Intake pushing air out at idle / howl at speed

**BitterCoalSpitter** · 05-22-2019

Started hearing an exhaust sound tapping my intake cover doing a post trip inspection on the truck. Popped the cover off and slid a sheet of paper under the lid. At idle in park it was blowing the paper up, not sucking it down.. Not sure if that matters but it gets better..

I was hearing a howl and that got louder after turbo lag ( higher rpm around 50 -60 mph). This was coupled with a decent vibration that permeated the cab.

The sound was like I had put a beefy set of MTs on my truck and they were just humming.

But I dont have aggressive tread, and typically it's a quiet smooth ride.

I dont know if it's a hub, the turbo, transfer case, or maybe even an exhaust valve. Something isnt right with this truck and it's really got me stumped.

No codes, boost fine, trans temp sitting between 111 and 128, engine temp around 202, 2012 6.7 with egr delete, and a turbo back.

I fill at a high traffic pilot, and use Lucas oil fuel additive at every fill up.

Thoughts?

1 Comment(s)

**RamIt** · 05-22-2019

@BitterCoalSpitter what are you monitoring PIDs with?

MM3?

0 Comment(s)

**BitterCoalSpitter** · 05-22-2019

I dont have any type of parameter monitoring system yet. Just stock basics.

0 Comment(s)

**RamIt** · 05-22-2019

Does it sound like the exhaust brake is on?

Is there oil in the intake tract anywhere?

There's only a handful of reasons why air would be blowing backwards out the intake; however, knowing that the truck is driveable makes this even more interesting.

0 Comment(s)

**DIESELWRKS** · 05-25-2019

when you did your full delete. do you still have the crankcase hose connected to the turbo? if you have block off plates for the delete check to see if soot is around the plates. if they are leaking. I have heard many exhaust leaks and they all can sound diff. higher speed and rpm you will hear them more.
also have you ever heard your engine fan come on. those things are loud and scare people thinking something Is broke . can have a vib sound. 202 engine temp. is that at idle? I you are concerned on the intake. (airbox) pull it apart. check the filter out. if it a stock air tube. check the tube baffles see if anything is not cracked or blocking. pull the tube off the turbo face and check to see what it looks like. the transfer case, have you checked fluid level. put it in 4 wheel and check it out.. Hubs normally will not have those symptoms. they will be noisy at low speeds and at times when turning. what does your drive shafts look like front and back. dry/rusty or a light amount of grease everywhere.

0 Comment(s)

**BitterCoalSpitter** · 06-01-2019

202 engine temp normal operating. Warm/ran.

I replaced the driver side front u joint and hub assembly. There was a little play there only. Hopped in the truck thinking it might have been a baring, and the sound was still there.

I'm thinking it might be rear diff now. The opinion shouldn't be bad, but that Howel sound is common when the differential is low or the fluid is dirty. Got some Valvoline 75-90 gonna pull it off and clean everything up with brake cleaner. Fill it up and see if my howel is gone..

0 Comment(s)

**DIESELWRKS** · 06-01-2019

So I asked some questions on my prior reply. What do the u-joints look like on the driveshaft. You said you feel vibration. Is the vib at higher speed and rpm’s? where do you feel this when you are driving. Your feet on the floor, your hands on the steering wheel, you butt in the seat. is your truck a long bed or short bed. Check the joints on the drive shafts and carrier bearing if you have a long bed.

Is the howl a constant or do you think the sound is something cyclic, like revolving?

Does the howl sound metallic at all? Have you ever changed u-joints in the shafts. How many miles on the truck and last time you changed fluids in diff

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