I have a 2000 dodge caravan 3.0L. I have a bad rattling noise coming from my air intake plenum, or so it would appear. I poked around with a 2 foot extension while pressing the other end to my ear and everything else sounds good. No noise from the valve covers or the block itself, nor from the timing belt area, catalytic converter is new. I have no clue what this could possibly be, or mean. When i start the van it rattles alot in the air intake plenum and when i rev the engine it goes away until it idles back down, then it starts again. The rattle is sparattic, it has no pattern at all, i really cant describe the actual rattle sound at all, but that its sorta like theres a bolt inside the plenum just bouncing around like crazy. Any help would be great, as i am not sitting good with cash at this point.

Actually after just checking, it does do it when reving the engine but you just dont notice it because its not as loud and its happening much faster while reving engine. Also want to clarify that its not a pinging sound. Also it seems to quiet down as the engine warms up, but it doesnt really go away. With my ghetto stethescope i have determined that it does not seem to make any noise where the air intake meets with the engine block er whatever, it just seems to be under the very top part that sits highest on the engine. I am contemplating pulling that top pan er plate or whatever off to see if i can see anything out of place but i have no clue what is under there. Is there anything under there? or is it just an empty space where air flows through? maybe there is a gremlin hiding in there trying to drive me nuts? Did we ever hunt down and kill all the gremlins left over from our world war with the germans? lol

I believe its actually the upper air intake manifold sorry im not an advanced car worker onner guy at any rate its the air intake that sits right on top of the engine.

 

I would remove the upper pleunm and inspect.

 

You mean the whole thing right down to the block or we talking just about the rectangular plate part that sits up on top, also what would i be looking for exactly? I have no clue what could be inside of that thing that could be banging around like that. this link is to the part im talking about, its a different year but still the same. Someones selling it on ebay it might not be up long. http://cgi.ebay.com/ebaymotors/ws/eB...category=36474 sorry for my nubness

 

The upper pleunm is bolted to the intake manifold. You just to remove the upper part and find your rattle sound.

 

Will do as soon as possible and ill get back on with my rersults. Thank You

 

I'm not sure how much this applies but I also have a supercharged Bonneville with a fender well intake system which doesn't suppress the intake noise as a factory system does. When it's cold, it also sounds like there are marbles rattling around. It only lasts in a noticeable way for a couple of minutes and then gets substantially quieter as it warms up. I was told on the Bonneville forum I go to that what I'm hearing is related to the idle air circuit.
It's possible that what you're hearing is normal to some degree, especially if you've made any changes to the air intake.

 

nah there have not been any changes made to initiate such a noise and what it is doing is very far from normal. Its not a low quiet rattle, its fairly loud and sounds more like a chunk of metal bouncing/flopping around inside rather than a marble rattle sound. It does quiet down alot though after it warms up a bit, and doesnt really make the sound once the car is put into gear as much. Ive noticed that when i start it up and its making the noise, if i turn the wheel it get louder and more violent sounding.