strange power loss on WVO - PeachParts Mercedes-Benz Forum

odie · #1 11-03-2004, 11:23 AM

I've been running a 50% WVO blend for a couple weeks now and have noticed a strange pattern of power loss

In short as the fuel tank level drops, power drops off noticably. As soon as I add fuel engine performance instantly returns.

Each time this cycle repeats, the power loss occurs at a slightly higher fuel tank level reading. Now it happens just below the 1/2 tank mark.

It appears that switching back to 100% diesel has a minimal effect on the power loss cycle. At best it seems to push back the power loss to a lower tank level but it still occurs.

My current theory is that the veggie oil is cleaning the fuel system and 20+ years of tank gunk is coming loose and starting to clog the system

By refilling the fuel tank, I increase the fuel pressure against the tank screen to help push fuel through until the fuel level drops and pressure drops with it. Also as fuel level drops the IP can't suck enough fuel through the filters either as the tank pressure pushing the fuel forward drops.

I bought the car a couple months ago. I have NOT yet changed either fuel filter or check the tank stainer. My plan was to run a few weeks with the blend and them change the filter after the expected tank cleaning the veggie oil will do. 200K on the car. The car ran super strong when I bought it and continues to run strong on a full tank of 50% veggie.

I hope to make it to the weekend before pulling the strainer and filters this Saturday.

Any bets as to what I will find???

Old300D · #2 11-03-2004, 12:13 PM

Sounds like you are checking the right things. How are you pre-filtering the WVO? What is your ambient temperature?

P.E.Haiges · #3 11-03-2004, 12:28 PM

odie,

First check the strainer in the tank by removing the fuel hose where it is connected to the the steel fuel line. If the fuel doesn't come out in a steady stream, the strainer is clogged. Do with this with the tank almost empty.

If the strainer appears to be clogged, drain all the fuel out of the tank and remove the strainer for inspection. If the strainer appears top have a brown silicon like substance on it, you have a fungus problem. Only way to cure fungus problem is to use a Biocide like Biobor.

If you get a steady stream, the strainer is OK. Then check the inline fuel filter next. Take it off and blow into the output connection. If you detect much of a resistance, replace the filter. If the problem still exists, replace the main filter.

P E H

odie · #4 11-03-2004, 12:40 PM

two stage filtering. Using industrial sock filters. 25 micron and 5 micron. I let the oil settle a day or two if it's murky. Some of my collected oil is pretty clear and it goes into the filters right away.

My first 35 gallon batch of veggie I also dumped a gallon of used motor oil into the filtering drum. I will say that the used oil does not stay mixed very long. I'm on the last of my original WVO/motor oil batch. The dispensing drum had a good sludge layer of used 5 micron filtered motor oil in the bottom when I pumped the last of the veggie out and into the car. But I assume any of the used motor oil that made it to the fuel tank settles to the bottom of the fuel tank and is picked up first, washed out with the diesel I add to the tank and mostly burned up by now. Yes it's kinda gooy but the diesel should have thined it out and flowed it right thru the tank screen and fuel filters and burn most of it. Everytime I stopp the motor oil should start settling and thus be the first to get burned up everytime. Thus it's "purged" from the system prety quick.

Ambient day-night temp range has been 70-95 for the last few weeks. A cold front came thru on Monday and dropped it to 50-70. But the car still starts and runs fine in the cold morning. Half way to work it started slowing down again. I pulled over and put 2-3 gal diesel in the tank (spare car in the car) and I was back up to full speed again.

For almost all this pattern, temps have been very summerish. The car has ZERO mods for veggie oil.

Does anyone care to put forth a "vote" for what they think the cause is or what I may discover when I pull the strainer? Kinda like the Heraldo RIvera "Al Capone's vault" thing.

odie · #5 11-03-2004, 12:45 PM

Hmmm, I was going to go straight for the strainer this Sat. But I think I will do that fuel hose first and see how fast/slow the fuel comes out first.

BTW, the tank will be kinda full because the car seems to run ok the fuller the tank is.

BTW, this excersise should be for anyone having similar problems, not just WVO users. I believe this is a symptom of restricted fuel flow. I'll know Sat. Until then I'll keep driving and watch how the power loss/return pattern continues.

phidauex · #6 11-03-2004, 01:27 PM

Sounds like restricted fuel flow to me! I'd check your filters. Veggie oil will tend to clog filters sooner than diesel, simply because waste oil still has some particulate matter (5 micron filters only remove 'most' of the 5 micron particles), and because it can dislodge other gunk collected elsewhere.

I'm gonna bet your filters are clogged, since the symptoms are very similar to what we experience on my friend's long-range veggie bus. When the filters begin to clog, power is lost. You can feel it happen, and know you need to change the filters soon.

Many WVO enthusiasts install fuel pressure gauges above and below the fuel filters, and compare the values. As the pressure rises above the filter and drops below the filter, your filter is becoming saturated. You can just watch the gauges and change your filters just before you get enough differential to cause a problem. Its the same technique used for industrial filtration systems. Monitor your pressure, and extrapolate your filter load.

Your prefiltering sounds good. The smaller you can filter the better, but letting it settle for a few days will prevent loading your filters, making them last longer and work faster.

I'd say check those filters and strainers, and get back to us.

Peace,
sam

odie · #7 11-03-2004, 03:35 PM

stupid question...what tool is used to remove the tank strainer?

hex or square? what size?

coachgeo · #8 11-04-2004, 12:44 AM

Quote:

Originally Posted by odie

stupid question...what tool is used to remove the tank strainer?

hex or square? what size?

Giant monkey wrench or other simular too. Matters though what diesel you have. I think a wagen tank's strainer is different than a sedan for example.

JamesStein · #9 11-04-2004, 09:07 AM

My wifes 300D has a similar problem. Although its rigged with a 2 tank setup. On WVO it acts like its choking at anything higher then 60mph. I think either the primer pump is leaking and it leaks worse with the added stress of sucking the oil from the tank, or the lift pump itself is bad.

Speaking of the lift pump. I can't seem to find one on Fastlane or anywhere else for that matter. Or is the "primer assembly" actually what is known as the lift pump?

odie · #10 11-04-2004, 10:39 AM

The car is still running strong on a full tank. It was about 50' F this morning and the car started and ran down the highway fine. The tank is mostly all diesel right now. Just three more 45 mile commutes until Sat morning. I can hardly wait. It's kinda like that just before christmas feeling. Waiting with anticipation as I open up my tank screen and filters and see what the WVO elves have left me.

BTW, on the wagons, is the tank screen that round plug looking thing in the center bottom of the tank? That has been my guess. I looks like the fuel outlet line is in the front of the tank, about an inch or two up from the bottom, which I found to be a little strange. I would have thought the fuel outlet to ba at the bottom and coming straight off the tank strainer.

lietuviai · #11 11-04-2004, 11:01 AM

It's problems like this that make me hestitate to make the conversion to WVO. It was 30 degrees this morning when I left the house and it took quite some time for the car to warm up while driving it today and I'm running dino diesel. I wonder what trouble I would have had with WVO at such a low temp?

whunter · #12 11-04-2004, 11:16 AM

You admit the car is used?
You have not replaced the fuel filters.
You do not know what the PO was running for fuel.
You have no idea of fuel filter age.

You are going to start diagnosis at the fuel tank screen?

Why?

Suggest you install a new secondary filter, before you take a bath in fuel.

I have a neighbor, eight blocks away, 1983 300D, he runs 70% used motor oil with 30% used hydraulic oil to thin it down, all free from the plant where works, his filters plug up every 2 - 3 months.

If you don't know what the PO ran for fuel, change the secondary filter, then you have a base line to start from.

odie · #13 11-04-2004, 02:24 PM

why?...going to start at the fuel souce and work forward and see what is clogged and what is clear. Even if just changing the filter solves the problem, I will still what to pull the strainer and see what's going on in the tank.

Plus, as you point out, I have done nothing with the car yet. I plan to replace both filters and check/clean the strainer anyway. If for no other reason than to have new filters for a fresh start because the current filter age is unknown. Then I will have a good base line.

I just bought the car a couple months ago. New trans filter, air filter, oil change, adjusted valves, turbo swap (car had wrong turbo, CA style).

I had just been waiting to run some WVO and letting all the crud get flushed out into the filters before changing them.

I'm guessing that's exactly what happened.

rwthomas1 · #14 11-04-2004, 06:20 PM

I think that one of the biggest problems with running WVO is the sharing of fuel system parts. Stock filters were never intended to have WVO run through them so they get restricted quickly and impede flow. Running a blend has mixed results because there are too many variables. How viscous is the oil? Is it hot enough? Thoroughly dewatered? etc. Straighten out the car first then start messing with veggie. RT

odie · #15 11-05-2004, 10:27 AM

How many microns is diesel filtered to when you buy it at the pump?

What is the micron rating of the fuel filter on the car?

The car ran home fine and back to work again fine. So far 150 miles after the fill up and running strong. I predict it will loose power again on the way home as the tank level will be down 7-8 gallons from full.

Can't wait for Sat morning. Filter changes and strainer cleaning. I love experiments