Engine noise when letting off throttle
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Senior User
Joined: Oct 2003
Posts: 124
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From: SoCal
Engine noise when letting off throttle
Last weekend we went to Oceano dunes and saw a LOT of Superduty 7.3 and 6.0 diesels. I noticed a common noise though when we would all help out a stuck rig. When in 4 hi or 4 low, you get on the throttle and get going, but as soon as you let off the throttle, it sounds as if the cooling fan kind of scrubs against something. Thats just what it sounds like though. I cant imagine the turbo making any sort of noise. Does any body know if the transfer case or anything else could cause this noise??
Post Fiend
Joined: Oct 2002
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You're probably hearing the turbo blow back.... since the 6.0 has no wastegate to purge off excess (or bult up and unused) boost...
ANYTIME I am building boost and chop the throttle I hear the "huffing" of the pressurised air "backing up" the intake since the normal path into the intke is now blocked and it has nowhere to go.... so it goes to the path of least resistance - back out the intake...
ANYTIME I am building boost and chop the throttle I hear the "huffing" of the pressurised air "backing up" the intake since the normal path into the intke is now blocked and it has nowhere to go.... so it goes to the path of least resistance - back out the intake...
New User
Joined: Jul 2003
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I agree with jdadamsjr. His description of your problem is normal. Mine does it as well. When you stab the gas and back uot quickley you get a pop..pop..pop.. from the turbo. In knuckle drager circles we call it a turbo fart...
Cargo Master
Joined: Jun 2003
Posts: 2,203
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From: Carlsbad, California
Same occurs with mine, mostly when towing with a heavy load. When I snap off the throttle quickly - like when some idiot pulls out in front of me - I hear the venting noise.
Don't usually hear it otherwise, but then my hearing isn't that great these days.
Don't usually hear it otherwise, but then my hearing isn't that great these days.
Freshman User
Joined: Jul 2004
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It sounds like what I called a puff back in an earlier thread. Basically its boost with no place to go. I have been told that this is very hard on the turbo so I try to adjust my driving habits to eliminate this
Post Fiend
Joined: Oct 2002
Posts: 11,314
Likes: 4
Hmmm...
hard on the turbo ?
I'd have to see some idea of how that was determined .....
maybe reverse flow... but it would be miniscule...
hard on the turbo ?
I'd have to see some idea of how that was determined .....
maybe reverse flow... but it would be miniscule...
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6th Gear
Joined: Sep 2004
Posts: 6
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I have 2004 ford with the same noise. three dealers later and two front hubs they told me the sound is normal. It seems to get louder as it gets older. 38,000 lariat. It's sad ford would make a truck that sounds like it need hubs and sell it for 38,000. If people knew this before buying they might think twice.
Post Fiend
Joined: Oct 2002
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WHOA Awesone tool (and I won't be verifying THAT username 
)
we are talking about the turbo blowback here....
not sure what you're talking about, but we have a lot of enthusiast on this site that will try to help if you want to give us a little insight to your tirade
)we are talking about the turbo blowback here....
not sure what you're talking about, but we have a lot of enthusiast on this site that will try to help if you want to give us a little insight to your tirade
6th Gear
Joined: Sep 2004
Posts: 6
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thank for reply. I went to dealer and drove two new 2004 6.0 deisel truck today and they make the same noise. The main differance is my truck noise from fuel injection intake has increase at least fifty percent in the ten month and 12,000 miles it currenty has. I own five ford trucks all deisel my 2002 deisel 550 has no intake noise at all. Does any one know how loud it will be at with 20,000 . I dont want to get pulled over for noise pollution ha ha.
Postmaster
Joined: Aug 2003
Posts: 4,483
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From: Central Texas
Originally Posted by awesone tool
thank for reply. I went to dealer and drove two new 2004 6.0 deisel truck today and they make the same noise. The main differance is my truck noise from fuel injection intake has increase at least fifty percent in the ten month and 12,000 miles it currenty has. I own five ford trucks all deisel my 2002 deisel 550 has no intake noise at all. Does any one know how loud it will be at with 20,000 . I dont want to get pulled over for noise pollution ha ha.
FTE Leadership Emeritus
Joined: Jan 2003
Posts: 161,999
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From: 3rd Rock
Originally Posted by awesone tool
I have 2004 ford with the same noise. three dealers later and two front hubs they told me the sound is normal. It seems to get louder as it gets older. 38,000 lariat. It's sad ford would make a truck that sounds like it need hubs and sell it for 38,000. If people knew this before buying they might think twice.
6th Gear
Joined: Sep 2004
Posts: 6
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My problem is with the blow back on my 6.0 deisel fuel injection. No one else has posted anything on if noise has become louder in their engines over time. Is this normal to keep increasing? I had to step on gas hard before to make this noise but nowing it happens all the time under regular driving conditions.