that's what it is" $$.


99 A3 TDI. Two tank system . FPHE,6 port Pollack,HOH. 330,000km.
 
Location: NovaScotia,Canada | Registered: May 24, 2006Reply With QuoteReport This Post
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Why are all these Jetta's having problems?!? Anyone with an old Mercedes having problems?
Or big trucks with high miles?


2000 F-250 7.3 with 160,000 on WVO, probably 10,000 of that in Biodiesel, total milage of 333.333 + !!
 
Location: Kenya, New Orleans, Massachusetts | Registered: July 19, 2006Reply With QuoteReport This Post



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How about advancing the timing? Would that increase engine life?
 
Registered: August 24, 2007Reply With QuoteReport This Post
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More frequent oil changes are no problem. What type and brand oil would be best? I started using synthetic when I installed my Plantdrive conversion and have been changing every 5-6,000 miles. Should I go to 3,000 with synthetic? What brand? Chris

.
 
Location: West Chazy, NY | Registered: April 21, 2007Reply With QuoteReport This Post
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