Low Sulfur Fuel Problems? - PeachParts Mercedes-Benz Forum

bops1231 · #1 05-03-2007, 02:32 PM

I've still working my way through a very dirty fuel tank in my '82 240D (190k). The tank has been flushed, strainer replaced, etc. After one tank of fuel, the primary fuel filter was black, so I replaced both the primary and secondary filters. Now I'm getting air locks, and have to bleed the engine to start it.

I think the current problem may be caused by the Napa fuel filter I installed (since I had run out of the German ones). I don't think it is seating properly on the housing.

I just went to a "Black Forest Motors" shop locally, and bought a set of German fuel filters (Mahle KC-22 for the cartridge). In the process, I asked if anyone was having problem with the new low sulfur fuel (<15ppm). "Oh yes, lots more fuel and air leaks. We're doing a lot of work on that these days."

Anyone here experiencing anything like that with the new commercial fuel?

John Bonds
Charleston SC

vstech · #2 05-03-2007, 02:43 PM

search ULSD here, you will find tons of posts about it. most are debunked, but it does hit DV's on the modern ip's. 96 andup... approx.
John

aklim · #3 05-03-2007, 05:19 PM

My 99 E300 and my 01 Powerstroke motor are as yet unaffected

TMAllison · #4 05-03-2007, 06:42 PM

Quote:

Originally Posted by vstech

but it does hit DV's on the modern ip's. 96 andup... approx.
John

In addition to fuel line, pre-filter and shutoff valve o-rings. Basically any older fuel related o-ring is at some risk of drying out.

lkchris · #5 05-03-2007, 07:26 PM

If your seals were old and about to start leaking, ULSD will speed up the process.

bullwinkle · #6 05-03-2007, 08:16 PM

If your secondary filter wasn't sealing you would (should?) have massive fuel leaks there-I'd be looking at fuel lines for wet spots personally, the lift pump should pressurize the secondary filter, only a cracked or severely restricted primary would cause air locking (along with air leaks between the lift pump and the tank).

Biodiesel300TD · #7 05-03-2007, 10:20 PM

If a litttle biodiesel is added to the ULSD the shrinking rubber/leaking problems go away. ULSD shrinks rubber while biodiesel expands rubber. I've gotten a lot of calls at work about VW's leaking after one tank of ULSD. ULSD also has less lubrication properties than the LSD. Again biodiesel added solves that problem as well. It has high lubrication properties. You only need a small percentage, around 5%, of biodiesel for the ill affects of ULSD to go away. If you have biodiesel available I would try that to stop the leaks.

aklim · #8 05-03-2007, 10:30 PM

Quote:

Originally Posted by Biodiesel300TD

ULSD also has less lubrication properties than the LSD.

I thought it was made to LSD standard? IIRC they devised a standard for LSD and said ULSD had to be made to that same standard? If it couldn't, by itself, a lubricant was supposed to be added till it got there.

#9 05-03-2007, 10:35 PM

Quote:

Originally Posted by aklim

I thought it was made to LSD standard? IIRC they devised a standard for LSD and said ULSD had to be made to that same standard? If it couldn't, by itself, a lubricant was supposed to be added till it got there.

True, diesel is still required to meet the same ASTM standard for lubricity at the pump. However, the leakage concerns are valid, especially on old seals.

aklim · #10 05-03-2007, 10:51 PM

Quote:

Originally Posted by Craig

True, diesel is still required to meet the same ASTM standard for lubricity at the pump.

However, the leakage concerns are valid, especially on old seals.

But if that is so then ULSD and LSD will have the same lubricity properties. So do we really need Biodiesel or any of the snake oils out there for lubricity issues? Now if you say a few early batches are not up to snuff for whatever reasons, call it growing pains and they will get to snuff, I might see dumping some additive now and then for that issue but not as a lifelong thing.

They have mentioned that for older seals, it could be a problem and some diesel shops have mentioned it too.

#11 05-03-2007, 10:55 PM

IMHO, we don't "need Biodiesel or any of the snake oils" for anything. The lubricity should be adequate for the IP, and old seals will need to be replaced when/if they leak.

aklim · #12 05-03-2007, 10:58 PM

Quote:

Originally Posted by Craig

IMHO, we don't "need Biodiesel or any of the snake oils" for anything. The lubricity should be adequate for the IP, and old seals will need to be replaced when/if they leak.

I thought the IP was oil lubricated?

TMAllison · #13 05-03-2007, 10:58 PM

As pointed previously, this has been discussed ad naseum.

IIRC per Chevrons article posted previously, rubber components that are old and already prone to failure are adversely affected by the changes in aromatics used in ULSD causing them to shrink and/or lose elasticity to the point of failure.

Slambert · #14 05-07-2007, 05:25 PM

My 250D developed a leak at the top of the IP when I was running ULSD when I was out of Biodiesel. Started using Bio again and it stopped. Ran out Bio started using ULSD.....leaking again, put Bio...leak stops. Something is swelling and strinking those IP seals. I'll eventually replace the seals, but if it aint broke don't fix it.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode