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Discussion Starter #1
A few seconds after I start my truck I hear a growling noise. It is not extremely loud and it only lasts a second or two. Startup is the only time I hear this noise. I've had it to the Dealer a few times and they claim they don't hear it. Anyone else hearing this?
 

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I think I hear the same noise you are refering to. As far as I can tell it is the vacuum motors in the HVAC system putting the routing flaps into the position dictated by the control settings. I say this because I only hear it when I start the truck with the system active.
 

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I've had a short growling or woofing noise a few times, shortly after startup, within a few seconds of firing up. I haven't been able to detect a pattern because it happens so rarely. I figure it must be something "cycling", like maybe the turbo vanes or the EGR valve, or??? Sounds like it could be something opening and shutting?
 

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i have my truck straight piped and i have that loud growling noise when i start up my truck.. and after a few seconds, when the oil pressure builds, it goes away and i get the whistle from the turbo.. next time you start up your truck when its cold, watch the oil pressure gauge.. and when that come up.. the rumble will go away.. just my .02
 

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I recently started having the same thing on my 06.
About two seconds after you start it (cold start), something growls from under the hood. Sounds like something is going horribly wrong under there (not engine, maybe turbo?). Then about 1 second after it starts, it ceases.

I have no clue.

I'll try starting without the AUTO AC on and see if maybe it's belt slip or the AC compressor clutch.
 

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Discussion Starter #7
Lotsa good ideas. I also believe it is something re-positioning but have no idea what it could be. I don't think it has anything to do with the AC as it is around freezing in my part of the country and I don't have he AC on. But like everyone else, i hear it a second or two after starting and it goes aways in about 2 seconds. I'll keep my eye on the oil pressure next time I start it.
 

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[ QUOTE ]
Lotsa good ideas. I also believe it is something re-positioning but have no idea what it could be. I don't think it has anything to do with the AC as it is around freezing in my part of the country and I don't have he AC on. But like everyone else, i hear it a second or two after starting and it goes aways in about 2 seconds. I'll keep my eye on the oil pressure next time I start it.

[/ QUOTE ]I didn't specify that it was the AC, I merely said it was part of the HVAC system, which is heating, ventilation & air conditioning. Like I said, since the noise only occurs in mine when I have my HVAC set to anything but off, I believe the noise is related to the vacuum motors pulling the air direction flaps into what ever position the system is telling them to be in (the vacuum bleeds down over night and the flappers relax to their static position until vacuum is reapplied upon startup). Try makeing sure the system is off (to include vent) when you shut down for the night and see if you have the noise the next moring.
 

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V.A.C.U.U.M. P.U.M.P.

We have an electronic vacuum pump that runs our HVAC and SOTF 4WD hubs. That noise is the vacuum pump charging the system. If you don't start the motor, it will make the noise anyway.
 

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[ QUOTE ]
i have my truck straight piped and i have that loud growling noise when i start up my truck.. and after a few seconds, when the oil pressure builds, it goes away and i get the whistle from the turbo.. next time you start up your truck when its cold, watch the oil pressure gauge.. and when that come up.. the rumble will go away.. just my .02

[/ QUOTE ]

That's your turbo vanes closing after startup.
 

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same/similar problem here. I came here looking for answers to this issue. Upon cold start only, loud noise from under hood, then okay in a few secs. Turned motor off and it did not happen again.

Yesterday was the first time this happened to me though.

05 f250 diesel 6.0 Weather has dropped to around 15 degress overnight this week.
 

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MY 03 7.3 USE TO GROWL AND WHINE ON START UP WHEN IT WAS COLS, i ALWAYS FIGURED IT WAS THE HPOP AND THICK OIL. MY 06 WILL GIVE A SHORT GROWL ON COLD START UP. WE HAVE SEEN TEMPS DOWN TO 0 ALREADY THOUGH.
 

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Okay, it is the HVAC system as was reported eariler in this thread. This morning, I turned off my HVAC before starting. No noise.

I then turned the air on and it happened.

So, now the question is, why is this happening now, and it never did before. Is it the cold weather??

Oh, and thanks so muh to the members of this forum, I was going to cancel an upcoming trip this weekend because of this noise (until I could get it looked at). Now I'm not worried.

Thanks!! /ubbthreads/images/graemlins/biggrin.gif
 

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Discussion Starter #14
My bad; i related HVAC to AC which is incorrect.

i'll try turning off the HVAC later when i go out. thanks for all the replies.
 

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Did any solution ever come of this? We've all had trucks with HVAC before and never had this sound. What is odd for me is that it just started. Durring the summer I started my truck plenty of times with the A/C (HVAC) on and never heard this before.
 

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If you Cycle your heater controls a few times (with the engine off, key on), you will hear the noise again. Both my '02 and '06 have always made this noise.
 

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I'm pretty sure I have the same noise.

It's not the vacuum pump, I am aware of that noise. It's not the HVAC system, as a few of you mentioned that when I previously created a thread about this. I've let the vacuum pump shut off, cycled all of the HVAC dampers, etc. then started the truck...I still get the noise.

One thing I did noticed though. Every time the noise occurs, it happens right when the oil pressure gauge is sweeping from 0 to normal.

Someone mentioned turbo vanes, that was my initial thought as well. that they were repositioning as oil pressure built in the system.
 

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I'll often get a growling noise on startup that comes from the A/C compressor. If I've left it on when I shut down the engine before or if I turn it on right away after startup. Sounds awful! Goes away quickly and doesn't come back until I do the startup again.
 

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I just found this thread on search. I've had this noise since I got it back from headgaskets, oil and EGR coolers. Didn't notice it before. It's been cold and it seems that it's worse on cold startup.

I'll try shutting the HVAC off before shutting down overnight and I'll see if the 'growl' is present or not upon cold startup in the A.M.

Take care
 
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