Scraping metal sound

TJK said:
Does it make a difference if the sound remains even when not moving?
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Absolutely. If the vehicle isn’t moving then the driveshafts aren’t spinning, I don’t think anything would be moving in the transmission. If the noise gets faster as rpm’s increase and the Jeep is stationary I would have to think it’s engine or belt driven accessory/pulley.
 
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jwilkinson01 said:
Absolutely. If the car isn’t moving then the driveshafts aren’t spinning, I don’t think anything would be moving in the transmission. If the noise gets faster as rpm’s increase and the Jeep is stationary I would have to think it’s engine or belt driven accessory.
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hmmm well that may be good news then. The sound definitely remains when stationary.
 
TJK said:
hmmm well that may be good news then. The sound definitely remains when stationary.
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Possibly good possibly not.

Don’t get too caught up on “where” the sound is. It’s part of it, but crazy enough sounds can seem one place and caused from another.

The earlier answer is correct, if you are in N, and rev the engine, and the sound increases and it speeds up, then it’s (most likely) somewhere engine related or parts bolted on the engine.

I would open the hood with it running and have someone Rev it, see if there is a culprit. I trend to go easy checks first.

1. Make sure you have enough oil, ha.

2. Pulleys, metal grinding do any of the pulleys touching the serpentine belt throw obvious sound.

I’ve chased a squeak in the belt, a mechanics stethoscope can help, it a long screw driver touching components and next to your ear is old school.

The pulleys are usually fairly easy to change.
 
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With engine off (I know... DUH, right?) look around the bits that normally move and see if there are any witness marks of anything touching something else. Look inside areas that something moves inside of, like the fan shroud making sure the fan isn't touching, etc. Use your phone camera to help see into areas that your eyes cannot...
 
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mjbcomp said:
Could it be a backed out bolt on the torque converter hitting the flex plate?
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The torque converter is bolted to the flex plate, so if anything it would be a TC bolt hitting the inspection plate, although that sounds horrible when it happens.

TJK said:
Does it make a difference if the sound remains even when not moving?
Click to expand...

Torque converter is spinning even when the jeep isn't moving. I don't know what a cracked flex plate sounds like but its another thing that moves even when the jeep isn't.

I had a bad bushing on a distributor that made enough racket I could hear it from inside the jeep. And it also spins regardless of vehicle speed. Just tossing out ideas.
 
jwilkinson01 said:
If the vehicle isn’t moving then the driveshafts aren’t spinning, I don’t think anything would be moving in the transmission.
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We talking about an automatic? In neutral during idle the input section will rotate. In gear, it's held stationary and the TC just spins. In all cases the transmission pump is doing it's thing, and is tied to engine RPM.
 
hear said:
We talking about an automatic? In neutral during idle the input section will rotate. In gear, it's held stationary and the TC just spins. In all cases the transmission pump is doing it's thing, and is tied to engine RPM.
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I have zero experience with autos, that's why my statement was non-committal.

Edit: I am not even 100% sure on manuals.
 
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TJK said:
hmmm well that may be good news then. The sound definitely remains when stationary.
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That is almost exactly how my alternator sounded before the pulley sheared off alternator shaft. Check for loose pulleys.

Water pump, tensioner, idler, PS, all that stuff
 
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jwilkinson01 said:
I have zero experience with autos, that's why my statement was non-committal.

Edit: I am not even 100% sure on manuals.
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I didn’t know jack about them until I started opening them up, and I still have more questions than answers, despite having rebuilt several.

But as far as what moves and what doesn’t, I have that much under control. Barely.
 
UPDATE

So I brought to mechanic yesterday. He said driveshaft/u-joints/cv joints are fine. He couldn't actually hear the sound when inspecting. I picked up today and while the sound was gone upon start up, it returned again after a few kilometres. I parked and kept the engine running and opened the hood. no odd sounds from the engine bay. I crawled underneath and sure enough could hear the squeak from underneath the transmission skid plate. I turned off the engine and inspected further. I found the squeak again when putting pressure on the heat shield. Looks like it might just be a squeaky bushing on the heat shield. I bent the heat shield slightly and the sound disappeared. I'll go under again tomorrow in the light and see if I can tighten things up. I feel dumb for not figuring this out sooner.
 
TJK said:
UPDATE

So I brought to mechanic yesterday. He said driveshaft/u-joints/cv joints are fine. He couldn't actually hear the sound when inspecting. I picked up today and while the sound was gone upon start up, it returned again after a few kilometres. I parked and kept the engine running and opened the hood. no odd sounds from the engine bay. I crawled underneath and sure enough could hear the squeak from underneath the transmission skid plate. I turned off the engine and inspected further. I found the squeak again when putting pressure on the heat shield. Looks like it might just be a squeaky bushing on the heat shield. I bent the heat shield slightly and the sound disappeared. I'll go under again tomorrow in the light and see if I can tighten things up. I feel dumb for not figuring this out sooner.
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Do NOT feel dumb for that, ha!

Squeaks and sounds are a PITA, and make use all chase crazy, ha.

I get it done it, but always stop and say “whew, could have been a way worse like a transmission wasted , who knows what, ha”
 
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