2001 5.9 cummins. I have a thumping noise in the air breather. valve clearance is adjusted properly. cant find a leaking intake valve. disconnected cac pipe at intake horn and have noise there as well. engine runs strong . no miss detected. please help if you have any ideas.

 

Im assuming the "thumping" goes up with increased rpms? What mods do you have on your engine? I have a BHAF in an Afe CAI kit. I have a bit of a thumping sound also and its more pronounced when decelerating. The sound comes through my air filter. I never heard it when I had my stock air box. I think it sounds kinda cool. Assuming its a thumping and not a knock...........I wouldnt worry about it. BTW welcome to DB.

 

Is it a thump or a pop?? popping is bad and thumping is normal. does it sound like it's thumping on every cylinder?? diesel take in gobs of air and it tends to make a thumping noise when the turbo isn't prodcing boost, a free flowing air filter will definately make it more noticeable

 

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