Engine/Transmission (1998.5 - 2002) thumping noise coming from the air breather

[HookMeUp]

I get home from work today and here what sounds like an exhaust leak coming from under the hood. But it's coming from the AFE air filter, you can hear a constant thumping noise, it apperars to go away when when you bring the engine speed up, what is it?

 

[LMcCary]

Possibly a valve or valve spring that is broken.

 

[JeffWhite]

I'm taking it you've had the AFE for a while and this noise is something new?

My BHAF lets some odd sounds through at idle, but it has always been that way.

Lots more clatter and maybe something you could call thumping too. I take it this

(on mine anyway) is normal but am wondering when this started for you?

 

[Cowboy Medic]

I had a similar episode about a year ago. Got to looking and I had lost one of the manifold bolts. Replaced it and the thumping was gone.

 

[HookMeUp]

I'm taking it you've had the AFE for a while and this noise is something new?

My BHAF lets some odd sounds through at idle, but it has always been that way.

Lots more clatter and maybe something you could call thumping too. I take it this

(on mine anyway) is normal but am wondering when this started for you?

Just started today,or noticed today. I would hope it's not a valve! I would think there would be other noises with that!

 

[fox]

Set the lifters or have them set. One or more is out of tolerance.

 

[HookMeUp]

Stopped by the local dealer today and asked one of the techs about the noise. He said it was normal, you just don't notice it with the stock air box on. He explained it like this, as the turbo is spinning the blades will grab a scoop of air, and that is the sound you are hearing. You will notice it more depending on weather, temperature, humitidy, air density, etc ... made sense to be. Well anyway said it was nothing to be concerned about.