Primary filter melted by biodiesel? - PeachParts Mercedes-Benz Forum

Jeremy5848 · #1 02-14-2008, 01:11 AM

As a B100 biodiesel user I naturally keep a close eye on my fuel filters and started to notice awhile ago that the primary in the '87 300D was looking strange. Today I decided to be safe and change it even though it has been on for less than a year and did not appear dirty. As you can see from the photos, the inside white plastic framework (holds the filter screen material) is warped, as if the biodiesel has softened the material of which it is made. I'm sure it was not that way when I installed it. The outer clear plastic part of the filter is undamaged and it did not leak.

I don't know the brand of the filter -- I tend to buy a few filters at a time as part of a larger order and don't know where this one came from. The only marks on the plastic are a directional arrow and a symbol that looks like a crown with three points (or a letter "W" in a box). Anyone recognize that?

The filter had only a little crud in it -- the black specks in picture #3 show the fuel from the filter, dumped into a cup. If the filter had not been internally melting I probably would have left it alone.

While changing the filter, I also discovered that the hose from the fuel heater to the lift pump was starting to melt and drip (at the lift pump end). The 4th picture compares the damaged end to new fuel hose. So I changed it too. Always a good idea to check everything once in a while and someday I'll learn to do that.

Let that be a lesson to you!

Jeremy

whunter · #2 02-14-2008, 01:24 AM

Where do you fill up?
Others may need to know...
It could be a bad filter or chemical contamination of the fuel.

#3 02-14-2008, 02:02 AM

Too much methanol?

greasybenz · #4 02-14-2008, 02:07 AM

Ill take a pic of my filter that has only gotten diesel since ive changed it. It looks EXACTLY the same. Dont think it has anything to do with the bio.

probear · #5 02-14-2008, 02:44 AM

Well, from what I can tell, 4219G is not the proper hose for your car. It is made of nitrile which will break down from Biodiesel's solvent properties. 4219G is normally used for Oil, gasoline and gasohol, but not for Bio-diesel. You need to get hoses that are made from Viton. Nitrile hoses were typically used prior to 1993, and will eventually break down from Bio-Diesel. Nowhere can I find 4219G recommended for diesel applications.
The fuel filter could have the same problem. If it was originally a gasoline filter, BioDiesel could easily destroy it.

Jordan G · #6 02-14-2008, 07:04 AM

Quote:

Originally Posted by probear

Well, from what I can tell, 4219G is not the proper hose for your car. It is made of nitrile which will break down from Biodiesel's solvent properties. 4219G is normally used for Oil, gasoline and gasohol, but not for Bio-diesel. You need to get hoses that are made from Viton. Nitrile hoses were typically used prior to 1993, and will eventually break down from Bio-Diesel. Nowhere can I find 4219G recommended for diesel applications.
The fuel filter could have the same problem. If it was originally a gasoline filter, BioDiesel could easily destroy it.

Good point - but he didn't implicitly say he used that new hose stamped with 4219G on his car - merely used as a comparison in the photo.

I'm sure though, that the prefilter is for diesel.....but it's very interesting how it melted/deformed like that.

NC Benz · #7 02-14-2008, 07:44 AM

Quote:

Originally Posted by Jordan G

Good point - but he didn't implicitly say he used that new hose stamped with 4219G on his car - merely used as a comparison in the photo.

I'm sure though, that the prefilter is for diesel.....but it's very interesting how it melted/deformed like that.

I am slow, but I do catch up.... just to make sure.... in your first picture, the end to the right is going to the IP, correct?

To me, it just looks like the fuel filter buckled under fuel pressure. As cheap as these filters are, would that be any big shock?

Your fuel line... I dunno about that one. I didnt see if you said what kind of line it was.

C Sean Watts · #8 02-14-2008, 07:53 AM

Quote:

Originally Posted by ForcedInduction

Too much methanol?

Especially if the filter is made of any plastic other than high density polyethylene. I have nothing personal against developing nations, but I would not try to save a $ with "Made in Taiwan, China, etc."

Jeremy5848 · #9 02-14-2008, 11:01 AM

The biodiesel has always been commercial, not homemade -- no methanol, from various suppliers. AFAIK, it comes from the midwest, dragged here in tank cars pulled by diesel locomotives. Not as green as I would like but we live in an imperfect world, alas.

The fuel hose I grabbed for the photo was just something from my junk box.

Fuel flow through the filter is towards the bent end. Looking at it now, it does indeed look as if the inner part was collapsed a bit as the lift pump tried to suck it up.

Jeremy

pawoSD · #10 02-14-2008, 11:26 AM

I don't think the lift pump could generate enough suction to collapse the inside of a filter.....it also doesn't make sense because that could only happen if the intake screen in the filter was plugged and not allowing fuel through....which it wasn't.

LilTimmy · #11 02-14-2008, 12:18 PM

There shouldn't be ANY methanol in finished biodiesel unless it was homebrewed and not washed. The hose looks fairly typical for b100 use with old rubber. I just get replacement hose from the local parts store or MBUSA, it handles the fuel just fine.

italian_diesel · #12 02-14-2008, 04:05 PM

actually, train transport is becoming increasingly GREEN...my friend works as an engineer. They're slowly planning a huge take-over of the trucking business. So your biodiesel might be greener than you thought Jeremy5848!

As for the mutated fuel filter, I'm no expert, but I do run a van on grease. All I can say is that the warning I hear time and time again when you run on grease is to make sure you have the right hoses as the veggie oil can corrode some cheaper hoses and fuel line parts.

Hope it helps.

winmutt · #13 02-14-2008, 04:31 PM

Quote:

Originally Posted by ForcedInduction

Too much methanol?

Too much Meth is always bad.

Jordan G · #14 02-14-2008, 04:40 PM

Quote:

Originally Posted by winmutt

Too much Meth is always bad.

True dat. My teeth are gone and my prefilter's are warped.

Diesel Dan · #15 02-14-2008, 08:52 PM

I've been using translucent polyurethane tubing to run my B100. It's been holding up well for the past year now, while other hose I bought new at the auto parts store has begun to degrade. It also allows me to see if there is any air in the lines.