Is the white smoke steam or oil vapor? If it's steam, it just needs to warm up, if it's oil vapor it's probably pretty serious. Same with the knocking. It could be timing or it could be a rod bearing or any of a number of potential problems that fall somewhere between the two in severity; it all depends on what it sounds like.
need a new engine most likely. driving dry or on low oil for a few miles will cause that..it will be cheaper for you to just get a used engine with lower miles from a junk yard than taking it apart and rebuilding it..
what engine?
No.
Cause low pressure oil pump
When the fuel in an engine cylinder ignites prematurely or unevenly to cause power fluctuations and a "knocking" sound. usually occurs when an engine is very how or improperly timed.
Engine knocking can be caused by numerous things. Having the incorrect spark plugs, carbon deposits on the cylinder walls, and being low on engine oil may all cause a knocking sound.
Having a bad rod bearing could cause a truck to make a loud knocking noise and shake when driving at high speeds. The engine having a coolant leak or an engine timing problem could also cause the knocking noise.
Bad bearing or rod
can you elaborate? engine noise? stationary/moving? ticking, tapping or a definite knocking?
Yes, fouled spark plugs can cause engine shaking, and loss or power. I'm not sure about knocking but I'd guess that too.
engine coolant getting into an engine cylinder from a bad head gasket , cracked or warped head
Crank Shaft.