Could be caused by bad lifter, bad pushrod, bad rocker arm, bent valve, or if the sound is heard deep down, it might be worse. Either way, the valve covers need to come off for inspection.
what engine?
No.
Cause low pressure oil pump
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..
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.
can you elaborate? engine noise? stationary/moving? ticking, tapping or a definite knocking?
Bad bearing or rod
Yes, fouled spark plugs can cause engine shaking, and loss or power. I'm not sure about knocking but I'd guess that too.
A bad harmonic balancer can cause a knocking noise. The harmonic balancer doesn't actually produce the noise, but it can cause the noise in the engine.
Crank Shaft.