buzzing sound at low rpm

[jd1828af]

my car has a buzzing sound at low rpm. but it goes away when turbo builds any boost. a friend said it has something to do with the turbo and it is similar the the sound a semi makes at low rpms. he says its normal. is this really normal, i had a grand am with a turbo and i dont remember it sounding like that. what is the cause of it?

 

[1gTURD]

One problem i had was the balance shafts. pop your timing cover off and check ur timing belt and the balancer shaft belt... the rear balance shaft (oil pump shaft) tends to throw the "bearing" and the shaft rides inside the bearing and maks a buzzing noise like holding a pen in a fan or s omething liek that. If this is the case, check www.vfaq.com for the balance shaft removal setup and replace the timing belt and all that fun stuff

 

[jd1828af]

if that was it wouldnt it make this noise all the time and not just at low rpms

 

[jd1828af]

i got some more info on this.

the sound comes from the valve cover/ timing belt area. i only hear it betweeen 1500 and 3000 rpms but not at idle and not at anything over 3000. i talked to a guy that says that about half of all the dsm he has seen make this noise.