High pitched sound under load
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High pitched sound under load
OK. I've looked everywhere and found a couple of threads that I thought were similar but turned out not to be.
So here goes. I'm pulling a 12,500 pound trailer. We're going up a 4 to 6% grade. I'm in OD. The truck goes out of OD and I hear this high pitched sound. It almost sounds like an electronic warning device. I let off the accelerator just a little and the sound immediately goes away. It does not sound like a belt slipping. It is only under these conditions that this happens. By the way there is no loss of power and no other symptoms.
Anyone got any ideas?
The truck is a 2002 7.3 PSD. It is a 450 model.
Thanks,
HamRad
So here goes. I'm pulling a 12,500 pound trailer. We're going up a 4 to 6% grade. I'm in OD. The truck goes out of OD and I hear this high pitched sound. It almost sounds like an electronic warning device. I let off the accelerator just a little and the sound immediately goes away. It does not sound like a belt slipping. It is only under these conditions that this happens. By the way there is no loss of power and no other symptoms.
Anyone got any ideas?
The truck is a 2002 7.3 PSD. It is a 450 model.
Thanks,
HamRad
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Joined: Jun 2007
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From: Hampton, Maryland.
Could it be that your fan clutch engaged the fan and because of this extra load, the belt did indeed start slipping and causing your high pitched sound? I know you said it doesn't sound like a belt slip, but I know of no high pitched warning indicator in the cab or otherwise that would come in to play.
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I suppose it could be the fan but it doesn't sound like what I'm used to hearing for a slipping fan.
The sound has a muffled sound to it. Don't know if that makes sense or not. It is actually somewhat difficult to hear but it definitely is there. For awhile I though I was just imaging things. Now I listen specifically for the sound any time I get in the proper conditions.
It does not seem to be effecting performance in any way.
Thanks for response. Thought I'd post to see if anyone else has ever experienced the same thing.
Later,
HamRad
The sound has a muffled sound to it. Don't know if that makes sense or not. It is actually somewhat difficult to hear but it definitely is there. For awhile I though I was just imaging things. Now I listen specifically for the sound any time I get in the proper conditions.
It does not seem to be effecting performance in any way.
Thanks for response. Thought I'd post to see if anyone else has ever experienced the same thing.
Later,
HamRad
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Joined: Nov 2007
Posts: 9,549
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From: Payson, AZ
I suppose it could be the fan but it doesn't sound like what I'm used to hearing for a slipping fan.
The sound has a muffled sound to it. Don't know if that makes sense or not. It is actually somewhat difficult to hear but it definitely is there. For awhile I though I was just imaging things. Now I listen specifically for the sound any time I get in the proper conditions.
It does not seem to be effecting performance in any way.
Thanks for response. Thought I'd post to see if anyone else has ever experienced the same thing.
Later,
HamRad
The sound has a muffled sound to it. Don't know if that makes sense or not. It is actually somewhat difficult to hear but it definitely is there. For awhile I though I was just imaging things. Now I listen specifically for the sound any time I get in the proper conditions.
It does not seem to be effecting performance in any way.
Thanks for response. Thought I'd post to see if anyone else has ever experienced the same thing.
Later,
HamRad
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The boost is going into an area I'm not familiar with because I've never had the problem. I'm only guessing belt because the fan clutch may be putting enough load on the belt to cause one that is going south already to start complaining. This is something I've experienced.
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From: White Mnt's,New Hampshire
not saying its not a belt..just posable it could be a boot,,they will have a high pitch sound under higher boost## kind of like letting a air out of a baloon by pinching the end of it..
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From: Hampton, Maryland.
That sounds like a good possibilty Ron. Good call. If it's not a belt/fan issue, I bet it's a boost leak.
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From: Buckingham, IA
Ditto on what Ron said. When you put greater pressure into the system with higher boost #'s things can start to loosen up and leak. I would check all the clamps between the turbo and the heads. We made a plug to put into the boot after the turbo to pressurize the system in the shop. Used the pressure regulator on the line to control the pressure so as not to blow anything. Kind of tricky to be sure that air doesn't leak out through the valves though. We did determine what the problem was not.
For what it's worth, we also had a problem with the exhaust turbine causing a similar noise. Found out that it had touched the housing and bent and broke some of the fins and would make a noise under load only. A new turbo later the noise was gone.
For what it's worth, we also had a problem with the exhaust turbine causing a similar noise. Found out that it had touched the housing and bent and broke some of the fins and would make a noise under load only. A new turbo later the noise was gone.
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From: Blairsville,Ga
mine didn't hurt anything but sure worried me some on the 750 mile drive home
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From: 21791
To the original poster- do you know what normal turbo operating sounds are? It should produce a high pitched whistle noise when under a heavy load. As long as the "siren" whistle is constant and goes away when you let off of the pedal, thats normal. Sorry to be so elementary about it, but some people do not know what a normal sound is. On the other hand, if you get a pulsating "chuff chuff chuff" sound intermittantly during a heav loaded condition, it could be compressor surge.