Critique my veggie diagram - PeachParts Mercedes-Benz Forum

VegiBenz · #1 03-23-2006, 05:54 PM

Hello all. Here is my veggie diagram that I would like to implement soon. Look it over and see if there is anything seriously flawed. Keep in mind this is the schematic only, the components will be installed in a more logical way. Sorry the pic is poor, it was a screen grab from Excel where I drew it. My car is an '84 300D with 241k and it runs pretty good. Its ugly but it runs good. It won't let me attach the Excel file so e-mail me or PM me and I can e-mail it to you if you want. Thanks, Eric.

Old300D · #2 03-23-2006, 06:09 PM

It's similar to what I plumbed and ran for a while. With a shared filter, even though it allows you to share a lift pump and keep the factory plumbing for air-bleeding, your purge times will be astronomical. It took about a mile to purge the veggie to the point where it would restart cold.

IMHO, two fuel systems including filters should be separate right up to the injection pump.

orthotomeo · #3 03-23-2006, 06:29 PM

Make sure your heat exchanger will get you up to 170-180 degrees hopefully more.

1 mile isn't much of a purge, although it's not great.

biopete · #4 03-23-2006, 07:39 PM

it was too small. could you email it. I guess i could change my screen res to 800x600

i'll try that

bgkast · #5 03-24-2006, 02:40 AM

It looks like you have a separate primary filter for the diesel and veg, which then run to the lift pump. The way the stock system is set up the lift pump pulls fuel through a small pre-filter and pushes it through the spin on to the IP. You will need to either use the lift pump to pull fuel through each primary filter such as in your diagram, or add another 6 port and you can have the LP push the fuel through the filter for each fuel system like the stock set up. That is what I did. You can see my fuel diagram here: http://www.peachparts.com/shopforum/showthread.php?t=148416&highlight=tank+svo

VegiBenz · #6 03-26-2006, 10:51 PM

Let me pick your brains again. I did my installation yesterday and today. Everything was uneventful. When I turned the key finally, the diesel side was great but I have a definate power loss on the veg side. I used a new cube of oil from Sam's to get it set up on, by the way. As some of you said, there would need to be a separate pump on the veggie side to help it along. I wired in a Facet pump on the veg side at the tank and it did absoloutely nothing to help. It did prime and got real quiet and I have a little flow if I disconnect a hose up front but not much. I shortened the dip tube in the veg tank thinking it was sucking the bottom but it did not help either. Just to try and see, I put 5 gallons of diesel in the veg tank and drove it again and it did pick up on power and is drivable on the veg half. Not perfect but drivable. My facet pump, by the way, is the model 60106 I think and is a 4-7 psi model. I am using 3/8 tubing the whole way too. Can a Facet pump push cold oil or do I need a larger pump? Everything has been pentachecked and is hooked up proper. Every connection is leak free and tight. I personally think it is my facet pump but I need some more input. Thanks! Eric.

bgkast · #7 03-26-2006, 11:09 PM

What kind of temperatures are you reaching with your oil just before the IP? Have you checked for any air leaks? If you have not you should install some clear tubing before the IP and check for air bubbles in the system.

sodapop6620 · #8 03-27-2006, 08:38 AM

Your diagram does not show that you are heating the veggie tank. Are you heating the oil in the tank and prior to the IP?

Also, where are you tapping into the coolant line? I am getting the parts together for a conversion myself.

thorsen · #9 03-27-2006, 10:41 AM

Quote:

Originally Posted by bgkast

You will need to either use the lift pump to pull fuel through each primary filter such as in your diagram

I was thinking of two seperate systems right up to the injection pump. Ie, diesel flows through the stock pre-filter, lift pump, secondary filter and then the IP. VO flows through a seperate pre-filter, a seperate electrical pump, a seperate heated filter, and then the IP.

Valves would be on the fuel line going to the IP and on the return lines before the stock secondary filter.

Are there any suggestions for an electric pump that would be able to handle the heat and VO?

Bill()C · #10 03-27-2006, 11:13 AM

To answer an earlier question... No. The facet pump will not pump cold VO.

I'm surprised you are using a pollack valve. Seems more and more are reporting failures with them over time. If I had to make the choice I'd chose the Frybrid valves.

As for your current problem... I think you have an air leak or just stubborn bubbles in the line.

Bill

orthotomeo · #11 03-27-2006, 11:18 AM

Even if your final heat exchange is warming the oil, if your tank oil is cold you'll still have all the resistance of fudge to work against. Make sure you have some kind of heat in your Veg tank to at least warm the oil enough to take the load off your veg pump.

VegiBenz · #12 03-27-2006, 02:31 PM

Thanks for the replies so far. To answer a few questions from you guys in no order. I am using the Pollak valve since it was a one stop shop and a good deal. I was not aware of the failures until now. I am heating the oil with a HIH that I made with 3/8" for fuel and 3/4" for coolant (both copper) with an extra branch for about 10 twists of 3/8" copper around the veg filter. The oil is definately heated as it exits my HIH. I don't have any way of measuring it but it is pretty warm. I double checked every connection for leakage and possible sucking air and I can't find any. And yes, I am not heating the veggie tank (yet). I have seen other peoples diagrams with no tank heat therefore I thought it would work. I thought I would try the facet pump since I had it anyway but I guess it doesn't have enough wheaties to push. I did take the hose off of it and blow with my mouth and actually pushed oil so I know its possible. I think I can only generate 1 psi myself so I am sure I can find a pump to push it. I really don't know where I can route coolant hoses all the way back there so I hope to either not have to or find some sort of electric tank heater or just a 12V heater to go around my dip tube. Thanks again everyone. Eric.

bgkast · #13 03-27-2006, 03:06 PM

Check the thread I posted for a way to route coolant hoses back to the tank with no drilling of the body. It is not too hard to do. I think you may need more heat in the system. I have a coolant wrap around my filter, 16 plate heat exchanger, in tank heat exchanger and 10 feet of HIH and am getting in the 150 F range. 160 is Ideal.

VegiBenz · #14 04-15-2006, 04:11 PM

Well, I finally got the car to run on veggie!!! After installing a Holley blue pump at the veggie tank and having fair results, I was still getting air from somewhere. I was about to take a match to the whole thing and actually drove the wife's car most of last week in disgust. After researching more and hearing your comments too, I still stayed with the Holley pump at the veggie tank and the factory lift pump for diesel. After finding someone elses diagram on the web, I decided to try it and it worked. I am no good at posting pictures as I found so here it is in text.

Veggie Circuit=Veggie Tank-->Holley Pump-->HIH-->Goldenrod Filter-->Pollak 6-Way-->Injection Pump-->Return to Pollak Valve-->Return to Veggie Tank.

Diesel Circuit=Diesel Tank-->Lift Pump-->Filter-->Pollak Valve-->Injection Pump-->Return to Pollak Valve-->Return to Factory Air Bleed (Banjo Bolt)-->Return to Diesel Tank.

This way, when on diesel, the factory fuel system will work as designed except for passing through the pollak. When on veggie now, the veggie return bypasses the banjo bolt entirely and returns to the veggie tank. The lift pump can pump away happy without deadheading since the banjo bolt is now open again. It just pumps diesel from the tank through the filter and back out the air bleed/banjo bolt. The veggie pump is an on-demand pump. The only drawback is the little injector return hose still returns to the diesel side regardless of which fuel is coming in. I am cool with this short term, I will probably use some brass fittings and make up a return for it to be in the correct fuel system as well. Thank you again everyone. Eric.

tram · #15 04-15-2006, 04:46 PM

If you mix 10% kerosene with your veggie oil, you'll have much better flow and won't be so dependent on heating the veg oil. I used an electric fuel pump from a 1970s CIS VW which is a much higher pressure pump, virtually eliminating priming issues and "topping out" of engine speed, and used a W123 electric auxiliary waterpump in the lines for the tank heater. You have to be sure to have a switchable fuel feed AND RETURN if you're going to use the high pressure CIS pump. Most electric pumps designed for carburetted cars can't move the thick veg oil efficiently enough. Ran my 180D like a rocket. Well, a very slow rocket. I mean, it IS a 180D!

I'm going to put a huge aux tank under my O309D Executive Westfalia soon.