WVO leaking into diesel tank - PeachParts Mercedes-Benz Forum

plantsmoveme · #1 08-01-2013, 12:40 AM

After install my ground was not neutral when the lights were turned on. This resulted in a backflow of veggie oil into the diesel tank. A more appropriate ground was established, electrical issues seem to be worked out, but now I'm still seeing the original fuel gauge slowly moving up after running a lot of veg oil through.

I believe as a result I have had gunk come loose in my tank, have had to clean filters more frequently, and am about to clean out the fuel tank. I am wondering if maybe some of that gunk has gotten into the valve and is preventing full closure. Is this a reasonable possibility to examine, or should I start elsewhere?

Also can anyone send me to a good source related to chasing down vacuum leaks with a mityvac? I think I have several, but most obvious is the dreaded door lock and engine kill symptoms.

Thanks in advance

grease lightnig · #2 08-01-2013, 02:34 AM

Did you block off the return bolt on top of the factory diesel fuel filter? First rule of Mercedes conversion.

If not take said bolt out of the car and wash and dry it real good (I use a blow torch) Then fill it with JB Quick Weld. Set it with the bolt side up to harden and if you over filled it drill out the holes in the top after it dries. You just want the bottom center section filled. Do not get the JB weld on the bolt threads.

psaboic · #3 08-01-2013, 09:29 AM

If you have the return lines going to each individual tank (diesel back to diesel and wvo back to wvo), two separate switching valves (one for fuel supply and one for fuel return) along with two separate switches for each valve, you shouldn't need to fill to bolt, correct?? Granted you may get a little cross-contamination when you purge, but not a whole lot. If I am wrong, someone please correct me.

grease lightnig · #4 08-01-2013, 09:36 AM

Anything going into the engine is now being returned to the diesel tank the longer you drive the more it is filling the diesel tank via the bolt. The bolt has to be filled the problem will go away.

If you want to flush into the diesel tank the veggie that is in the lines then the fuel selector switch only has two positions on and off. When you switch the veg off and the diesel on the veg in the lines gets pushed back to the diesel tank.

GregMN · #5 08-01-2013, 02:48 PM

Quote:

Originally Posted by psaboic

... you shouldn't need to fill to bolt, correct?? ...

Incorrect.

psaboic · #6 08-01-2013, 11:48 PM

Quote:

Originally Posted by GregMN

Incorrect.

Please explain why! I would like to understand why the bottom of the bolt needs to be filled if you are isolating the two fuel systems by the dual switching valves.

Thanks,

Glenn

grease lightnig · #7 08-02-2013, 12:37 AM

Take the Bolt out and look at it. You are not isolating the bolt. The IP and the Injectors lines both return the fuel to the diesel fuel filter via the banjo bolt mounted on top of the diesel fuel filter. It does this because the bolt is hollow and the fuel gets pushed into the diesel fuel filter and this is connected to the diesel tank.

plantsmoveme · #8 08-02-2013, 12:51 AM

I was somewhat involved with the install and don't remember any banjo bolt being filled. I'll ask my friend who helped install it. Thanks.

psaboic · #9 08-02-2013, 01:35 AM

So if you use a solid bolt, or fill in just the bottom of the banjo bolt with JB Weld, that doesn't that completely take the spin on filter out of the system?

Or does filling in the bolt only prevent return fuel from going thru the spin on fuel filter but still allows supply fuel from the IP to flow thru the spin on filter?

Again, correct me if I am wrong.

Thanks,

Glenn

grease lightnig · #10 08-02-2013, 08:35 AM

3 bolts are attached to the factory filter. The input (1) the Output (2) Both are mounted on the side. And the Return (3) The return is mounted on the top of the filter and has a three headed banjo on it. The return flows around the bolt when it is filled and flows in and around the bolt from the factory.

psaboic · #11 08-02-2013, 10:59 AM

Gotcha! Thanks for the explanation! I will be filling the bottom hole (and just the bottom hole) of that bolt with JB weld once I finish up the two-tank conversion I am helping out on.

oldsinner111 · #12 08-06-2013, 07:43 AM

what I did,was remove cigar hose to return line,attach one end to short hose,and hook to return line.The other might have attached a foot long hose,using a 3 way attach to fuel line giong into primary filter.This way I looped the fuel while on veggie.Results hotter fuel,no diesel contamination.when switching back to diesel I closed the loop.