i purchased a 2003 3500 6-speed 4x4 196,000mi. i bought the truck at a good price and i expected it would need a few things, but by the time i drove it 400 miles home the underside of the truck was soaked in oil, and there is heavy smoke when you remove the oil cap while idling. i need advice on whether to rebuild engine or look for a long block replacement. from what i read from this forum the rings are gone. is this the case? i have had several cummins trucks, but i have never had any blow-by or engine problems before. any advice would be great thanks.

 

It doesn't take much oil to make a mess.
I'd drive it more and see how much oil it actually is using.

 

Sounds like an injector stuck open. Is your oil level high?

 

Don't forget that a vacuum pump leak in the wacuum circuit will allow the pump to push excess air into crankcase. Test by blocking vacuum hose at vac pump. Immediate loss of blowby will result. A damaged piston will cause a power loss obviouslly, but generally difficult to figure. A dealers scan tool can diagnois the missing cylinder.

 

'03's don't use a vacuum pump.

 

Where did you get the truck? Iowa?
What color is it?

 

i will drive some more and try to monitor how much oil it is using. there isn't any smoke coming from exhaust. truck is dark grey out of michigan

 

Ok, just checking. There was a guy trying to sell a white 03 around here for 7000 because it had bad blow buy and needed rebuilt. THought maybe some one passed it off as good and you ended up with it.

 

you shouldn't have to drive it to see if it is making oil, just check it and see if it is above the full mark. Usually when you have a lot of oil underneath the truck it means that an injector has stuck open and fuel is going by the rings into the crank case causing your oil level to rise. Once it starts getting too full it will start puking it out the blow by tube.

If your oil level isn't high then you may have bad rings.

 

Here's another perspective https://www.dieseltruckresource.com/...d.php?t=230933

 

make sure the oil doesnt smell like diesel, like a previous post said it could be a hung injector.
Make sure youre not leaking the oil from somewhere.. verify it is coming from the breather. Some is normal especially on the newer ones where its all routed differently. Maybe jerry-rig a puke bottle to see just how much oil there is?
The real acid test would be a compression reading via the injector holes in the block. Would probably cost a few hundred bucks in labor to do. =(