Living with a Greasecar, part 11...chasing down a problem

Yeah, my first issue with running grease, other than the nasty grease spill I had a few years ago is upon me. Just over 81K miles on veggie, 298K on the car to date.
I was experiencing fuel starvation under certain conditions. Under load sometimes, and while turning most of the time. It seemed to happen about 30% of the time when making a left turn, 90% when turning right, the fuel pickup in the tank is on the left side of the tank. My first thought was the dreaded "chicken skin" that I've heard develops inside the fuel tank. It's polymerized oil that forms inside the tank walls, it's a reaction between the oil and oxygen. So, I thought "ah, I have chicken skin in the tank, when I turn a corner to the right it clogs the pickup". Naturally I was patting myself on the back because of my unparalleled brilliance for realizing soo quickly what was wrong (I'm setting myself up here folks). So, a nice Saturday comes (nice for Michigan at least) and I decide to pull the sending unit from the tank to clean out the square feet of nasty chicken skin I'm sure to encounter. What I see is.........

and

No chicken skin inside the tank. In fact, I was blown away by how clean it was, save for a little bi-metal corrosion on the fitting there at the supply side. I mean, 80,000 miles means about 2,600 gallons of used veggie oil! What you are looking at in the picture is the loop of copper pipe that has coolant heated by the engine. The engine pushes it back through that loop and it warms the oil. It works quite well. In the winter, after the temp starts to come up, the radiant heat will clear frost and ice from the back window Ain't no keeping ice cream in the trunk for long.
But what I did see that troubled me was black floaties, though I knew these weren't the reason for my fuel starvation.
This picture is from the right side of the tank, the baffle is visible in the upper left corner of the pic, the coolant loop is on the other side of the baffle.

Here's a shot of the other side of the tank.

Where did these nasties come from? The rubber grommets where the coolant/fuel lines (they are coaxial, fuel inside of the coolant hose) pass through the tank wall. Time to replace those before I have a nasty mess in the trunk.

I cleaned all that crap out of there naturally

So, I start thinking about the fuel starvation issue. I remember reading about a guy that had the Pex fuel line collapsing under load. It confounded him. And I started really dreading the thought of replacing the Pex lines. Then I remembered how I used to tell my students to be sure to check the simple things before jumping into the big repair. I thought maybe the fuel filter might be clogged, but surely that couldn't be the problem. Turning wouldn't have have effect if it were just a clogged fuel filter. I priced out Pex. Then I decided to spring for the $21 fuel filter because it's easier than the Pex lines, and because I really should at least try it before I perform open-greasecar surgery.
Well, the 20 minute, $21 fuel filter fix cured it. What a doofus!
I haven't cut the fuel filter apart, I might just so see what it trapped as a way to evaluate my filtering method further. If anyone is interested, I'll post pics of the filter internals.

Off topic question on grease-cars in general:
I know that you have to start and end on diesel. How long (how many miles) do you run it before you switch to grease, and how far before you get to your destination do you switch back? I'm trying to decide if my commute will be worth it or not.

DrBoost wrote: Well, the 20 minute, $21 fuel filter fix cured it. What a doofus! I haven't cut the fuel filter apart, I might just so see what it trapped as a way to evaluate my filtering method further. If anyone is interested, I'll post pics of the filter internals.

If part of the gasket got into the filter...

On an experimental system we have up north, depending on the oil sand ore they bring in, some of it can have a high (for lack of better description) "charcoal-esque" substance concentration. These relatively light flakes of material get into our analyzer 1/2" stainless lines and get stuck there. They get stuck in such a way that they basically act like a check valve depending on which way we are flowing through the lines.

I'd bet something similiar was happening in your filter. Congrats on the K.I.S.S work around though!

DrBoost wrote: I haven't cut the fuel filter apart, I might just so see what it trapped as a way to evaluate my filtering method further. If anyone is interested, I'll post pics of the filter internals.

I'd like to see it. I've got a buddy who's running WVO, and I'm the one he calls when the thing needs some work. I've managed to teach him regular maintenance and replacing consumables (and also that "car guy" isn't shorthand for "The Enemy"), but the one he bought was already converted. Since he didn't do the conversion himself, I don't know how long his has been running around.

And yeah, his is a Merc W123.

In reply to mtn:

generally, if you a using coolant to heat your fuel in-tank and also have an external coolant heat exchanger, once the vehicle is up to operating temperature you should be fine. you should have a fuel temperature gauge, and you want the fuel to be around 160 degree

mtn wrote: Off topic question on grease-cars in general: I know that you have to start and end on diesel. How long (how many miles) do you run it before you switch to grease, and how far before you get to your destination do you switch back? I'm trying to decide if my commute will be worth it or not.

On a day like today (45 or so in the am when I left the house) I was on diesel for the first 5 or so miles. In the really, really cold winter (I cover the grill) I can go 7 miles, I think I've done 9 once. In the summer, 4 miles is enough. Then I go back to diesel when I'm about a mile from my destination. I don't have a flat plate heat exchanger yet. When I get one, I can shorten that distance just a bit.
How long is your commute?

friedgreencorrado wrote:

DrBoost wrote: I haven't cut the fuel filter apart, I might just so see what it trapped as a way to evaluate my filtering method further. If anyone is interested, I'll post pics of the filter internals.

I'd like to see it. I've got a buddy who's running WVO, and I'm the one he calls when the thing needs some work. I've managed to teach him regular maintenance and replacing consumables (and also that "car guy" isn't shorthand for "The Enemy"), but the one he bought was already converted. Since he didn't do the conversion himself, I don't know how long his has been running around. And yeah, his is a Merc W123.

I'll cut it apart tonight. That filter has about 50K on it, that alone shows I filter my oil well since some guys are only getting 5K out of a filter
How is he filtering his oil? What kit is on it?

Again, as always, I enjoy the Greasecar updates and the general learning experience.

Looks like a trip to the local food hardware supply store is in order. I'm sure it's capable of surviving in waste oil, being that's entirely what it does.

alfadriver wrote: Looks like a trip to the local food hardware supply store is in order. I'm sure it's capable of surviving in waste oil, being that's entirely what it does.

Yeah, I'm not sure why those grommets aren't viton already. They will be soon.

In reply to DrBoost:

Well, I called him up-he sold it last month. He's farming full time now, and decided he'll just use the truck all the time since he doesn't have the commute into town anymore. Seemed like a professional kit (based on quality of materials), I seem to recall it had some kind of inline heater, rather than the flat plate. He can't recall whose kit it was. I'll bet his filtration wasn't as good as yours,though. He couldn't get more than 8-10Kmi. out of a fuel filter.

So, don't feel like you have to do extra work on my account!

EDIT: It must have had something like your heat exchange in the tank, otherwise I don't know how it could pump it cold. Never saw the inside of the beast.

I'm going to cut it open tonight. I want to see what it collected in in 45-50K miles. I'll post pics for any that care.

DrBoost wrote:

mtn wrote: Off topic question on grease-cars in general: I know that you have to start and end on diesel. How long (how many miles) do you run it before you switch to grease, and how far before you get to your destination do you switch back? I'm trying to decide if my commute will be worth it or not.

On a day like today (45 or so in the am when I left the house) I was on diesel for the first 5 or so miles. In the really, really cold winter (I cover the grill) I can go 7 miles, I think I've done 9 once. In the summer, 4 miles is enough. Then I go back to diesel when I'm about a mile from my destination. I don't have a flat plate heat exchanger yet. When I get one, I can shorten that distance just a bit. How long is your commute?

Not long enough to do a conversion--it was 6 miles one way until yesterday when I started my new position--now it is 3 miles one way. When I move next week, it will be less than that.

However, there is a chance that within 6 months I'll be buying a home out in the country (there is currently a deal where first-time home buyers buying a rural home can get a 0-down mortgage)--that would be a minimum 10 mile commute, and likely even farther.

So IF that happens, it looks like it might be worth it if I get the heat exchanger as well.

My gas mercedes is suppossed to have the filter changed every 15k miles so 50k miles on what you are running is amazing!

I thought copper in a veggi oil system was a no-no? Something to do with polymerization?? That black crud is polymer?? Note: I am new to this stuff and I thought my research told me this. I could be totally wrong!!

In reply to benzbaron: The truth is, I should have changed it 5K ago. I think that's when I first noticed the issue. It was subtle enough that I put it off.
In reply to rodrammage: Yeah, copper in a veg system isn't ideal. The alternative (in the heat exchanger) is aluminum. The issue with aluminum is cracking over time due to it's being brittle in comparison. If it cracks you get coolant in your fuel and that'll take out an injection pump pretty quick.
The black stuff you see are bits of the rubber grommets failing. The issue with poly oil (chicken skin) is the oil, on the copper, being exposed to the air. The pic below shows my tank at a very low oil level (less than 1/8th tank)

You can see that the fitting on the right is exposed to air, now, with the tank tilted, look at how clean the fitting on the left is, it's always submerged.

My flat plate head exchanger will be all aluminum for sure though.

Thanks! The oxygen illustration in your tank is quite remarkable. I appreciate you taking the time to explain.

I cut the filter apart and didn't really see anything but dirty paper. I was hoping it was a pleated filter so I could look at the inside of the pleats. The stuff you see on the outside is a result of me cutting the housing open I'm pretty sure.

But I cut the layers of fiber apart and didn't see anything to speak of.