When my truck is just running, the engine makes this sowing machine factory noise. It gets worse once the Rpm raises. It started happening after I ran the engine a bit dry of oil. Filled it up and it hasn't gone away. Any ideas? Thank you

 

Any idea

 

what do you mean when you say "a bit dry of oil" ...?

Was the engine completely out of oil? or just a quart or two low?

From your description a large number of things could be wrong...

If you ran the truck without oil then you've likely damaged something inside of the engine, and again this could be a million and half different things.

I've heard this sound alot of the time when one of the exhaust manifold bolts come loose, or snaps off causing an exhaust leak.

So get under the truck and look for black carbon deposits around the exhaust manifold...

That is the easiest place to start... if you cannot find an exhaust leak then I would go ahead and get a compression test done on your engine just to make sure you didn't spin a bearing, crack a piston, bust a valve, etc.

 

what is the oil pressure now, is it in spec, and how does it run now as compared to before. You may have simply collapsed a lifter-----but you could be on your way to a spun bearing. I think I'd check the most obvious things first, like weird color on the plugs, sudden change in mpg/power delivery. stuff like that