Plantoil/diesel conversion basics
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danalinscott

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Reply with quote  #16 

The restriction is just a needle valve in most cases. The goal is not to restrict the direction of flow. It is to restrict the flow itself. I have even used short sections (2") of progressively smaller hose inserted into each other to "neck down" the existing hose to a 1/16".


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soshea00

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Reply with quote  #17 
yeah to a degree.  So you prefer a loop to a return to tank, yet leave a small orifice for return to tank.  Is that to relieve excess built up pressure or do you make that section physically higher in hopes that any air bubbles will go back in that direction?  Or is there some other reason that for that particular design?
danalinscott

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Reply with quote  #18 

It is a "limited loop" design which will allow any air bubbles present to be returned to the tank (with an air trap). It also helps speed the purge process compared to a closed loop configuration.


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danalinscott

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Reply with quote  #19 

This is a basic wiring schematic for this conversion configuration.


Please let me know if you have any questions.
For more information on the relays look HERE.
When power is supplied to them one output is "hot" when activated by a switch..and the other is "hot" when the relay is not activated.


In Figure 1 the engine is not running and the Ignition Switch is off.

In Figure 2 the engine is running and/or the Ignition Switch is on. Return fuel is being sent to the diesel tank.

In Figure 3 the engine is running and/or the Ignition Switch is on and BOTH dash switches are on. (The engine is running on VO and the majority of return fuel is being looped with a small amount being returned to the VO tank.
The electric fuel pump and Injector Line Heaters are on.

In Figure 4 the engine is running and/or the Ignition Switch is on and the purge cycle has been initiated. (The mix of VO and diesel is being looped and sent back to the VO tank. When enough time for a complete purge has elapsed the last switch should be turned off.

This schematic uses lighted dash switches to make operation as obvious and easy to track as possible. If you choose to use unlit dash switches you may omit the switch ground.

This is the most basic schematic.
It does not provide the fastest possible purge.
To accomplish that an additional 3 port valve is required as is a slightly modified wiring schematic.

In addition some simple automation is an option.
But again..this requires a few more components and modification to the wiring schematic.


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biostudent

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Reply with quote  #20 
Hi, I was wondering what size fittings I should get for the FPHE, I have a Mercedes as well , specifically a 1983 300D. I am using a couple components from greasecar and they seem to be 5/8ths. Just curious what you ended up using.

I was looking at the 10 plate or 15 plate exchanger on the site you listed... http://www.dudadiesel.com/heat_exchangers.php

Oh also, you mentioned the injector heaters. Any recommendations on a good place to get affordable ones?


danalinscott

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Reply with quote  #21 
Not sure what size fittings you need to buy.
You will need to measure the ID of your hoses and buy adaptors that will allow them to fit the FPHE you buy. They can have lots of different size ports.

As for injector line heaters I can only reccomend the ones linked to here.

There are cheaper ones but they really don't add much heat to the lines.



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mcarman

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Reply with quote  #22 

mr linscott,  i don't understand how the diesel return fuel gets back to the diesel tank?  i don't see where to cut the stock return line to install the 3way?  it looks like the return diesel comes from the ip and the leak-off pipes and goes to the socalled banjo bolt (one of three) on the filter.  how does it get to the diesel tank? does it get to the diesel tank?  the diagram shows it going to the diesel tank.  and if i plug that particular banjo bolt and cut into the return line of pump, then how would return diesel get to go anywhere at all since the banjo bolt is plugged.  obviously i am confused here.  i have your configuration suggested, the mb manual and a mb.  but i dont see where to cut and install the 3way valve.  help please.  pretty please.  sincerely,  michael carman

danalinscott

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Reply with quote  #23 


Quote:
i don't understand how the diesel return fuel gets back to the diesel tank? i don't see where to cut the stock return line to install the 3way?  it looks like the return diesel comes from the ip and the leak-off pipes and goes to the socalled banjo bolt (one of three) on the filter.  how does it get to the diesel tank?

If you can raise the car and look for fuel lines that come from the rear of the car (diesel tank) you will notice there are two. One is the fuel line FROM the tank..the other is the return line. The fuel line is routed to the fuel pump the return is not.

Quote:
if i plug that particular banjo bolt and cut into the return line of pump, then how would return diesel get to go anywhere at all since the banjo bolt is plugged. 


You don't plug the top part of the banjo bolt...only the part in that goes down to the filter. That hole is designed to allow any air that is in the fuel filter to escape to the diesel tank. Once you identify the return line and can follow it to where it connects to the filter everything should be much clearer.

Quote:

obviously i am confused here.  i have your configuration suggested, the mb manual and a mb.  but i dont see where to cut and install the 3way valve. 


You are not alone.
This is the part that confuses most.
But if you can identify the return line under the car and follow it into the engine bay the rest should become more clear.

You may be able to simply follow the line from the banjo bolt that does not lead to the injectors. There ARE two lines connecting to that bolt right?

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mcarman

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Reply with quote  #24 

i'm ready to hook up the electrical.  not sure how to get into the "ignition" switch or how to ground the 3 way and how to get thru the fire wall with wires for the switches,  etc.  is there  info on these details somewhere?  sincerely,   mcarman

mcarman

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Reply with quote  #25 

also,  is there anything wrong with a small gas type valve for the restriction in return line.  guess it's a small ball valve.  thanks   sincerely,  mcarman

mcarman

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Reply with quote  #26 

btw i finally have my mercedes running great on veggie conversion.  i can switch real soon compared to my three quarter ton ford, so i use practiacally no diesel.  almost free fuel.  i am pleased overall with mr linscotts plans and thankful for his personal help online

danalinscott

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Reply with quote  #27 

Quote:
I went to go buy the design for the heated pickup and it was a blind link.

How do I buy it?
thanks
michael


Just email me.

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danalinscott

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Reply with quote  #28 
Quote:
So, on with some questions. I liked the Fattywagons 2-tank mercedes diagram, and thought I would start there.  It would seem the "limited loop" you mention may or may not be similar to the fattywagons "on demand" loop solution. I never understood it (still don't actually) until I read your explanation that it sends the air bubbles back to the veg tank but keeps the hot VO queued up to inject. Is that true?


Yes..the return loop on diesel fuel systems is designe to send some fuel back to the fuel tank. It has the effect of allowing any bubbles of air which might find their way into the fuel lines to return to the tank rather than starve the injectors of fuel.

It has beena long time since I saw any of "Fattywagons" diagrams. They were not unique and usually represented whatever was being developed or discussed by other on the various forums. You will need to provide at least a link to whichever one you want to discuss to allow me to know what you are describing. And rather than post it here (where it may confuse people) please post it in its own discussion.

In this case discussing a different fuel system configuration might best be discussed in the "conversion configurations section.  Just follow this link http://voconversionbasics.websitetoolbox.com/?forum=57553 and then click on the tab in the lower right corner that is labled "New Topic"

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danalinscott

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Reply with quote  #29 

I doubt it.

But why do want such a large volume tank?
Do you plan to use the vehicle primarily for long distance trips ?

What about a couple of 6 gallon tanks and a warning light that you only have a gallon or two left?


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danalinscott

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Reply with quote  #30 
Quote:
20-25 gallons is not large.  It is normal, and the w123's come with tanks that size. 


True..but with the original (diesel) tank AND the VO tank you will now have a capacity of 40-50 gallons. And the VO tank will be further back in the vehicle than the original. This all negativly effects the handling charachterisitcs of the vehicle. Which in turn significantly effects safety.

That SHOULD be a primary concern that trumps the convenience concerns you have presented. Espscially in an older vehicle with a failrly worn suspension system.

Quote:
  I do not want to hoist two 6 gallon tanks about twice as often as I fill up 


Your choice..I am just presenting concerns you may not be aware of.

Quote:
When I asked about poly vs. aluminum, you replied that poly is better.  Now I am asking you how much better- is it worth this trade? 


Without answering the questions I ask I can't really provide good answers to theones you ask. If you plan to fill a large VO fuel tank and do not plan to use the vehicle primarily for frequent long distance trips You can expect problems with fuel polymerization in any metal tank. These will problably not be serious problems..only minor annoying problems. If I recall you plan to use the vehicle primarily for short trips. Which is why I suggested it would be better to use several smaller plastic tanks if you wish to avoid those problems entirely.

If you choose to use the large aluminum tank in a vehicle that will be used primarily for short trips I advise you to add a drain plug that will allow you to easily and completely drain the VO from it if you begin to experience frequent filter plugging.




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