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Metal on metal sound

Demonoid369

Demonoid369

NAXJA Forum User
NAXJA Member
Location
Salem, OR
220k 97' 4.0l aw4 231 xj
So I've had this metal on metal screech/squeal and I've been trying to figure out what it is.
Here's the facts. Noise comes from passenger side(gf thought of it was under the hood but the sound was coming from higher in the dash)
Happens only going from a stop and then accelerating BUT only when moving. In park or neutral it does not do it. There are no wear marks on the radiator where the mech. Fan is. The noise stops/slows down when I let go of the gas pedal.
Now my motor mounts are semi new and still in good shape, I've read a worn tranny mount can make noise and I know my tranny mount hasn't been replace but why would the worn mount make this? I know it's not a exhaust pipe vibrating on the crossmember.
My thought was the flex plate but I don't get the typical noise I've read about a crack/broken flex plate when I start my jeep.
Trying to narrow down where to look as it's hard to look under when it only happens when moving lol
 
Check to see if your fan shroud is either a.) cracked or b.) loose or if your engine moves when sitting, revving. A good way to see how much it's moving is to securely block the wheels and have someone inside (that you trust) standing on the brakes, in gear, and revving it while you keep an eye on the engine. If you have stock motor mounts and a mushy tranny mount, the engine might just move enough for the fan to hit the shroud (a pre-cursor to hitting the radiator)

My XJ had a cracked shroud and when ever I would rev it or accelerate it would suck in and contact the fan...I thought my trans was making all the noise and it was just a little plastic. A $10 fix.
 
So update: I havent gotten a chance to check the flex plate but listening to videos on YouTube makes me think it's not that. Mine is a metal something spinning and grinding on something else that's metal. I had the pleasure of being the passenger of my jeep as my gf drove around
(Scary to say the least lol) and the sound does seem to come from the engine/trans tunnel but more towards the trans tunnel. I've check the mech. Fan area and it's not that.no marks, no nothing.
It only happens when in drive and accelerating from a stop and the noise is Consistent with how much the gas pedal is pushed. Nothing happens in neutral or park. I've open the hood and pulled the throttle cable and no noise or excessive movement of the engine(motor mounts are 1 year old)
I'm very puzzled by the noise.
 
pull the rear driveshaft.
put it in 4 hi and drive it around the block.

noise on acceleration sounds like bad u joints/pinion. Sound appears to come from tunnel because that's where it gets transmitted into the body.
 
I would check the front passenger hub. Its real easy to check, jack the wheel up and with the tire one, check for excessive play 12 oclock to 6 oclock. Mine went out and would screech and grind just like you described.
 
Edit post:

Nevermind I'm a freaking idiot, little ringer thing in the side of my iPhone was on vibrate. thought the video wasn't making noise Lol
 
Last edited:
Noise comes from passenger side(gf thought of it was under the hood but the sound was coming from higher in the dash)
Happens only going from a stop and then accelerating BUT only when moving.
Click to expand...

This is a real long shot, but is there any way it could be the blower motor squirrel cage rubbing something? I listened to the video many times and it sounds much like my squirrel cage did when it started getting loose.

Maybe when you pull out, the squirrel cage is sliding back a little and making contact with something. The location of the sound as you described it would add up.
 
Bump, hoping someone know this sound and can help as I don't have a clue what it is, crack flex plate doesn't sound like the noise I posted, exhaust rubbing doesn't sound like this as I've already fixed that awhile ago lol I don't have any pinion play in my axles. Transfer case chain is only a couple years old.
 
Demonoid369 said:
It only happens when in drive and accelerating from a stop and the noise is Consistent with how much the gas pedal is pushed. Nothing happens in neutral or park.
Click to expand...

Is the noise consistent coasting in neutral versus accelerating in drive ? I would lean towards that front drive shaft. Does your year have the double cardon joint up front shaft. My 90 was bone dry and rusty when I replaced mine.

Bad tranny mounts I've had produce a thump/clunk on a hard take off.
 
Last edited:
I would get a mechanic stethoscope, their cheap. Put a long piece of hose on it. Lay the end where you think noise is, or have the misses drive while you listen. The older my hearing gets the more I use mine.

Just listened to sound bite, can you reproduce the sound by power braking instead of rolling off. I say if you can reproduce by power braking then listen closer to flex plate or tranny its self. My th350 chevy tranny cracked plates enough times I knew the sound pretty good. And it didn't take a big noticeable crack to start making noises.
 
Dragonslayer said:
Check the harmonic balancer. Look for scarring on the timing chain cover. Just a guess.
Click to expand...


Checked that, nothing. The harmonic was replaced less than a few months ago.

Bumping this again with a newer longer vid of the noise.
http://youtu.be/YRV290JSI0g

I had a idea, could this sound like a stater isn't fully retracting and is contacting the flex plate?

EHall: I've been listening to what a cracked fly wheel would sound like and everything video sounds like a rod nock. Not putting your opinion down, just trying to figure out this odd noise.
 
Really? All the noises I've heard sound like this
http://youtu.be/dhCuqgkhuxA
I don't have that at idle, my jeep is actually really silent at idle. I'll try and take a look at it, haven't had a day off in two weeks so it's been a little hard finding time lol
 
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