Is the T in TJ for Trivia? Let's start with noise...

ARae4TJ

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Joined
Sep 12, 2017
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27
Location
Denver, CO, United States
Hi ya'll, I just bought a 97, great condition, runs great, just needed reg maint, shocks, and front sway bar links. So I lifted the front end (jacked up by the bumper) put shocks and sway bar links in, simple right! Set her down for a test drive and BAM! WTHeck some howling whistling metal to metal noise came from under the dash which started at 20 mph and increases with speed, lift her off the ground entirely and run her through all gears-NO NOISE! While I was under her I did notice the manifold was cracked in half! Replaced that after the fact. Anyway all this logically suggests a weight bearing issue, replaced wheel hub assy's even though I had no wobble or issue (she really runs good but the noise is relentless). U-joints are strong and steady although I tend to do these tedious things regardless and have them ready to put on. Noise doesn't come from turns is same no matter what - acceleration into the wind. The T-Case was replaced in 2012, fluid good, I flushed the differential fluids, no metalic parts, color good, etc. I have ruled out drive train, off the ground I have to rule out transmission. I do my own work, typically, but after the eyes of a 5th mechanic which is baffled too I now pose to you the trivia of the day. Any ideas? Could this simply be an HVAC fan bearing issue as the sound comes from under the dash or could I have bent the frame? Bring it!
 
Have you checked all the vacuum lines? Mine wistles but only when I let off the gas. By metal to metal do you mean a grinding noise? I can't imagine a metal to metal whistling noise from under the dash. I am not an expert. And welcome to the forum!
 
Have you checked all the vacuum lines? Mine wistles but only when I let off the gas. By metal to metal do you mean a grinding noise? I can't imagine a metal to metal whistling noise from under the dash. I am not an expert. And welcome to the forum!
Thanks for the welcome! It is a very light weight metal buzzing, like air blowing between two thin metal pieces making a bzzzz which screams and howls the faster you go. Mu noise goes up with speed and down with deceleration, also, a semi passed me the other day and that made it worse for a second. Wind has got to have something to do with this. I did used carb/throttle cleaner and sprayed around most areas to check for a vacuum leak. Nothing.
 
Hmmm, this is an odd one. I'm trying to figure out if it's truly a drivetrain issue (metal on metal), or if it just sounds like one and it's coming from under the dash.

First thing I would do is check under the vehicle and look for any signs of metal rubbing on metal (i.e. wear points on the driveshafts, etc.). If you don't find anything, then it's got to be something inside the cabin.

Does it happen all the time, or only when the blower fan is on, the radio is on, or some other condition?
 
Hmmm, this is an odd one. I'm trying to figure out if it's truly a drivetrain issue (metal on metal), or if it just sounds like one and it's coming from under the dash.

First thing I would do is check under the vehicle and look for any signs of metal rubbing on metal (i.e. wear points on the driveshafts, etc.). If you don't find anything, then it's got to be something inside the cabin.

Does it happen all the time, or only when the blower fan is on, the radio is on, or some other condition?

I don't use A/C so I haven't had to use the blower. It only happens when there is forward movement suggesting a weight bearing issue or a wind issue. It makes no sound off all 4 wheels all the way through 5th gear. Starts as speed picks up, if a semi passes by it flares up then resumes its "normal noise" after the gush of wind has passed. I went as far as stripping my jeep of the hood mounted jack, and bumper to diagnose this. Since I have replaced the wheel hub assy's, exhaust manifold (I found it was cracked when doing the shocks), etc. 5 mechanics verified it is not drive train. I changed my differential fluids the other day too as front smelled but was clean and had no grit. The T-case was overhauled a few years ago, the only thing I don't agree with is they used 5W30. So I will be flushing that. She runs great, smooth, strong and steady, no symptoms but the noise. It is in the shop right now, and I never go to the shop, that mechanic is baffled too and being determined to diagnose this he is going to send it to a specialist he knows.
 
Could it potentially be a small piece flapping in the wind? that could potentially make that noise. I only think this because when you put in new shocks in I would assume you got a little taller off the ground with the potential to let more wind through the underparts of the jeep. I cant think of anything off hand that would make that noise but mabye check heat shields in the area if there are any. Could be vibrating like a kazoo? Idk its a long shot but sounds like a wind thing. Dont worry if i sound crazy thats ok.
 
Could it potentially be a small piece flapping in the wind? that could potentially make that noise. I only think this because when you put in new shocks in I would assume you got a little taller off the ground with the potential to let more wind through the underparts of the jeep. I cant think of anything off hand that would make that noise but mabye check heat shields in the area if there are any. Could be vibrating like a kazoo? Idk its a long shot but sounds like a wind thing. Dont worry if i sound crazy thats ok.

Ya know that is a new one, not sure I have heat shields though, I am new to Jeep, but sure does seems to be a wind thing to me too. Thx for the input, VallenMaes!
 
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Sounds like a doppler effect. That would be wind related.
 
Going out on a limb here- friend of mine had a LED bar that made a howl of noise the faster he drove. Any accessories of the type on your TJ?


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I would suggest checking your top and see if it is off ever so slightly. If it is only while moving, any where wind can get in the jeep can make the most horrific noise.
 
Unlikely, but Any chance there is crap in the cowl? I've heard of strange sounds from under dash due to whatever being trapped in the cowl. Heard one guy had some rebar or something in there.

Did you get this issue resolved? If so what was it?
 
Ya know that was actually the problem, the dang light-bar!

Hey, worked out and good to read that it was something as simple as that! But you probably drove yourself crazy, as did my buddy. Light-bar is definitely not on my wants list!


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