A little background: This noise seems to have appeared after I changed the engine (rotella synthetic 5w-40) and transmission oil (motorcraft synthetic). It comes on at about 2500 rpm and stays there until I can't hear it over the engine noise. It seems like it may have gotten worse over the last week. Tonight I will try to get an audio clip.

This morning before work I was under the hood and slowly brought the rpm up and hear a sound like "tinktinktink" but in very rapid succession and high pitched. It seems to be coming from somewhere between the back of the engine and in the bell housing. I searched for an hour last night looking for people with same noise, but no one had anything that sounded like this. I'm concerned that something is about to break. Car seems to run fine. Trans does have small leak or two that appears to be coming from the seals at the connection points on the trans. I( I need to clean it up to be sure) , but its only a drop or two a day.

 

It's probably your HLAs.

 

Would the lash adjusters make a sound that appears to originate from the bellhousing? I'm familiar with a lifter tick, but this is like a tinktinktink or pingpingping. If ping/knock didn't sound like rocks in the engine, I would think that this is what people hear when they say their engine is pinging. The sound sort of rings from the bellhousing.

I know my description is lousy, hopefully a real sound clip will help

 

Braineack, my camera did an excellent job of isolating all of the negative noise under the hood. I've located the vacuum leak that you can hear at the exhaust manifold. The pinging I was referring to can be easily heard. you can hear it really well at 24s, 30s, 37s,43s, and 48s - 55s I think you were right to begin with. Heres link:

YouTube - Engine noise