[Vndin]

Okay guys, just want to get some opinions before i get too far into this myself. Im driving my 06 zx4 st (2.3) home from columbus ohio last weekend and I start hearing a noise from the engine bay. To me it sounded kinda like a heat shield vibrating. I pulled over and as it sat there and ran i heard nothing. flashlight in hand i looked everything over and under the car and it all looked nice, no vibration or sounds at all.
I get back in the car an continue on my way thinking maybe i was letting my imagination get to me but then I hear it again. I pull of the highway and to a local parts store where I again look the car over... it looks fine, i check the oil and it shows that its a bit low. (maybe a quart) so I top off the oil. I notice this time while stopped if I rev the engine, once the car gets into higher rpms. (3 to 4k) the sound reappears. I get the car home and look it over, oil hasnt changed since I filled it so its not pouring out or anything but everytime I rev the engine up there is the noise.
it sounds like it's on top of the engine right under the valve cover on the exhaust side of the head (far right side of the engine nearest the trans). Im figuring perhaps it burnt a lifter. I havnt been able to check into it yet just wanted to pick your all's brains.
Im confident that its on the top end (as Ive heard many cars with rodknock and it doesnt sound anything like what Im experiencing), just wondering if anyone had a similar situation.? The car is VERY clean so its not something I just want to beat the hell out of till it dies.
Thoughts?

 

[hEaT]

I'd look at the header heatshield which isn't far away from where you're describing the noise. I can't recall if there are any baffles in the valve cover that could come loose. I had that issue on a Lima which sounded similar to rod knock.

 

[jrj90620]

I had to replace a bad motor mount on my 2.3L forcus.If it's bad,could cause engine to move and touch something else.

 

[Vndin]

had a chance to look into the car a bit, took the valve cover off and examined the lifters, valves, and springs (after removing the exhaust cam) that all being said, the lifters do show some wear but nothing that looks out of the ordinary. I was considering swapping out the lifters just to try it but cannot seem to find the info that Im looking for.

my lifters, exhaust side, range from thicknesses as follows:
342, 342, 402, 422, 462, 462, 402, 382
(numbers all stamped on the underside of the lifter bucket.)
I cannot seem to find them for sale anywhere, unless im just overlooking them. I see sets of lifters, but I wouldnt think that they would all be the same (each engine) so i wouldnt think you can just buy a set. any thoughts?
dont know that it'd even fix the issue, just tossing ideas around because I cannot seem to find anything else out of place. actually debated on just buying a motor because i dont really have the time to tear the head and engine down, I can swap the motor in a matter of a day.