My duramax usually strong with no hesitation, recently it has started lagging between shift 1-2 sometimes 2-3 when I'm accelerating fast. I have to let off the throttle, it changes and then continues on as normal. I was checking under the hood for anything loose and found this oil/soot on the motor, haven't ever seen it there before and engine is otherwise spotless. How could this get on the outside of the motor, can't find any leaks. Checked the fuel filter bleeder screw as some posts said may cause hesitation, it was tight, filter has about 3k miles on it. Any suggestions on the problem and if I need to do anything about that oit?

Is your egr blocked?

Change the fuel filter to cure the shifting issues.

The dirt sticking to the intake is completely unrelated. It is oil seeping out of the joints in the intake which got there by way of the PCV system, causing dust and dirt to stick. It is not soot.

Change the fuel filter to cure the shifting issues.

The dirt sticking to the intake is completely unrelated. It is oil seeping out of the joints in the intake which got there by way of the PCV system, causing dust and dirt to stick. It is not soot.

This is what I would do, as well.

That black my friend is not normal for the truck, especially where it is. You need to get it in for service very soon. The oil and such that comes from the PCV goes no where near where you got it, so no, that is not normal.

Go to dealer and get checked.

I was thinking first was a leak in the boost llines but i agree no where near there. Defiantly needs looked at.

Brian

That black my friend is not normal for the truck, especially where it is. You need to get it in for service very soon. The oil and such that comes from the PCV goes no where near where you got it, so no, that is not normal.

Go to dealer and get checked.

Thats actually the very first point that the EGR enters the intake, looks like its leaking pretty good and probably at high boost it leaks enough to cause a hesitation.

Blew the same seal myself. Dealer said it was from having the egr bllocked.

Blew the same seal myself. Dealer said it was from having the egr bllocked.

Pull the blocker before you go to the dealer! And I might be wrong, but wouldn't that side of the EGR - the non exhaust side of the EGR system not have that much pressure? And if it did have enough pressure on that side to blow a flange-gasket seal, wouldn't it be a lot cleaner than that? I agree though, it doesn't look like it's right... after you replace the fuel filter, let us know if the shifting improves.

I don't have my EGR blocked. I will replace my fuel filter this week and see if things improve with the shifting. I have my PPE set on 3 (90 hp), I may drop it down one and see if it still shifts the same way.

The leak is where the boosted air enters the pre-heater.There is a joint or fitting leaking there that usually will not show the signs of oil from the PVC.This needs to be addressed soon as a small amount of boost is being lost by the leak.Oil from the PVC generally shows up where the boost tubes are connected with the blue flex boots and also down stream of the pre-heater where there is an o-ring in the charge tube but will also show up at any point the charged air is escaping.

I would also add that shifting problems can also be addresses by changing the spin on tranny filter. Change it every 5,000 miles like clockwork and that will make sure that it is flowing properly.

A friend of mine bought an LMM and he had 7,500 miles on it and he changed the filter at 4,000 miles. He asked me one day if this winter fuel would make it shift hard and such, and I said no, the fuel onlu gets less mileage and sometimes makes the truck feel sluggish, but the tranny filter not flowing at peak will make it shift hard, so he changed it and the problem was solved.

The leak is where the boosted air enters the pre-heater.There is a joint or fitting leaking there that usually will not show the signs of oil from the PVC.This needs to be addressed soon as a small amount of boost is being lost by the leak.Oil from the PVC generally shows up where the boost tubes are connected with the blue flex boots and also down stream of the pre-heater where there is an o-ring in the charge tube but will also show up at any point the charged air is escaping.

I had this, and went straight to the dealer... said it was nothing to worry about.