Well, i bought a 6.2L diesel truck not running, with plans to swap in a motor i know already works. I then decided to try and first start the motor that is currently in it. It turned out to be fairly easy ( a glow plug problem, which i was caused by a cut wire). Although i did have a bad case of irony. Once it started, the first thing i hear is loud clunking noises. At first i thought that the engine was blown. I then saw a Wd-40 cap fly in the air, and i immediately shut the truck off. Anyway it turns out a wd-40 can which was sitting on the front of the truck fell in between the rad fan and rad, and long story short... I needed to put in a new radiator and fan. Now that i have it fixed again and running, i have a question. It seems to blow blueish-white smoke even when warm up when the engine gets to the higher end of it's RPM range. What could this be? I am going to change the oil tommorow, and see if it helps, but is the motor just worn??

I had the same thing happen to me. Couple things to check:
are you losing coolant?
are you losing oil?

You could have a bad injector, or timing could be off, or potentially the IP could be going out,

Or worst case scenario you could have a crack in your cylinder walls somewhere.

what does the smoke smell like?

how the can of wd 40 get in place to fall"?

Well, i haven't checked to see what the smoke smells like but i will tomorrow. Also, could a to much advanced or retarded IP cause this smoke? And as for the WD-40, it must have been right on the edge and fell in because of the shaking of the engine.

WD 40 can is a whole lot easier to clean up then the muskrat that went through mine. Doh!

Well, i changed the oil, and it seems to smoke less, but it still smokes. It doesn't seem to be losing coolant, though I noticed that the oil level dropped a little right before i changed it. I am assuming the drop was caused by the oil burning, and that there is a slow leak at the back of the motor (which i am assuming is a rear main seal leak). As for the smell, it smells like burning oil, and a hint of something else.

Wonder how long the truck sat not running? Even mine does some strange stuff (shakes/leaks) if I leave it parked for longer than a couple of weeks...
Sounds like you're on the right track with the oil change, I'm no expert but driving it for a week or two should tell you if these problems are the result of wear vs. dried-up seals and such.

Well, i talked to a heavy duty diesel mechanic, and from the description i told him (pump being advanced a whole lot, engine only having 213thousand kilometers, equal blue smoke from both sides, and only at higher revs) he said it was probably the injection pump. Of coarse i forgot to ask him how a bad injection pump can cause blue smoke. So, do any of you guys know how it could cause blue smoke? i have thought really hard about it and can't come up with a reasonable explanation.

Bump... Does anyone here know?

Blue smoke aat high rpm on a gas engine is an indication of worn rings. It could just have sat so long that oil seeped down past the valve seals and into the combustion chamber. Ive got a 350 gasser thats just totally worn out. It burns oil on take off, and at high rpm (the worn rings) and now that the transmission is bad it sits for months at a time without getting started and when i do start it it smokes like hell for a while. I can move it around, it just has no 2nd gear. I tell you what the smoke really rolls out of that thing for a while.. then its ok again. If this is the case with your 6.2 then it probably needs rebuilt, or for sure needs valve seals.

My sub will pop on cylinder or two for about3 - 5 sec if I get on cold. It also blows a little smoke at high rev's even when warm, it's 6.2 NA. It looks blue from a distance but I know it's fuel. Is this a little smoke or is it, oh my god my trucks on fire? Have you tried disconnecting the CDR valve, the tuna can? Maybe it's stuck open and pulling oil in at high rev's. How the compression? Smoking diesels are always fun to describe and diagnose by typing. First hand is the best. Maybe take to one or two other mechanics to see what they think, it pays to shop around.

If it was worn rings, from what i see on gas engines, usually one side will burn more than the other, or even just one piston craps out, but with this engine, the smoke is equal on both sides, so a bad ip makes scence, but i don't know how it would cause the engine to burn oil. I also will check to see how bad the blow-by is