Recently, I hear some rattling noise coming from the front when I am going up hill with the engine doing around 4000rpm.

I opened the hood and nothing seems coming loose.
Any idea what this is?

 

i seem to have the same problem. but it all the time, engine cold or hot, whenever i'm going upward or rolling on the street.

When the engine hits 4000rpm the rattle start and go off as the engine goes under 4000 rpm.

seems like a rusted exaust shield, or maybe something related to the vics system.

 

how is your idle? i used to get a little rattle noise from under the hood if i launched from 2nd gear (for wet roads or rolling stops) and the rpm would drop a bit and make a rattle. i would also on occasion have a slight dip in RPM while idle. the other day i replaced the original PCV valve for the heck of it and the rattle went away.

my guess is the PCV valve was soaked in oil which made it harder for the gasses to push the metal valve inside the plastic housing. this caused the rattle (the sound of the valve flapping up and down). at least thats my hypothesis.

luckily the PCV valve is cheap enough (local part store had it for $5 US) to try and if it didn't help it still wont break the bank.

 

my engine has the same rattle from 4k-5k when heading towards redline. Sounds like something is loose. I keep doing it so whatever is it will work it's way loose.