Will a faulty rear main seal cause an internal leak (causing the engine to blow smoke through the exhaust). I had it bad for a while and last week i replaced the intake valve stem seals and it calmed down, but it is still smoking.

 

No, the rear main seal keeps oil from exiting the crankcase/oil pan to the outside of the truck. It doesn't connect to the combustion chamber at all.

If you did the valve seals correctly, you're down to piston rings or plenum gasket. My money's on the plenum.

 

+1 on the plenum gasket leaking.

 

i did it aleady but im not sure if i did it right again, i accidently tightened it to 18 ft lbs, i tried to take the pan of again but the pan was really stuck (im going to check it again in a little bit).

 

18ft/lbs. hopefully hasn't split the intake or possibly block but overtorquing is a BIG no no!

Take the TB off and look for pooling oil in the intake.

 

BTW, please tell me it wasn't 18 ft/lbs on the tiny pan bolts...

 

yes it was 18 ft lbs, and i checked and no there is no oil.

 

OUCH! that's supposed to be 84 in/lbs Bubba! I'm amazed it took that much.

 

That pretty much leaves the rings as the culprit. You could try running some cleaner through the engine to see if it clears up. That would be way cheaper than rebuilding the engine. If you had any cylinders that we fouled up with carbon deposits and such then it might be what is burning off but not super likely. The cleaner is still cheaper in the long run.

 

Could it be his heads are going out?