Excessive black smoke from diesels means ????

My 06 Duramax will smoke like crazy sometimes.... usually if it's just been idling or sitting in traffic for awhile and then I get on it hard. btw, I'm totally stock @ 130K miles.

With that many miles, though, I'd pass. Just too many high dollar things can happen.... not necessarily related to the smoke. Injectors, head gasket and turbo will each run you ballpark 4-6K and at 300K miles that truck it due for something. Of course there are numerous other things that could go wrong to.

IMO, at some point you're buying more of a liability than an asset. Say you pay 10K and in the next two years one of those big 3 goes out (pretty likely IMO). So, now you're 15K into the truck. What can you by with 15K now instead of 10K? Probably something with A LOT less miles.

When I was in mile high Denver for a summer season, my Dodge Cummins started to smoke so bad I took it in fearing injectors were bad. Took it to an independent shop, they found nothing wrong (a "stealer" would have claimed the injectors needed to be replaced). Once I returned to sea level the smoke stopped.....and I always heard that elevation made no difference to a diesel. And the engine was chipped at 20K, I now have just shy of 200K, with no issues, and the original injectors....that said, I too would suggest looking for a truck with less than 300K miles.

Regards
Gemstone

Is it just smoking during turbo spooling delay or all the time? I nail mine from a stop it will blow a puff of black smoke then quit.

Private party sale?......ask the owner what tuner he is running

Car lot sale?........have then run diagnostic and see what tuner is being run

300,000 would be a "no deal" for me. Just the mileage alone, trany, rear-end, etc.

Too much fuel. Dirty or clogged air filter. Injectors faulty or too large for the turbo/air mixture, Chip, or a failing turbo, big $$$ to fix.
I thing with 300,000 miles, i would shop elsewhere, say thanks, but no thanks.

injectors....

It could be low turbo boost also, but black smoke is more fuel than the engine can burn. The engine probably has a chip or tuner program in it. 300K miles is up there, these things last pretty good but they don't run forever.

Brian

The truck probably was or is chipped and IMO is not one to play with. It has been run hard and out away wet to many times for my taste.

Black smoke equals over fueling. I suspect the PO has done the deletes and run the heck out of it. There are many others out there in better condition for you.