i have a 93 chevy diesel truck it smokes white when in idle it also has blowby and missing, has 190000 on it ,the glow plugs have been chenge to manuel, but when you get on the highway it uns good ???????.

This site is much better suited for your questions:
http://www.dieselplace.com/forum/index.php

Sounds like a head gasket.

Wannabe

e mm i've got a friend that is a desel mec and has one of them. i'll ask him tomarrow and let you know what he said .

had alot of problems with the heads cracking between the valves.

Cracked head....
Those are called "killerdiesels" over here....

Have a 95 just had cracked heads. I went with aftermarket heads that are thicker. You have some things you need to check first. Do a Pressure check on the cooling system. Engine running and engine off. You could have a turbo going bad also but doubt ful since it clears up at speed. Sounds More like you may have a Problem with your fuel system. Aleaking injector or a bad fuel Pump. Will white smoke with a head/headgasket failure or way to much fuel. Since it does clear up and you didnt say it overheats or pushes water out of radiator i would be more inclined to think you have a bad injector. With that much mileage i would Redo the injection pump and injectors if you find a bad injector.

Looking for a rebuildable 454 with all the alt/water, A/c carb etc. Anyone?