WVO woes - PeachParts Mercedes-Benz Forum

lietuviai · #1 07-21-2005, 11:17 AM

See my posts in my cavitation thread: http://www.peachparts.com/shopforum/alternative-fuels/128989-cavitation-possible-air-bubbles-wvo-post936416.html

stockdad · #2 07-21-2005, 11:51 AM

I'm confused as to why you felt it necessary to post this thread, essentially, twice.
Not being a jerk-just curious.

lietuviai · #3 07-21-2005, 03:12 PM

The other thread started as a different subject and evolved into actual problems with my system which seem to have no relation to the cavitation issue. I wanted to attract members with some knowledge of WVO systems without reposting the same questions.
I'm having what appears to be fuel delivery problems and surging issues when trying to accellerate.

TonyFromWestOz · #4 07-22-2005, 04:21 AM

Quote:

Originally Posted by lietuviai

The other thread started as a different subject and evolved into actual problems with my system which seem to have no relation to the cavitation issue. I wanted to attract members with some knowledge of WVO systems without reposting the same questions.
I'm having what appears to be fuel delivery problems and surging issues when trying to accellerate.

I have an OM617 in which I use UCO (Used Cooking Oil) as my main fuel.
I do not believe that any air will be in the UCO if it is heated to 60-80°C prior to the fuel filter.
The symptoms you describe are usually caused by lack of fuel, due to blocked filter, cold UCO and/or other fuel line restriction. If a significant suction is caused, air ingress will cause further issues and will result in the engine missing more and more, until it stalls.

I hope this has helped you.

coldwar · #5 07-22-2005, 10:56 AM

I would like to know more about the symptoms of cavitation that might occur when driving. The previous thread showed this action as collapsing air bubbles- would this sudden explosion of a bubble produce an audible knock, or "crack" from the engine?

I'm still obviously worried about the cracking / pinging noises (similar to spark knock) I'm getting when running near straight Diesel. When I add more WVO, the noises go away when engine heats up, but is very severe when cold- also lots of bluish white smoke at cold idle. With straight Diesel, it's the opposite- no abnormal noises when cold, and less cold smoke, but the cracking noises become very severe when warmed up and the car is at speed. This started well before I started using WVO, but has definately gotten worse.

A Diesel-Purge cured the problem for about a day. I now add "Gunk Diesel Fuel Conditioner" to fuel as directed on the bottle- about a pint per tank full. It seems to work better than the Purge did, but still doesn't eliminate the cracking noise completely.

I am going to leave my car with a good indie in Halifax sometime in the next three weeks- I want him to check the following

-bench test the injectors, replace with rebuilts if necessary
-while injectors are out- compression test and examine pre-chambers
-check fuel vacuum with some WVO in the mix- cold and hot
-adjust valves
-check IP timing and timing chain - adjust and replace if needed.

I have no other symptoms- milage is still 25 MPG or better- no power loss, etc

Dave M.
Sackville NB Canada
1976 300D

ykobayashi · #6 07-22-2005, 11:04 AM

Hi,

Read this:

Why bother with making biodiesel yourself?

Yup, your thread about how easy this was.

You've just hit the knee in the learning curve on WVO. It is deceptively easy, and like other aspects of our diesels, you would never know until you get hit head on with a problem (like I thought 61X engines indestructable till my 300TD started to smoke).

Most likely there is a clog in your system. These happen at the filters. If you've used a conventional tank, check to see if it has a screen on the pickup, these can get clogged. You probably aren't getting "cavitation" but rather you have a clog plus a small leak somewhere.

Crack your line at a number of places and pull on it with a mity vac (with gauge) to get an idea of where the problem is located.

Everytime I start getting confident that I understand this WVO thing I get broadsided with some grungy oil, a leaky filter, water, fry ash or a stuck valve.

Good luck,
Yoko

lietuviai · #7 07-22-2005, 10:30 PM

I don't have any symptoms when switching back to diesel. I use the same filters for both systems with no visible debris in the small plastic filter. In fact up until recently, I was runing the same clear little filter and it wasn't clogged when I changed it after driving on WVO for over 700 miles.
I have notice some wetness around the Pollack fuel diverter so I'm suspecting it may be failing and maybe the cause of my woes. I'm not 100% convinced its to blame since there are no problems running diesel. Also I've started the car on cold WVO before when the car was running good and it started OK and had no stumbling problems at that time.

lietuviai · #8 08-01-2005, 10:57 AM

I went through the entire system this weekend. I found a few areas that were suspect to kinking so I put sleeves on those areas. Overall there were no restrictions. The diverter checked out OK. I also changed my hose clamps to the fuel injector type. I even shrink heated the lines on all the connections to ensure a good seal. It all seemed fine when I let it sit and idle for about half an hour to check for leaks. So this morning I took it to work and @#$!, it did it again. It stumbled under load. I even had trouble keeping it over 50 on a level road. I was constantly switching between the two tanks until I just said "f" it and ran on dino the rest of the way. My only guess at this point is that the IP just isn't up to snuf to pull WVO through 3/8" ID lines.
Is there some kind of booster pump I can use to get the WVO to the IP?
How about modding the IP lift pump?

Matt SD300 · #9 08-01-2005, 11:41 AM

1. CHANGE your spin on fuel filter.

2. Install a Carter 5-7 psi electric fuel pump at the rear of your car. They cost about $70.00.

Habanero · #10 08-01-2005, 11:54 AM

I prefer facet pumps. Much cheaper (35 at Napa for the 5-7 psi model), and terribly reliable. I have had one on my oil furnace pumping for months at a time with no problem. Just ticks away. Larger sizes are available at JCWhitney for a little more money.

As to your problem, do you have a vacuum/pressure gauge on your system yet? That should be the first thing you do. It is much more difficult to diagnose what is going on without it. They are cheap at surpluscenter.com.

I'm a little confused by your statement about the IP having enough suction. The IP shouldn't have to provide suction, the lift pump should do the work. The MB lift pump is plenty strong enough to pull oil through those lines. My original conversion set up used the stock lift pump and it would pull up to 20 inches Hg vacuum when the filter would get clogged. Now I have the gauge right at the IP inlet and when I turn off the Facet pump, it will pull down to about 10 inches Hg and start running out of fuel. Not knowing the exact layout of your system, either you have a blocked line somewhere, filter is plugged, or you aren't using a lift pump. Any one of those will cause the symptoms you describe.

lietuviai · #11 08-01-2005, 05:15 PM

Quote:

Originally Posted by Habanero

I prefer facet pumps. Much cheaper (35 at Napa for the 5-7 psi model), and terribly reliable. I have had one on my oil furnace pumping for months at a time with no problem. Just ticks away. Larger sizes are available at JCWhitney for a little more money.

As to your problem, do you have a vacuum/pressure gauge on your system yet? That should be the first thing you do. It is much more difficult to diagnose what is going on without it. They are cheap at surpluscenter.com.

I'm a little confused by your statement about the IP having enough suction. The IP shouldn't have to provide suction, the lift pump should do the work. The MB lift pump is plenty strong enough to pull oil through those lines. My original conversion set up used the stock lift pump and it would pull up to 20 inches Hg vacuum when the filter would get clogged. Now I have the gauge right at the IP inlet and when I turn off the Facet pump, it will pull down to about 10 inches Hg and start running out of fuel. Not knowing the exact layout of your system, either you have a blocked line somewhere, filter is plugged, or you aren't using a lift pump. Any one of those will cause the symptoms you describe.

I do have a vac gauge but I haven't used it to figure out what's going on. I didn't change the spin on filter yet thinking that if it runs fine while running dino it is a filter. I've been really thorough in looking for kinks or obstructins in the lines and there aren't any.
The only other place that could be causing any restrictions is the in line fuel heater. It drops down to the same diameter as the stock fuel lines. I really doubt that's the problem since I would have had the problem right in the beginning. I'll change the spin on filter for the heck of it to see if it helps.

Matt SD300 · #12 08-01-2005, 09:01 PM

CHANGE YOUR SPIN ON FUEL FILTER... IT'S CLOGGED

Your Diesel fuel is "MUCH THINNER" than veggie oil, thats why it still runs on Diesel.

Just do it and you wont have to type about this problem any more!!

Legal Eagle · #13 08-01-2005, 09:47 PM

This may sound a bit dumb but is your vegie tank vented ? Otherwise what is happening is that there is a vaccum being created and sucking fuel back towards the tank.
I have a Facet 2 1/2-4 1/2psi pump at the fuel outlet port.
http://www.jcwhitney.com/autoparts/ItemBrowse/c-10101/s-10101/p-100000213122/mediaCode-ZX/appId-100000213122/Pr-p_CATENTRY_ID:100000213122
Also you could be experiencing filter blockage or another possibility is water in the vegie. Did you dewater it or are you certain it doesn't have any ? How and to what degree is the vegie filtered?
I cold filter in filter bags to 5 microns after that the restaurant does a pre-filter on it. It contains no water and very little tallow, most of which stays in the bags or on the bottom of my vegie storage drum and I pump from the top 2 inches only.

lietuviai · #14 08-02-2005, 11:31 AM

Yep, it was my spin on filter. I changed it last night and today I was running on the freeway ahead of the packs. I have never experienced a clogged filter in a diesel before and I have over 150K miles in driving experience in diesels alone. I admit that I've only had about 30K miles driving a MB diesel and only less than a 1k miles running WVO. It's definately a learning curve to go through. I'm embarassed and I'll admit it. I do realize that my WVO is a little thicker than diesel but I didn't think it would have made such a big difference. Now I know.
I'm ready to have my crow now.

I didn't add any extra filters to my system but now I'm planning on adding one on the WVO tank. Any suggestions? I'd like a cleanable one like I remember having on a gasser many years ago. I wish I still had it. I was one of those glass type that when you unscrewed the ends the element could be removed and washed out.
Legal Eagle, Yes my tank is vented. I made sure of that when my first symptoms started.

Habanero · #15 08-02-2005, 01:06 PM

It probably won't be the last clogged filter you encounter. Even the best prefiltering scheme sometimes has short comings. That is the virtue of a pressure/vacuum gauge after the filter. You will see the pressure slowly dropping and eventually the vacuum building. At that point you change the filter and go on about your way.

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