2006 , 215000 mi
Truck idles bad, smokes & burns oil, fuel mileage is bad.also smoke from crank case vent pipe. Had injectors cleaned 6 mo. Ago. Seems to run ok on highway. Any thoughts?
Thanks

 

Chances are you've got major issues actually related to injector issues or computer problems that initiated the problem.

A common problem with these trucks is fuel not spraying when and where it should, if it fires at the wrong time, the burning fuel will sear the cylinders, which causes scoring, which causes oil leakage past the rings.
The results are 2 fold, loss of compression and and excessive blowby.
Adding insult to injury, as the scoring causes compression loss, it also slows fuel burning and now you have raw fuel dumping into a cylinder, which mixes with oil and gets pumped out raw (or partially burned) from the exhaust.

The reason it "Seems to run ok on the highway" is simple, higher RPMS allow less time for compression leakage and allows the fuel to burn.

In some very severe computer glitch (or injector failure) cases, certain injectors actually can be locked or held open, dumping raw fuel to the point it'll actually hydro-lock the cylinder and tear up the crank.
If enough raw fuel is dumped into the cylinder in a short time, it can "put the fire out" in that cylinder and wash the cylinder down also scoring it.

One word of free advice, if a Commonrail acts like it's fueling funny, dropping cylinders at idle, or excessive smoke at idle, or gets "hard to start" STOP DRIVING IT.

By all means DO NOT idle them longer than it takes to cool the turbo or, in cold weather, to get heat from the vents on a cold morning.

I cannot stress enough DO NOT LET THEM IDLE FOR EXTENDED PERIODS!

If you tear it down, count on at least needing pistons, a re-bore and a set of injectors.
I also wouldn't be surprised if the turbo is junk from rings passing through the turbine, which is a very good sign of cylinder damage and actually how I have diagnosed potentially major cylinder damage.

Mark.

 

Sounds very similar to the symptoms my truck was exhibiting; it's in the shop now. In my case: 3 injectors needed the internals replaced (tips were all good); #3 cylinder needs new oil & compression rings and the cylinder wall needs a slight honing to remove a small scratch. Just as a precaution we're having the head checked and will be replacing the main & rod bearings. I was fortunate that I shut it down soon after the symptoms showed up or I'd probably be looking at a lot more damage and a lot more repair costs.