First Duramax, I've had it since last December, 2500 4x4 CC LB 06 LLY and I love it. I upgraded from an 04 Dodge Cummins. The Dodge was pretty quiet, Chevy is silent in comparison. However, what I have noticed is when towing or not, most times when I roll on the throttle (I'm not a lead foot at all) it almost seems the engine is kind of hissing, it's a strange sounding engine, not like its working at all. Maybe hissing isn't the right description, more like a hissing/soft scraping/nothing terrible but it is nothing like the grunt the Cummins made when pulling stuff around, sounded like a truck. I don't have complaints about power or MPG, both are excellent. Pulls my 14K toyhauler up 6% grades 55-60 and would go faster if I wanted to, round trips with that weight are 10 MPG, empty I get 20 at 65 MPH and average about 17 mixed. I'm just curious if I have some sort of intake leak or something or maybe just because the thing is so damn quiet that is its normal sound.

Thanks,
Bill.

I notice a slight hissing when under a load. Mine sounds like it's coming from the engine compartment, drivers side close to where I sit. How 'bout yours?

Ed

Sweet sound of a turbo??? Kinda sounds like it might be..

yeah, I would blame that sound on a properly functioning turbo.

It is not the turbo if it is the same that I have. I do agree, it is hard to describe but mine sounds like a gasket leaking. It is not a continuous sound and it is not on a set beat. It is only under acceleration and when the radio is turned down when I can hear it. If I am driving across a bridge or with some sort of a wall on the drivers side and with my windows down I hear it even better. I think the only thing that would decribe the sound is a pressure cooker. When the water is boiling with the weight on the vent, as the weight is dancing the psss psss psss sounds it makes is very close. I have been wanting to bring the truck in to have it checked but I haven't had the time and I can't think of how to describe it to them so they don't look at me as if I am crazy. I am curious if that has anything to do with the lack of power I have on my truck. Anyone else out there that is hearing this sound having any differences in power since it was new?
Bill, does this sound like yours?

Jeff

It is not the turbo if it is the same that I have. I do agree, it is hard to describe but mine sounds like a gasket leaking. It is not a continuous sound and it is not on a set beat. It is only under acceleration and when the radio is turned down when I can hear it. If I am driving across a bridge or with some sort of a wall on the drivers side and with my windows down I hear it even better. I think the only thing that would decribe the sound is a pressure cooker. When the water is boiling with the weight on the vent, as the weight is dancing the psss psss psss sounds it makes is very close. I have been wanting to bring the truck in to have it checked but I haven't had the time and I can't think of how to describe it to them so they don't look at me as if I am crazy. I am curious if that has anything to do with the lack of power I have on my truck. Anyone else out there that is hearing this sound having any differences in power since it was new?

Ditto, but no power loss.

maybe the oil pump?

My favourite noise "TURBOSPOOLIN"

Is is a waste gate open and closing rapidly under a load? maybe

I don't think it is a waste gate. This is under very low pressure/load. I can drive my truck empty and like my grandpa (with a very soft foot) and I can hear it when leaving a red light. It does get louder under more acceleration. I have tried it with the tranny in Neutral and I don't hear it then. I have been trying different things to narrow it down but no luck yet.

Jeff

No wastegate on LLy and LBZ

i agree with Duromax04. No wategate on the variable vane turbos.

where is your air ride compressor located?

Sorry about that, went on vacation for a couple weeks.
Eddysel and Acehi: Noise is on drivers side for sure, near the windshield. I have not driven any other 06 LLYs so maybe it is normal. It does come and go so maybe turbo spooling is what I hear. No complaints about power but I've got no references for it either, pulls my 14K lb. trailer fine. I'll just let 'er run, I was just curious if others had found it strange.
Bill.

My air ride compressor is in the engine compartment on the drivers side mounted under the support bar, next to the firewall, and to the right of the brake master cylinder. But I really doubt the noise would be that. It is motor related. As far as I know, it could be the fuel injectors making the noise, but it is something I have never heard on my 01 LB7. It is a faint noise but noticable when the music is low or off and when driving across a bridge with solid walls or when there is a barrior wall on the drivers side.

Jeff

do you have simulators on your wheels?

i am hearing the same thing in my truck as well...

Simulators? Whats that?

I have the same noise,I am wondering if this is related to a air deflector behind the fan forcing air in all directions under the hood with new exit points that were their in the past but the old under hood air exit points were on the right side due to the fan design. The noise seems to disappear with more road speed and engine speed masking the noise? just a thought !

With so many people with the same noise i wouldn't be worried about it. Its probably normal.

Good point, Riccas. Love the avatar, by the way. :D

I'm wondering if there isn't a firewall grommet that has an opening in it, letting wind whistle through now and then.

I don't have the sound but guess I'm gonna be listening for it now. :lol:

I have it too....................but I never noticed it until after the blocker plate/stick install. I checked all the plumbing on the turbo/ intercooler and the plate for leaks and found nothing.

Ever occur to anyone i just might be the sound of it sucking air? More throttle= more air flow. Go to the tractor pulls sometime and listen when they are going down the track. Just my 2 cents worth.

I have a sound like that , from the same location and apparently the same volume.
But mine is a stuttering sound, especially over rough road , it sounds like the turbo is cutting in and out or that there is a vaccum leak.
Does anyone have a sound that does that? I don't recall the sound being there when the truck was new and it's enough for me to take it in to get looked at.

It is most likely the turbo spinning up, as another enthusiast stated previously. Even the smallest incline will put a load on your rig, thus the demand for boost from the turbo, once you are up to speed, backing off the throttle, or starting down any grade the demand will decrease and the sound will fade.

It is always good to remember that when you are working that turbo it is getting hot, under most driving I would say it is about 350`to 650` (though I can't be exactly sure how hot) under a heavy load\pull it will get even hotter. So just remember, when your pullin hard be kind to your D-max and let her idle for a minute to cool that turbo down and let it spin down before you shut it off.

I can hear the turbo whine seperately , it is a smooth and consistant whine.:ro)

This other sound I hear resembles the whine of a turbo but can be described better as a stuttering , choppy, hissing sound that is present even not when towing.

I said it sounded like the turbo is cutting in and out because if you can imagine hearing the smooth whine of the turbo and then imagine a wire on the turbo being loose that is vibrating and grounding the turbo out at a fast sporatic rate , thats what it sounds like.
Just wondering if the other people here that have the hissing have the same sound.:confused:

I think all we're hearing is air being sucked into the engine. If you pull the intake tube off you'll hear it MUCH louder. :) I don't suggest driving around with your intake disconnected, but if you want to confirm that the hissing is air being sucked into the engine, that's one way you could do it.