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2002 Jeep Grand Cherokee Laredo 4X4
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Discussion Starter #1
I have a 2002 WJ with a 42RE and NP242. I've looked everywhere and cannot find anyone talking about this specific issue, but I did find a video of it.


I have the same identical symptoms displayed in the video. In reverse, I get movement (and can back the vehicle), but I get the ratcheting/knocking noise. In a forward gear, I don't. I recently replaced the transmission fluid and filter (and switched to a drain plug pan because the old one was a little dented and had been overtorqued). I've put about 6 quarts of fluid (estimating, since I had to add some from changing out the neutral safety switch that started leaking after I'd done the change), and the level looks good. I used the proper ATF+4, and used a Mopar gasket. The old fluid looked pretty clean but not brand new, and there weren't any funny shifts or anything; it was really just to deal with the pan and gasket since it had a little drip from that overtorqued pan.

It didn't have this issue beforehand, so I'm wondering if there was something in the transmission pan area that could've been knocked loose (pressure solenoid or something?) that could cause this. It didn't gradually start, either. I changed the fluid, had done some other work on it over a few weekends, and this was the first drive out of the garage just backing it out since the change.

Any ideas? I feel like the easiest thing is the just pull the pan again, and check that there's nothing loose or disconnected. I feel like that's a long shot, though.
 

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2002 Jeep Grand Cherokee Laredo 4X4
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Discussion Starter #4
It's not my video, but I have the same exact symptoms. According to the description, the vehicle is on jackstands.
 

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2002 Jeep Grand Cherokee Laredo 4X4
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Discussion Starter #5 (Edited)
Finally got a chance to spend some real time troubleshooting this. I'm 99% sure it's the flex plate bolts hitting the spacer plate between the transmission and engine. The inspection plate was already gone (not the first thing like that I've found missing on this heap). The two bolts in view look like they've just started contacting; a little rubbing, but not very beat up. It's only been run a max of 5 minutes total, maybe about 30 seconds of that in gear.

I was reading some posts elsewhere (not even Jeep related) trying to find anything on the issue, and found one where this issue started on a ZJ immediately after lifting it. I did just do the Rough Country lift, but also did the transfer case drop, so I didn't think that would be an issue, but it prompted me to test it out.

I pushed it out of the garage, started it up, and ran it through the gears a few times (except R) with no noise, then back to R, the noise started again, so I shifted it to D and pulled it back in. The a-ha moment came when I went over the bumper in front of our garage door in D...right then it made the noise and immediately stopped when the drivetrain settled.

The transmission mount is dead as well, so I've already got that on order to replace. The one thing I'm not sure of is how to straighten out that plate; it does look a little warped. This is the plate I'm referring to: J3237847 - Genuine Mopar SHIM-CLUTCH HOUSING

After some more thinking, I wonder it I should do away with the transfer case drop (1") since I have a brand new IRO double cardon sitting on the shelf waiting to get installed. It seems to put the engine/trans at a pretty back-leaning angle..
 

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2014 Summit 5.7 4wd 20" tires swapped to 18", added all skid plates
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Finally got a chance to spend some real time troubleshooting this. I'm 99% sure it's the flex plate bolts hitting the spacer plate between the transmission and engine. The inspection plate was already gone (not the first thing like that I've found missing on this heap). The two bolts in view look like they've just started contacting; a little rubbing, but not very beat up. It's only been run a max of 5 minutes total, maybe about 30 seconds of that in gear.

I was reading some posts elsewhere (not even Jeep related) trying to find anything on the issue, and found one where this issue started on a ZJ immediately after lifting it. I did just do the Rough Country lift, but also did the transfer case drop, so I didn't think that would be an issue, but it prompted me to test it out.

I pushed it out of the garage, started it up, and ran it through the gears a few times (except R) with no noise, then back to R, the noise started again, so I shifted it to D and pulled it back in. The a-ha moment came when I went over the bumper in front of our garage door in D...right then it made the noise and immediately stopped when the drivetrain settled.

The transmission mount is dead as well, so I've already got that on order to replace. The one thing I'm not sure of is how to straighten out that plate; it does look a little warped. This is the plate I'm referring to: J3237847 - Genuine Mopar SHIM-CLUTCH HOUSING

After some more thinking, I wonder it I should do away with the transfer case drop (1") since I have a brand new IRO double cardon sitting on the shelf waiting to get installed. It seems to put the engine/trans at a pretty back-leaning angle..
Some of the youtube videos of these kinds of noises said they traced it to the U-joints, that their lift had over extended the joint and caused problems. I don't see why it would be related to the flex plate, it turns in the same direction whether you are in D or R and I can't think of any reason one would push it in or out opposite to the other.
 

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2002 Jeep Grand Cherokee Laredo 4X4
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Discussion Starter #7
Some of the youtube videos of these kinds of noises said they traced it to the U-joints, that their lift had over extended the joint and caused problems.
It does it while stopped with the brake on, not just while moving, so u-joints wouldn't be contributing here (but they're probably trashed anyhow and are getting changed soon).

I spent some more time this afternoon/evening working on it. It's absolutely the dust cover that sits between the engine and transmission getting hit with flex plate bolts. I had my wife turn the crank with a breaker bar and could feel it contacting it just near the starter. The dust cover is bent in that area, like maybe a bolt was hitting it before and they pried it away from the bolt heads in that area.

I pulled the starter (which I needed to do anyhow to fix a makeshift kill switch the PO put in), and wedged the cover away enough that I could get my inspection camera in there. Sure enough, there's a giant scar where the bolts are hitting there. When they bent out the lip on it, it bent in that area.

I went ahead and replaced the transmission mount as it was completely gone, and the parts store had one in stock. That helped a little bit, but just also revealed that the motor mounts desperately need to be changed as well. I don't think that'll affect the dust shield issue, though. I'm tempted just to cut that section away for now with a cutting wheel so I can drive it. I don't see any why to bend it back without potentially making it worse in another area that might not be reachable.
 

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2014 Summit 5.7 4wd 20" tires swapped to 18", added all skid plates
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It does it while stopped with the brake on, not just while moving, so u-joints wouldn't be contributing here (but they're probably trashed anyhow and are getting changed soon).

I spent some more time this afternoon/evening working on it. It's absolutely the dust cover that sits between the engine and transmission getting hit with flex plate bolts. I had my wife turn the crank with a breaker bar and could feel it contacting it just near the starter. The dust cover is bent in that area, like maybe a bolt was hitting it before and they pried it away from the bolt heads in that area.

I pulled the starter (which I needed to do anyhow to fix a makeshift kill switch the PO put in), and wedged the cover away enough that I could get my inspection camera in there. Sure enough, there's a giant scar where the bolts are hitting there. When they bent out the lip on it, it bent in that area.

I went ahead and replaced the transmission mount as it was completely gone, and the parts store had one in stock. That helped a little bit, but just also revealed that the motor mounts desperately need to be changed as well. I don't think that'll affect the dust shield issue, though. I'm tempted just to cut that section away for now with a cutting wheel so I can drive it. I don't see any why to bend it back without potentially making it worse in another area that might not be reachable.
Sounds like good news overall, at least you know the cause. Is it possible to drill a hole thru the dust cover and use one of those slide hammer dent pullers to pull it out 1/8"?
 

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2002 Jeep Grand Cherokee Laredo 4X4
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Discussion Starter #9
That's a good idea. I just bought a slide hammer a few weeks ago, so I might try that if I have the room under there.
 

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That's a good idea. I just bought a slide hammer a few weeks ago, so I might try that if I have the room under there.
My 69 Firebird 400 had three bolts holding the torque converter to the flex plate. One of them fell out and got trapped in the bell housing. Intermittently made a hell of a racket when it got caught. Sounded a little like yours.
 
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