Loud air blowing noise under acceleration, duramax

[preston]

Loud air duct blowing noise under mild acceleration. It doesn't do it under all conditions in fact full throttle I usually don't hear it. But under load at lower speeds and throttle positions, kind of sounds like when a big panel truck goes by under load and you hear that huge air rushing noise above the sound of the engine.

Or for example  if you took the air box off a car. I'm not sure if I'm losing power as like I said under full throttle it feels strong, but it might be a little bit soft in these load situations when I hear the noise.

 

First though is obviously a leak somewhere in the charge air system, but what's odd about it is as stated above its not consistent under load. I don't have a boost gauge but I've had enough of them that I have a pretty good idea of what the boost response looks like under driving and there are lots of times I feel it would be making boost but its not making the sound.

And when it does make the sound it doesn't come on gradually its like some dump valve is opneing. Its hard to pinpoint where its coming from other than "engine bay".

 

Its probably a leak of some sort in the charge system. I poked around best I could without taking anything apart.

 I just wanted to make sure there wasn't some "dump valve" being triggered incorrectly or somethin or some other possible cause because the sound just doesn't seem to act like I think a leak would.

[silveradosid]

dont know what year you have but it sounds like the waste gate is stuck on the turbo

[grizzlyltz]

DMax turbo’s use VVT so no dump valve/ waste gate

Almost sounds like your cooling fan is cycling as per your noise description

 

 

 

 

 

 

Grizzly

 

 

 

[Hillwood]

What YEAR is your truck?

Sent from my SM-G965U using Tapatalk

[preston]

Its a 2015 Sierra.

 

Interesting thought about the fan - it does kind of sound like that although its awfully loud not sure the fan at full blast would be that loud over the engine. It would explain the way it seems to come on so strongly ie without any ramping in and out and might explain the randomness of it (although it occurs frequently its not predictable except that I think it only happens under some type of load). Detriments to that theory are though that it seems to have some level of tracking with the engine speed. Not entirely sure though.  I've been noticing it over the last week or so but I need to go out and do some critical driving to see if/how/when I can trigger it, and roll down the windows, back the throttle off etc. 

 

>Dont know what year you have but it sounds like the waste gate is stuck on the turbo

 

Hm, I would agree if you said blow off valve or dump valve. Seems like a wastegate would just reduce boost, not leak air (and if it did leak it would be exhaust noise not blowing air).

 

 

[grizzlyltz]

If this was a turbo vain or a boost leak issue you would get a engine light imo, you might experience lack of power , frequent regen’s , etc

I had a lml and the fan would roar louder than the engine




Grizzlyltz

[preston]

A check engine light is on actually, not sure when it popped up (recently). Truck is new to me so I haven't bought a scan tool yet.

I'd been doing a lot of work to the truck with the battery connected/disconnected so I wasn't putting two and two together as I thought it might be a false alarm - Guess I'll need to grab a scan tool and confirm.

Probably get a code "low charge pressure" - doesn't help me find it though !

[mlance]

Preston, did you ever figure out what was going on with your truck? I have the same model Duramax and I have the same thing happening on mine. It's intermittent and I haven't noticed that certain conditions cause it but it is incredibly loud when it does happen. I guess I am inclined to believe it is the fan but I'm not sure.