I have a 83 300 SD that I burn 80% processed biodiesel. I have gotten rid of the stock air intake system and built my own air intake and oil seperator. Just recently when you get at a constant speed for several minutes you can hear the engine sort of load up slightly and a huge amount of blue/grey smoke will exit the exhaust. You can floor it for just a few seconds and it will clear up and maybe stay clear for 10-15 minutes and do it again. Air intake tract is dry. I vent blowby gasses to the atmosphere. The only thing I can figure is the turbo or the injectors. What do you all think?
Thanks,
Rodney

I don't know what you've done to the system. Could be your improvised setup, or your fuel.

Blue/grey smoke probably means oil, though.

Do a purge, that should clean injectors at least.

Last night I removed the air intake assembly and my oil seperator, and just ran a hose from the valve cover to the fenderwell to vent the blowby. I ran the car like this to see if it would do the same thing, and it did. You can actually feel the engine load up when the smoking starts. You can push the pedal down a bit and it will clear up for a little while until you get to a steady rpm, and it will do it again. As long as you are varying rpm it will not do it. I seem to think that maybe turbo is stalling and I am getting too much fuel. I am going to pull the turbo and injectors and see if I can find anything.
Rodney

before you do that

when was the last time you

a) changed fuel filters
b)adjustsed the ALDA
c)cleaned the banjo bolts
d)checked the turbo for play and ease of spin