Hey guys. I was wondering whats up with my engine. It sounds 3 different ways when it runs.
Sometimes when i first start it it has a really loud "whoosh" air noise when i accelerate(not the jet engine whistle). This usually stops after a minute.

Then it sounds one of two ways.

The good way, it sounds like a jet engine about to take off. When i stomp it the turbo whistles loudly and the motor itself is relatively quiet.

The bad way. The turbo whistle is very small, and all you hear is the motor noise loudly.

Is there a reason this would randomly do this?

Maybe a bad sensor that is not having the veins move right?

Its a new turbo installed by the dealer.

I want to give them an idea of whats wrong before i take it back.

BTW it did this before the new turbo too

mine starts, idles fine then bogs and then starts hissing at me. the whole thing last maybe 15 seconds then its fine. is this what yours does?

No, i think the its just the wastegate holding open until the motor warms up, im not a diesel mechanic though so i dont really know

o neither am i. i dont think our turbos are waste gated though. they are the variable vane turbo so that may have something to do with it.?

Your turbo is functioning correctly bud. The sound you are hearing are the vanes opening and closing around the outgoing flow of exhaust from the turbine wheel. Before the engine warms up, the vanes will cycle closed providing the most resistance against the flow of exhaust, therefore allowing the heat to build up before it is vented to the atmosphere. This is simply an efficient means of utilizing the variable characteristics of the turbo. If you tap on the accelerator as this is occuring (only 5-15% of throttle position), you can almost control the vanes as they cycle open and closed when this cycle is occuring.;)

so is mine messed up? mine only does it for 15 sec tops then just goes back to a regular idle.

so is mine messed up? mine only does it for 15 sec tops then just goes back to a regular idle.
No sir, they cycle on and off repititiously. It only stays closed for a few seconds/minute or so I guess depending on atmospheric conditions and ambient temps as input by baro sensor and intake temp sensors (LBZ/LMM has 2). So long as your vanes are cycling open/closed, the turbo should be functioning just fine (assuming the shaft is spinning and it has oil pressure of course;)). If there were a position fault, the vane position sensor should provide the feedback for such issues.

Hey guys. I was wondering whats up with my engine. It sounds 3 different ways when it runs.
Sometimes when i first start it it has a really loud "whoosh" air noise when i accelerate(not the jet engine whistle). This usually stops after a minute.

...

The first description sounds like the fan clutch is engaged...sometimes the viscous fluid pools and takes a minute, or so, for the clutch to disengage when you first start out. Mine does that from time to time as the mornings get cooler.

Fan engagement at startup, known as "morning sickness," is often reported. Many posts on this condition, such as

http://www.dieselplace.com/forum/showthread.php?t=391629&highlight=morning+sickness

Quit roddin' on your cold motor!

The first description sounds like the fan clutch is engaged...sometimes the viscous fluid pools and takes a minute, or so, for the clutch to disengage when you first start out. Mine does that from time to time as the mornings get cooler.


Kinda what I was thinking too.

Anyone know if the fan clutch would be covered under the 5/100K factory engine warranty?

If not, how much would I be looking at to have a new fan clutch installed?

Mine seems to have this "morning sickness" on rare occasion- is it really something to worry about, or just leave it be for a while?

Just get used to it. There is nothing ab normal about it. The owners manual says your engine may even be louder in cooler weather.

if i recall correctly, i read somewhere that the fan clutch engages when the motor is cold to provide resistance and warm the motor up sooner. i don't know. sounds odd. run the fan to warm up? maybe

i would say it is definitely not a warranty issue and i would not replace the fan clutch. every chevy truck i have owned did this when it got cold outside. it goes away after a mile or two. just drive it easy till it warms up

if i recall correctly, i read somewhere that the fan clutch engages when the motor is cold to provide resistance and warm the motor up sooner. i don't know. sounds odd. run the fan to warm up? maybe

i would say it is definitely not a warranty issue and i would not replace the fan clutch. every chevy truck i have owned did this when it got cold outside. it goes away after a mile or two. just drive it easy till it warms up
I tried to find that thread, it had to do something with having the fan run when the truck was cold or something similar to this topic now? I had some input in that also but I couldnt find the thread. Basically, IIRC someone had mentioned they thought the fan was cooling the engine before it reached operating temperature. Therefore, lengthening the time for the engine to reach operating temp. I responded by stating it cant cool the coolant before the thermostats any further if the thermostats hadnt yet opened. Regardless of the little amount of coolant that makes it past the bypass route into the tank/radiator. Theoretically, if the fan is running, it will induce a load on the engine, creating a higher energy draw and therefore more btu (heat). The energy required to run the fan, far exceedes the small amount of air passing over the slightly exposed metal surfaces of the engine, which might if any all, result in energy loss by convection.

mine would do the same all last winter, but this year even when it was 90 degree's and leaving work at 3:00 pm my fan would would come on at start up and run for the first mile , even when i sat there for a minute or two before taking off , just like when it was cold out. still never overheated. asked dealer about it and they told me that it was normal. everything is normal at a dealership .

There is still the second noise issue. Sometimes, i will drive 40 miles to work, and it will sound fine. Quiet motor, mildly loud jet engine whistle turbo noise. Good.

Sometimes, i will drive 40 miles to work, and it will sound not so fine. The motor is loud, and you can barely here the turbo whistle.

Sometimes, it will start out bad and then all the sudden just sound good.

Wierd.......

There is still the second noise issue. Sometimes, i will drive 40 miles to work, and it will sound fine. Quiet motor, mildly loud jet engine whistle turbo noise. Good.

Sometimes, i will drive 40 miles to work, and it will sound not so fine. The motor is loud, and you can barely here the turbo whistle.

Sometimes, it will start out bad and then all the sudden just sound good.

Wierd.......
Do you get this noise w/o the use of the Bully Dog tuner? If you run on performance the timing is going to be very advanced, the inj psi will be very high and the injectors will be extremely loud if you get into it a little more than simply light driving. Some of the more aggressive tuners will exhibit such conditions due to the programming. This is not a condition you want to continue engaging in if this is whats happening. I have had customers running certain similar (very similar) tunes on Cummins trucks and have cracked nozzles! Haven't had a Dmax do this yet though. If you add a lift pump or performance cp3 kit or several other type of fueling upgrades to aggressive "race" type tunes, injector damage can result.

Very advanced timing and cold engines with hard throttle kills head gaskets and lots of known parts. Warm that thing up before you go out and jump on the go stick. Diesels need extra care and that warm up and cool down care, most know it but new guys need to get the habit to help the truck last. Hard lessons happen after warranty and cost alot. Take the time to take care of that Duramax or any engine it's the same deal. It's not discussed enough with winter coming it is most important. That truck will go 300k miles with care. Lots don't care because they trade in a few yrs. so be it. That's the used market with unknowns anyway. We need a thread on Winter Starts and Care going now to help guys who are new. Reminders are just good anyway really.

Mine does the whooshing when it's cool out...like below 60* usually. Generally it goes away after a minute or two. I just assumed it was normal....

Your turbo is functioning correctly bud. The sound you are hearing are the vanes opening and closing around the outgoing flow of exhaust from the turbine wheel. Before the engine warms up, the vanes will cycle closed providing the most resistance against the flow of exhaust, therefore allowing the heat to build up before it is vented to the atmosphere. This is simply an efficient means of utilizing the variable characteristics of the turbo. If you tap on the accelerator as this is occuring (only 5-15% of throttle position), you can almost control the vanes as they cycle open and closed when this cycle is occuring.;)

X2 that is correct. I love that sound. it is extreamly noticable too, guy who lives across the street from me can hear the idle change inside his house and mines just a 4" straight pipe.

No, it has no connection with the tuner. I hardly ever romp on the pedal anyways, i like my good mileage. I never hit it when its cold.

your idlers are all good?