oily soot deposits

[Diesel Dimwit]

When I removed the turbo manifold on my recently acquired '05 LLY to drill & tap for a boost gauge fitting, there was a significant buildup of oily soot sludge. A little might be expected from EGR, but this seems excessive. I believe the truck is stock except for 4" cat back exhaust. Helpful advice would be appreciated.

[Mark Rinker]

Was the truck previously running a programmer?

[DmaxMaverick]

It's normal to find some oil residue in the intake, caused by the closed circuit crankcase breather. Early LB7 Duramax engines have the vent to atmosphere, but yours has the vent dump into the intake, before the turbo. The EGR doesn't help, but it's not the cause.

Much depends on what you mean by significant buildup, but some is normal. Periodic cleaning won't hurt anything, but usually not required. Some folks have toyed with an oil vapor condenser inline with the vent, and that won't hurt, either.

[Diesel Dimwit]

Thanks for the responses. Mark, its interesting that you asked about a programer. I believe the prior owner had a Bully Dog Power Pup. I don't know at what level he ran it. Is this significant?

[Kennedy]

EGR is pure evil...

[Mark Rinker]

It could be.

If the original owner ran a tune that produced alot of soot and had a heavy foot, the resulting fuel laden blowby could have caused the sooting you are seeing.

I suspect my '06 would look similar if opened up. The original owner ran a Superchips tuner with multiple levels, and by the looks of the tires at 30K, had 'experimented' enough to scrub off 3/4 of the factory set already! (He towed a large, heavy hay hauling trailer, so some of the accelerated tire wear is to be expected.)

Curiously, there are oily, sooty streaks on the outside of the pressurized air charge tube from the intercooler, right at the intake connection. Must expand the tube enough to leak, but not blow the clamp off. I have been watching it and its not getting any worse - i suspect it was from some heavy towing, with a heavy foot, on a #3 level setting by the previous owner. Otherwise, it would be getting worse now - we are running bone stock and establishing a performance baseline over 20K miles or so before any modifications.

As was stated previously, if there is soot being produced by combusiton, there is soot getting past the rings into the crankcase, and then soot getting sucked back through into the intake.

"Adding additional fuel to a diesel engine without adding additional air has two dramatically negative effects. First, by dumping fuel into a diesel without the appropriate amount of air to go along with it, a considerable portion of the fuel does not completely combust. This uncombusted fuel is often seen coming out of a diesel’s tailpipe as black, sooty smoke. It’s wasted fuel. What I like to call, “horsepower you can see, but can’t use.” All this smoke contaminates the engine’s oil at a much faster rate than normal. Here’s what happens: Modern engine oils typically contain a chemical which gives the oil its extreme pressure capability. You might call this an “anti-wear agent.” When a massive amount of smoke is present, soot invariably gets past the rings and into the oil, where it binds with the chemical, disabling it. When oil loses its anti-wear agent, internal engine parts wear faster." - from current article by Gale Banks at BanksDiesel.com.

http://www.banksdiesel.com/Tech_bigdensity.cfm