Whistle noise from exhaust manifold? - Defender Source
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  #1  
Old September 4th, 2005, 01:09 PM
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Mark Kurzinski
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Whistle noise from exhaust manifold?

All. I have a whistle noise coming from the exhast system somewhere under the hood. It sounds like it is coming from the drivers side possibly from the manifold area. The whistle increases in pitch as the rpm's increase (if you have ever driven next to a tractor trailer on the freeway, it sounds like the turbo booster "whistle" on a tractor trailer's diesel engine). I have read on other posts that a manifold leak sounds like a "tick", whether it comes from the manifold/head junction or the Y-pipe junction. Could this be a sign of another problem, or is the gasket on the manifold/Y-pipe leaking? Comments/suggestions greatly appreciated...
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  #2  
Old September 4th, 2005, 02:17 PM
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Could also be an intake leak, which tends to whistle a lot more often than exhaust leaks do.

-Hans
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Old November 14th, 2006, 08:45 AM
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I have noticed this on my truck occasionally? I have replaced the intake manifold gasket and was pretty methodical with tourqing etc cleaning the surfaces blah blah blah. I cant seem to tell where its coming from seems like the air intake well at least the front half of the truck. Any thoughts?
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  #4  
Old November 14th, 2006, 11:10 AM
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Robert Dassler
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Noisey alternator bearings?
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Old November 14th, 2006, 11:47 AM
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I noticed yesterday that the a/c pulley bearing whistles a little.



Neil
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  #6  
Old November 14th, 2006, 03:56 PM
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it doesnt seem bearing related, i dont really ever use the AC. I will pay more attention and report back? COuld it related to stepper motor or something in the top end of the motor? All the hoses on the air intake are tight so i am confused.
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Old September 20th, 2007, 12:55 PM
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I don't own the D90 anymore but wanted to follow up on what this turned out to be for the benefit of this forum. The "whistle" turned out to be the bearings in the alternator as Rodesiderob suggested.
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Old September 20th, 2007, 01:37 PM
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Over the past weekend, my alternator developed some really bad whining/whistling (a lot of noise) and when I popped my hood, it was throwing a lot of sparks. Needless to say I had it towed home and am about to put in a new alternator.



I have never heard of an alternator sparking. Is this common? The tach also stopped working.
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  #9  
Old September 20th, 2007, 04:20 PM
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Did you have one of these installed?
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  #10  
Old September 20th, 2007, 07:06 PM
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Sometimes (rarely) when I start the truck, I get your whistle -- and also lower rpm. I re-start, and the whistle is gone and rpms return to normal. So I'm thinking that there's some electronic actuated valve that doesn't set properly during the starting process that's allowing a small hole or air leak into the intake system. Weird. If it was happening all the time, I'd have to sort it out....
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  #11  
Old November 25th, 2007, 07:40 PM
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Revisting the whistle thread. I have begun to notice this again. It is most noticable at 2000-2300 rpms, but while the engine isnt under much "load". It has been intermitent for sometime, based on the last post over a year. It sounds exactly like the turbo charger when tractor trailer is passing by. If I am maintaining speed it will appear but if I mash the gas it goes away imediately. I am not convinced it could be my alternator. Any other thoughts? Has anyone had a similar noise?
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  #12  
Old November 27th, 2007, 08:39 PM
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Rover4x4:

One diagnostic would be to drive the truck without the trumpet on the air filter housing. If the whistle is coming from the throttle butterfly or stepper motor, the noise will be louder without the trumpet. I get the whistle sometimes when Lord Lucas aligns all the cosmic tumblers; pretty often actually. I've convinced myself it is the sound of engine sucking the air; rushing past the the nearly closed throttle butterfly at part throttle. i believe this because, just like you said, the noise ceases as soon as you press on the gas and the throttle butterfly opens.

DKJ
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