Acceptably Safe Soot Levels: Can Anyone Speak with Authority? - Page 3 - PeachParts Mercedes-Benz Forum

shertex · #31 12-17-2010, 09:53 PM

Quote:

Originally Posted by layback40

I am surprised that no one has jumped in with the origin of this "spec". After your other thread yesterday, I spoke with my contact at CAT, His view was that if I was happy to do a motor rebuild at 8~10,000 hrs, then go for the higher soot limit. I am aiming for 20,000hrs on the motors without a rebuild.
The higher levels of lead in your oil at higher soot levels shows higher bearing ware rates. The bulk of the white metal forms a "mud" in the bottom of the sump as it settles.

Actually, the lead levels were absolutely identical (as you can see on the analysis itself that I posted elsewhere)....this was an oversight on the part of the guy in the lab. The only wear metal that showed increase was iron....neither he nor I knows what that indicates.

layback40 · #32 12-17-2010, 09:58 PM

Have you found the MB spec that says 2% ? I have had a quick look & not found it.

shertex · #33 12-17-2010, 10:13 PM

Quote:

Originally Posted by layback40

Have you found the MB spec that says 2% ? I have had a quick look & not found it.

Not yet...poked around owner's manual and FSM and didn't find anything. May well be a mistaken recollection on my part.

Does this sound familiar to anyone?

babymog · #34 12-17-2010, 10:28 PM

I've perused the 603 manual, and the FSM, and owner's manual and at this point found no reference to soot loading limits. Ran into a lot of other useful engine info I had forgotten, but nothing regarding oil changes other than the 5000mile recommended change interval for normal use / normal oil.

shertex · #35 12-17-2010, 10:30 PM

The only thing I've been able to find are various references to Marshall Booth's claiming that it was an MB spec....but of course that doesn't take us to the source.

babymog · #36 12-17-2010, 10:39 PM

Hmm, so the 2% might not be M-B recommended? I'm getting my life-jacket on, ... might be abandoning ship on this one!

What is the Moh's hardness on the soot particulate? Anyone know?

layback40 · #37 12-17-2010, 10:49 PM

Quote:

Originally Posted by babymog

Hmm, so the 2% might not be M-B recommended? I'm getting my life-jacket on, ... might be abandoning ship on this one!

What is the Moh's hardness on the soot particulate? Anyone know?

I think you may already be on a sunk ship.

Hardness varies a lot. it can be much harder than most metals, not as hard as diamond though.

babymog · #38 12-17-2010, 10:59 PM

Don't call it yet, Shertex might still find that 2% source to bail the ship.

I've never really investigated the makeup and hardness of diesel soot, would really be interesting to find out how hard it is and other abrasiveness characteristics. It doesn't seems to erode the turbo impeller at any high rate plus soot is re-introduced in the intake without filtration (EGR), seems that if it was tremendously abrasive (like me) it would cause problems in both areas. Just thinking with my keyboard.

If hardness and abrasiveness isn't the issue, then I am left wondering what is?

TheDon · #39 12-17-2010, 11:27 PM

I miss laying soot with my SDL

layback40 · #40 12-18-2010, 01:41 AM

Quote:

Originally Posted by babymog

Don't call it yet, Shertex might still find that 2% source to bail the ship.

I've never really investigated the makeup and hardness of diesel soot, would really be interesting to find out how hard it is and other abrasiveness characteristics. It doesn't seems to erode the turbo impeller at any high rate plus soot is re-introduced in the intake without filtration (EGR), seems that if it was tremendously abrasive (like me) it would cause problems in both areas. Just thinking with my keyboard.

If hardness and abrasiveness isn't the issue, then I am left wondering what is?

Soot has a structure like 3 dimensional chicken wire, its not like graphite, nor diamond, its 1/2 way between. If the particles are big enough, there is a problem. They need to be way smaller than the bearing clearances. If not the bearing becomes like a miniature rock crusher without hard surfaces. The rod & main shells soon get eaten away. The cam/followers & rings/bore also get torn up as they run with no clearance.
The other problem is that it causes the oil to appear as though it has a higher viscosity but when sheared it shows it has a low viscosity. Bad in a cold motor.

MTUpower · #41 12-18-2010, 07:15 AM

A bypass oil filter will take care of soot. What is your favorite bypass oil filter?

shertex · #42 12-18-2010, 09:37 AM

Well, you good folks have instilled enough doubt and fear in me that I was out this morning in 20F changing the oil!

#43 12-18-2010, 09:47 AM

Quote:

Originally Posted by shertex

Well, you good folks have instilled enough doubt and fear in me that I was out this morning in 20F changing the oil!

LOL, that wasn't the intention. I do think that it makes the most sense to stay close to the manufaturers recommendations unless you have a very good reason to change. I am a mechanical engineer, but I'm not a materials or lubrication specialist, and I don't pretend to know enough about oil chemistry to "overrule" the manufacturer. Oil changes are relatively cheap and easy (unless you do them in 20F weather).