I have a Volvo 670 with a ved12 465hp. I'm hearing air either sucking in or escaping when the turbo kicks in and out. Can someone please help me I just purchased the truck.
A charge air cooler test is your first step. A dealer can do it for maybe an hours cost of time. You need to start there.
Check the pipes/boots going to the turbo for cracks or best case a boot is loose and can be tightened back down.
it's not uncommon for them rubber boots to tear open. easy thing to spot. and replace. i drove a pete dump truck with the same problem. don't ask my WHY the driver never wrote it up.