trouble bleeding air on 300SD WVO conversion
 

Help! I've completed a Plantdrive WVO conversion on my 85 300SD (seems a good system for in the cold climate of Southern Ontario) and I'm at the stage of bleeding the air from the WVO fuel lines, but I can't seem to get all the air out and it won't run on WVO. Have I done something wrong, or just not tried long enough? (If you read down far enough, I describe the system I installed)

In order to bleed the air from the WVO line:

I first openned the banjo bolt at IP and pumped primer until air was bled and solid WVO streamed out. Engine would not run on WVO, only on diesel.

Second, I loosened banjo bolt on return line on top of primary filter and pumped primer to try to blled WVO air, but I couldn't get the air out. This worked for diesel bleeding, but not WVO. I also I disconnected the WVO return line (it's a looped system) and ran the engine, (as suggested by Plantdrive). This actually worked and the car ran for about 5 minutes, with return WVO dribbling into a jar. Not much of a return flow, and I understand these Benz's have a high return flow rate. but when i reconnected the return line, air was in the system and now i can't get it out.

My question: Why would it bleed air from WVO at IP banjo bolt but not at primary filter return line banjo bolt? It worked to bleed diesel lines, but not WVO lines.

It seems the lift pump is not drawing WVO fuel, but I can't see why. The WVO tank is nearly full, there's a good vent to the tank, the fuel line (3/8 rubber Gates XL fuel hose) isn't kinked and it has a new Racor filter.

What else can I do to get the air bled from WVO and be sure the LP pulls fuel from WVO tank? Is a hand vacuum pump that much more effective?

How I installed the system:

The kit I used:
A Plant drive system which uses HOH coolant heat to rear WVO tank, and Racor coolant heater/filter/moisture trap unit (called the "Vormax") and a Vegtherm inline electric heater. A 6 port pollack controls fuel selection and the WVO return line is looped back into the WVO supply. I mounted the Vormax behind the DS headlight and the pollack on the DS fender. I tried to keep the fuel lines (3/8 Gates XL rubber fuel hose) as short as possible without getting kinks.

This is how I plumbed the system for fuel flow:

Diesel tank - prefilter - primary filter - pollack valve - through vegtherm (not heated while on diesel)- lift pump - injection pump (a short Gates fuel line loops up and around to connect LP and IP)

WVO tank - Vormax - pollack valve - vegtherm - lift pump - injection pump

For return fuel from the top of the primary filter, I used a solid bolt so that WVO does not contaminate the diesel fuel in the primary filter. Return lines from injection pump and injectors were left stock. Therefore, both fuels return from injectors and IP to the banjo bolt on PF and then back to the pollack. At the pollack valve, the diesel goes back to diesel tank and the WVO loops back into the WVO supply after the vormax and before the pollack WVO inlet.

Have I done the system correctly? I followed the Plantdrive instructions closely. Could this have an effect on my bleeding problem? For those of you who read this far and reply, thanks!

I'd start by going over every clamp again. Making sure they are tight -- but not too tight -- and that the clamp is not too far from the end of any fitting. It only takes one bad one.

You didn't mention anything about using a purge mode to prime the system. Can you purge with diesel back to to veg tank and then run on that diesel?

How warm is the vo that is making it into the bottle? Just a vormax and a veg therm on this setup? My Merc has a hot fox fuel pickup, heated fuel filter, and a flat plate. I needed to add a veg therm to run the car in temps below 30.

Good luck!

I did check my clamps but I'll go over them again. Is there an easy trick to determine if a connection is leaking from the vacuum?

I'm not sure what a purge mode to prime the system is, but I assume you mean sending the return diesel fuel back to the veg tank to thin the WVO? I've already helped my WVO by starting the system on a 50/50 mix of new SVO and diesel fuel. I figured this would help get the system going.

I run a hotfox and heated filter unit, both by engine coolant as well as the vegtherm. The car has been sitting in a heated garage the entire time I've been working on it. Yea, it's a real benefit to have a heated shop!

Any other suggestions?

i had a lot of problems with air in the system. i ran a electric fuel pump at the tank and returned the vegi side back to the vegi tank . this way any air in the system will be bleed out in the tank . no problem`s with air since. good luck Rick

What kind of Oil do you use?
 

Don DS,

How cold is your oil and what kind is it? Where abouts are you in Ontario? I have a 240D in Central Ontario and have been through all kinds of problems with the kit I bought from a US seller as soon as winter came around. I have always had problems getting air out of my system in my mercedes as well, especially after I first installed it. I use two three port valves which I can operate independantly and my setup is similar to yours but I have a few extra things that help with bleeding air. My modified system has a boost pump for the wvo in the trunk. I turn this on and have a bleeder valve that I open under the hood, this gets all the air out up to my IP. I then start on Diesel, switch to WVO when the temp is appropriate but I control my valves independantly so I can return the WVO. Returning the WVO for 5 minutes of idling usually clears the air from the IP and injector hard lines. I then just simply switch the valve back to looped.

I wonder if there is a problem with your WVO being too thick. I run a heated fuel pick-up, HIH lines, two coolant heated filters and a veg therm and have a hard time getting to 150F in -15C weather on the highway. I admit though that the kit that I bought has too much unnessicary hose in it. I plan on gutting it and starting over with my own tested design soon. I will soon be adding a FPHE and should be good down to -30C or better. What kind of oil are you using? If I run sunflower oil in steady -15C I have problems. I have better luck with my small supply of Canola in the cold weather. Take your settled and filtered oil and put it in a mason jar, leave it outside for a few nights and see how it moves when you tip the jar in the morning. My sunflower oil is solid, but the canola oil is like thin motor oil at -15C.

Will
www.veggiefuelsystems.ca

I still need to figure out how to get the air out effectively. I think I'll try disconnecting the WVO line from the tank and making sure I can draw WVO through the lines, Vormax and pollack. I'll first try using the stock primer pump but if that doesn't work I may have to spend the $$ for a hand vacuum pump. :confused:

Rick - I'd prefer to loop my WVO return and this should work, but even so to bleed the air I've been returning the WVO to a jar and this still hasn't worked yet. Must be air somewhere ...

WillJayC - I'm just in the start-up stage and right now the oil in my WVO tank is a 50/50 mix of new canola and diesel. I'm not yet driving the car on WVO. I can't see that it would be an oil problem at this point. Plus car is in a heated garage so it's warm already.

The oil I plan to use is canola I've been collecting from a Chinese food place. I let it settle for weeks in my basement (food sludge collects at bottom, top 3/4 seems to be nice amber oil). Then I filter it through a paper and felt filter. I left some of this WVO outside for 4 hours and it was partially gelled, but it still flowed when I poured it. I'll start using this oil once I get the car running on the SVO/diesel mix in the tank!

willJayc - I just checked out the link to the veggiefuel systems. I wish I had seen it before I bought my plantdrive kit! Thanks.

I used a Grease Car system and it's been working find since Nov. 2006
www.greasecar.com

boost pump needed for weak LP
 

Will, What type of boost pump did you use? I'm thinking that's what I need. I'm pretty sure my LP is weak and not pulling the WVO (even though it's a 50/50 mix of new SVO and diesel). The primer pump will draw the WVO from the tank, and through the vormax. I bled the air this way at the banjo bolt on the IP. I have also used the primer pump to bleed air through the open WVO return line (it's normally looped)and this seemed to draw a fairly good flow of SVO. Hence, the majority of air should be bled. Yet when I run the engine and switch to WVO, nothing comes out of the open return line and the car stalls within 10 seconds. Crazy thing is, a few days ago I had the car running on WVO with the looped return line open. The return SVO just kind of dribbled out, but the car ran on WVO for a few minutes. When I reconnected the looped return, air must have entered the system and it has not run on WVO since. :mad:

you may want to install a electric fuel pump at the tank. you can get one for about $30. I have the same system as you and thats what i had to do. i also have a 16 plate heat exchanger works good . Rick

Rick, where did you get the electric fuel pump, and what is the PSI rating?

I got it at the local parts store Shucks . I`ll check it out better tommorrow i couldn`t`see very well out there tonight and i don`t remember the brand or PSI i think it is 7 PSI .I know one that is used is the Facet posi-flo EFP-3 4-7 psi you can see one at www.frybrid.com.

Boost Pump
 

I have a walbro marine boost pump. It works great and came with my first kit and I have not been able to find them anywhere. Napa sells 4 types of posi flow pumps in several different gph and psi ratings. I have found a better pump made by Mallory but have not been able to find a Canadian source for these yet. I can't find the part numbers for the napa pumps but try searching for fuel pumps at www.napaonline.com

Will
www.veggiefuelsystems.ca

Purge mode will pull fuel from the diesel tank, run it through the engine and return the extra to the veggie tank. The primary benefit of this is NOT to thin the veg oil, but to push diesel fuel through the veg side of the system thereby eliminating all air in the system between the point of the loop and the veg tank.

Personally, I would purge the system for a good 3-5 minutes. Turn off the engine, switch it over to veg mode with the ignition on (so that the valve is open) then manually bleed the lift pump to remove the air between the point of the looped return and the lift pump. Flip it back over to diesel mode. Start the engine and then switch over to veg mode when you reach operating temps.

I would definitely try the above before putting in a secondary fuel pump.

The only way I know of to test for leaks in the system is to pressurize it with a bike pump or low psi air compressor and then spray soapy water on each connection: bubbles = leak. Of course, you have to pinch off the hose just before the fuel tank.

I might also suggest you pick up a copy of Veg My Ride. Sounds like you have the IDENTICAL car and nearly the same equipment featured in the video.

Good luck!
Marc

I do not have a WVO/SVO setup, yet, but I have heard of problems with the Pollack valve failing and sticking partially open.

Check the pollack valve while you are at it.

You made no mention of the filter for the WVO, but you did mention filters for diesel. Are you filtering the WVO before it gets to the lift pump?