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Horrible Grinding Sound
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Posted by: bl3wbyu

HELP! I don't know what this sound is, but it sounds horrible!

Friend said it sounded like the bottom end of the engine, but it seems to have something to do with the drivetrain.

With it in gear, foot on the brake, giving it some gas to build up against the brake, it'll start grinding. Put it in neutral and give it gas, and it'll grind for a second, then stop grinding until you put it in gear again. So, it seems to only do it (at least pronouncedly) when under load.

I ran out and took a video of it a little while ago. In a lot of places you can't hear it because of wind noise, but I'd GREATLY appreciate it if you'd watch the whole thing and listen, because you can hear it quite well at a few places.

Any input would be greatly appreciated!!!

Posted by: Mugen_K20A

That video was awful. But I could hear the noise you were talking about when you stopped and stuck the camera out the door. Is this the Cherokee in the picture? If so, is it four wheel drive? Because it doesn't necessarily change with engine RPM so I don't think it's the engine. If it is a 4x4, it might be the transfer case. I can see its an automatic though. It might be your front pump or the torque converter might be bad. Its not easy to tell from your video. It might just be pinging from bad gas too.

Posted by: John

I dunno, it's hard to tell. This Mugen dude (dudette?) might be right. I don't think it sound like an engine knock for the reasons he already mentioned. It might be something stupid like a heat shield rattling or something too.

Are you sure it's coming from the front end and not like the back? A bad pinion bearing could make similar noises.

Posted by: rodslinger

I know exactly what that is as I've seen it a bunch of times. It's real simple......

.....something is broke.

Posted by: An11SecRanger

I can't tell by that video.
It could be a cracked flex-plate.

Posted by: bl3wbyu

Thanks for all the advice, folks; really appreciate it.

Posted the vid up on some Jeep forums, and a problem with the flex-plate or a loose torque converter seem to be a popular idea. Either way, Dad's got me going to a transmission shop for them to look at it tomorrow.

Hopefully I'll have some kind of a concrete idea of what's going on soon.

Thanks again!

Posted by: bl3wbyu

Just as an update...

Took it to a transmission shop, hoping it was the flexplate or torque converter, realizing it could be the engine or transfer case or something else. They listened to it, put it on a lift, used a stethoscope, and proclaimed it has a knocking connecting rod.

Ok, that's bad news. It's knocking pretty loud...means that crank's gotta be chewed up a bit. But, HOPEfully not TOO bad and I can just replace the bearings for that connecting rod and get some more mileage out of it.

Met Dad for lunch, he rode around in it, just couldn't convince himself that it was coming from the engine from the way it sounded, so we took it to a Jeep specific shop. They finished lunch real quick, brought it in the garage, narrowed it down to the bell housing area, jacked it up, yanked off the dust cover, and viola...flexplate bolts were loose. Tightened 'em up and she's just fine!

So, I'd say that's a pretty happy ending. Oh yeah, and they didn't charge us anything!

Posted by: Grape Ape

SWEET!

So the fleplate thoughts were almost exact. I think anyone would've tought the noise was in the trans area.

Posted by: An11SecRanger

I'm glad it turned out to be something simple.
It's asTOUNding that they had it up, on a lift, using a stethoscope, and thought it was a rod knock! I couldn't tell much using the video, but it was obviously way to fast to be a rod knock.
I wonder why the bolts backed out.

Posted by: bl3wbyu

Quote:

Originally Posted by An11SecRanger


	I wonder why the bolts backed out.

I don't know, but the guys at the Jeep shop said it's a fairly common occurrence. Hopefully it'll take a while for it to happen again.

Posted by: StoneFox

nice Jesus sandals ya got there

Posted by: John

Quote:

Originally Posted by StoneFox


	nice Jesus sandals ya got there

We call 'em "Jerusalem Cruisers".

On thing I would do is check holes if you can. A wobbly flex plat can cause other bolts to get out of whack. Also, one thing, in the inspection hole, if you can see the gear ring of the flex plate, take a looong screw driver and put pressure on the ring at various spots you can get to. It shouldn't move but if it does, that's a problem. If the ring gear breaks or gets bent it's throw the balance out of whack and break your starter. Better to find a loose ring gear now and fix than get stuck somewhere.

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