Having an issue with my 06 mega cab 2wd. It has a lot of oil smoke coming out of the crankcase vent hose under the truck. There is little to no oil smoke coming out of the exhaust and no diesel in the oil either when I do an oil change so it does not seem to be getting past the rings. Any ideas what could be causing it?

 

While the engine is running, unscrew the oil fill cap on the top of the engine.
without screwing it back on, place the oil fill cap back in it's hole (loose)
It should simply sit there.
If it doesn't just sit there and is excessively jiggling about from a bunch of "air" blowing out of the oil fill hole, that is bad. Very bad....

 

westcoaster gsve you some good advice, but I am curious about somethings. How do you know that smoke is coming out of the vent? What gives you the idea that this is happening? Is it only when the engine is cold or at operating temps? Is it really oil smoke or could it be just vapor from the cold? Can you see the smoke coming out at idle when you look under the truck? Perhaps most importantly, has your oil consumption increased? In other words, how much oil are you adding between oil changes?

 

Thank you, I will do the oil cap test and see what it does. As for the smoke, I can actually see it coming out of the hose and can smell the oil as well. The oil consumption has increased considerably as well, I have gone from having to add maybe a quart between changes (at the most) to probably 4 quarts between changes

 

Adding 4 quarts of oil between oil changes is indicative of a serious problem. Sorry, not the news you wanted to hear. You never mentioned any smoke out the exhaust, only smoke coming out the vent, so at this point would discount a turbo problem. Perhaps the next step is to get a compression test and go from there.
Let us know what you find.

 

One thing that happens on the common rail engine is an injector sticking "open" (in some form) essentially over fuelling the cylinder. Over fuelling the cylinder causes excessive temperatures.
This causes the piston top to melt and eventually the loss of compression in that cylinder. The compression (as well as any combustion that may take place) that is normally contained in the cylinder by the piston rings, "blows by" the piston rings into the crank case.
That in turn typically causes the excessive blow by and oil consumption you are experiencing.

The simple, inexpensive, DIY tests are in this thread.

As indicated, not the news you want....

 

On the oil cap test, I do not flip it over upside down when I put it sit it on the hole, I leave it rightside up same as if I were screwing it in correct? I will do this along with a compression test but at this point, odds are I am not dealing with a simple vacuum system issue then?

 

Given the minimal information we have so far, it appears that you are heading for piston removal. The results of the compression test will perhaps decide your fate. A leakdown test would also be valuable in this case.

 

There is a procedure to measure blow by with a manometer. Basically using a 3/4 T with a hose barb on one end to fit the vent tube, a plug in the other end with a .302 hole drilled in it, and a small hose barb on the T part to run to the manometer. Warmed up and full power I think it’s supposed to be under 10”h2o. A turbo leak could also pressurize the crankcase and think there is a procedure to isolate that by redirecting the oil return, but if you are seeing blowby at idle (when there’d be no boost) it would probably be fair to assume rings or piston.

if you have access to a scan tool, cylinder contribution would be interesting to look at. Or if you have access to a scope and an amp probe a relative compression test would be non-invasive and quick/easy.

 

This is what you are looking for:
What it should NOT do:

What it should do:

 

Thank you for the feedback. For an update, I did the oil cap test and it looked like the lower video, it did not push the cap off of the oil fill hole, it simply sat there or would vibrate off when the engine was running. There is still a lot of smoke coming out of the vent hose. I had a ‘91 with 330k miles and a ‘99 with 280k miles and both had less than this truck.