The car is a 94 Nissan Sentra, just picked it up from a junk yard as a fixer upper... when I start the car and it's idling, it sounds like a diesel truck, it's making some noise inside the valve cover almost, we pulled it and didn't see anything that could possibly be wrong

what's your thoughts?

we thought the timing chain could be lose...

 

valve lash

 

what is that???? never heard of it??

 

vlave lash is teh amount of freeplay the valve has from the lobe of the cam. when excessive, can cause noise. piston slap will make it diesel like sonding.

 

whats the fix for something like this? is it a timing issue?

 

or a rod knocking....................................

 

Or really REALLY bad detonation.

 

its definately not a rod knocking

any other ideas?

 

Go with what has been said already? What are you looking for? Loud noise from the head is usually attributed to the valves in some way? Adjust them and report back!