Help With Knocking Under Engine Area

[5.4ever]

My 99 slaps/knocks/ticks when I start it. This only recently happened. Once it warms up it doesnt knock anymore but when I rev it up it sounds like it does. Its a 32v with 118k miles on it. I CANNOT hear the knock from under hood and engine area, only under the car. It sounds like its coming from the pulleys or even tranny. Any help would be appreciated. Thanks

 

[trombonedemon]

mods?

 

[5.4ever]

Basic bolt ons, xpipe magnaflows k&n intake, and I believe a tune. No pulleys, no cam, nothing extreme... I added a quart of oil(it was low) low its an the max line, and it silence it at start up but once it warms up you can hear it slightly under the car, if I open the hood, you cant hear anything. Would it have anything to do with using 5-20w oil and it having nealry 120k? Thanks

 

[trombonedemon]

With info you gave its kinda hard to say, could be normal, might not be. I have a rebuilt top and bottom end and the engine does what yours does from time to time. Check your spark plugs for starters to see if the plugs are backing out.

 

[trombonedemon]

Oh forged pistons make racket until the warm up. Are you the original owner and how long has the sypmtoms been. Might be worth putting the original tune in to see if conditions persist.