Knocking and buzzing noise under shifter (2001 TJ, 123k miles, 32RH)

Gibsonfirebird12

Gibsonfirebird12

TJ Enthusiast
Supporting Member
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May 26, 2020
Messages
124
Location
New Hampshire
Hello all,

Have an '01 TJ, 32 RH 3 speed auto with 123k on the clock. Just yesterday I started hearing the noise in the below video. It occurs when I am at a very slow speed or totally stopped in drive. I do not hear it at all in neutral or park. Also, if I change from drive to neutral and back it usually goes away until the next stop. It sounds like it's coming from under the shifter more towards the passenger side.

It's hard to hear under the jeep, but the noise appears to come from the area right behind the oil pan. I thought it might be the heat shield that sits right next to the shifter area on passenger side but I lightly whacked that with a hammer and it seems solid.



IMG_3440

I checked the transmission fluid quality and quantity and they both appear to be good.

Any thoughts on what it might be? I've had it about a year and a half and haven't heard this noise before.

BTW
- jeep drives fine besides the noise. shifting is smooth.
- have a fairly new 4x4 cable shifter, fairly new trans mount (mopar), and brand new mini cats.
 
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Is the middle body mount on the passenger side rusty, getting rusty, solid, or gone? Mine was rusty. Couple months back, it started making noise, but it was more of a knock or creak, than a buzz. It went away, as I think the rust opened up a bit, LOL.

I would block the wheels, set the park brake, have someone step on the brake in drive while you listen to try and pinpoint the noise. Those things drive me nuts.
 
GEEP4ME said:
Is the middle body mount on the passenger side rusty, getting rusty, solid, or gone? Mine was rusty. Couple months back, it started making noise, but it was more of a knock or creak, than a buzz. It went away, as I think the rust opened up a bit, LOL.

I would block the wheels, set the park brake, have someone step on the brake in drive while you listen to try and pinpoint the noise. Those things drive me nuts.
Click to expand...

I will do that. In the meantime, if anyone has any other potential ideas, I am all ears.

Def not the body mount, all of mine are solid. A few months ago I had a loose one and while I was at it, checked all of them.
 
Look at the exhaust bracket located above the trans mount. there is a rubber isolation bushing inside the bracket. They wear over
time and will cause a rattling /buzzing noise.

If you find this to be the issue. You can order a replacement bushing.

https://www.quadratec.com/products/57605_0016.htm
I know it says 2012-2018, but it fits from 1997 thru current models.


s-l640.jpg
 
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TJ Jim said:
Heat shield above the tranny
Click to expand...
I don't think it is this, but can't say 100% for sure. The heatshield seems pretty intact.
williambmac said:
Look at the exhaust bracket located above the trans mount. there is a rubber isolation bushing inside the bracket. They wear over
time and will cause a rattling /buzzing noise.

If you find this to be the issue. You can order a replacement bushing.

https://www.quadratec.com/products/57605_0016.htm
I know it says 2012-2018, but it fits from 1997 thru current models.


View attachment 281493
Click to expand...
I checked this out (see attached photos). Bushing looks to be intact, though covered in dry mud. I gave the exhaust a light whack with a rubber mallet and didn't notice any rattling/movement.

I also brought the TJ to my local shop for them to look at, they claim it is a lifter. It doesn't at all sound like a lifter to me. Why would a lifter only make noise in drive and reverse?

I took another video more pronounced, https://streamable.com/c8jfhk . If anyone who has had lifter problems can comment if this at all sounds like a lifter problem I would appreciate it.

IMG_3451.jpg


IMG_3452.jpg
 
Gibsonfirebird12 said:
I don't think it is this, but can't say 100% for sure. The heatshield seems pretty intact.

I checked this out (see attached photos). Bushing looks to be intact, though covered in dry mud. I gave the exhaust a light whack with a rubber mallet and didn't notice any rattling/movement.

I also brought the TJ to my local shop for them to look at, they claim it is a lifter. It doesn't at all sound like a lifter to me. Why would a lifter only make noise in drive and reverse?

I took another video more pronounced, https://streamable.com/c8jfhk . If anyone who has had lifter problems can comment if this at all sounds like a lifter problem I would appreciate it.

View attachment 281877

View attachment 281878
Click to expand...
That is not a lifter.Any technician trying to pedal that off as a lifter noise…… has no right being in the business.
 
That noise sounds like something grounding out against the body or frame while loaded (reverse/drive).
I would check and make sure nothing in the glove box is rattling. I have had this happen numerous times with customer vehicle.

Get someone you trust to assist you. Have them apply the park brake, start the jeep, apply the brakes and drop it in drive.
Crawl underneath and start feeling around to see if you can isolate the noise.
Possibly a heat shield, rear cat converter desinegrated, 4wd shift linkage.
 
williambmac said:
That noise sounds like something grounding out against the body or frame while loaded (reverse/drive).
I would check and make sure nothing in the glove box is rattling. I have had this happen numerous times with customer vehicle.

Get someone you trust to assist you. Have them apply the park brake, start the jeep, apply the brakes and drop it in drive.
Crawl underneath and start feeling around to see if you can isolate the noise.
Possibly a heat shield, rear cat converter desinegrated, 4wd shift linkage.
Click to expand...

I agree with you on your theory that it sounds like something grinding against the frame or body under load. That's exactly what it sounds like to me as well... I've gone under a few times with my SO in the Jeep (surprised she didn't run me over...LOL), and it sounds like it's coming from the area right behind the oil pan but it's very hard to tell under the Jeep with it on so I can't say for certain.

I just installed a brand new cable shifter so I am thinking it is not that. I did have a rattling under there before from the old linkage, this is a much louder/more pronounced sound. My rear cat (which I believe is original) does sounds a little hollow but it doesn't make any rattling noises. My minicat downpipes do not seem to be touching anything either, and those are new.

I think heat shield is the most likely culprit. I'm not seeing any signs of it being an issue, but it's really the only thing left besides the tranny itself. I think at this point, I'll be bringing it to another shop for another opinion, because I'm driving myself nuts and spending way too much time trying to figure it out...will update when I have more.
 
New plot twist.

Today I went back in and under the Jeep to do more diagnosis. I had my SO come out again with me and switch between R and D. It was still making the noise, and while I was under the Jeep she got hot so she put the AC on. The noise got much louder with the AC/blower on, however it is still present when it is off. does this provide any more clues?

Still can't pinpoint the noise when under the jeep, too many other noises happening. From inside the jeep, it still sounds like it's under the shifter on the passenger side, or maybe on the bottom of the dash.
 
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I'm so confused, brought the Jeep in to another shop, one kind of far away from me but that I trust to give me good answers on things. They told me that it is a rocker or rocker arm, though they did not take the valve cover off to actually look. Though they're a very capable shop, they are not well versed on the 4.0L and recommended I take it to a guy who knows jeeps really well near them. I really did not think this was engine related but now I've had two shops say it is (one said it sounded like a lifter, the other said it sounded like a rocker arm), but this is definitely over my head at this point. I likely won't be able to bring it in to the other shop for another few weeks, so I will update if and when I have more info. Sounds more involved than I expected.
 
I have brought the Jeep now to two more shops and got two totally different answers.
After bringing it to the "Jeep expert", he told me it's piston slap and not to be concerned with it unless it starts getting worse.
I had another shop look at it, and they said it is nothing power train related, and almost certainly something in or on my dash making the noise.
No idea what to think anymore. At this point I'm just waiting for something to break to really know, but that's not how I like to play these types of situations.

Here's a better video:

https://streamable.com/c8jfhk
 
Exhaust is rubbing on something. Start at the manifold and follow all the way back to the tip and look for poor clearance.
 
TJ Jim said:
Exhaust is rubbing on something. Start at the manifold and follow all the way back to the tip and look for poor clearance.
Click to expand...
Interesting theory. I got new mini cats right before the noise started (not directly, but maybe a few weeks or so).

I went under the Jeep and here are the two areas with the least amount of clearance. One is the area where the mini cat pipe wraps around the oil pan, it doesn't seem too bad, it's about an inch of clearance - and the other is the mini cat pipes themselves, very close together. They're practically touching. Is this normal? Is there a safe way to determine if this is the area causing the issue? (maybe something I could put in there to dampen the sound that won't melt?)

IMG_4172.jpg


IMG_4174.jpg
 
If those pipes have clearance to each other with it not running, they aren't going to flex enough to touch each other. Keep following the exhaust back by the transmission. The noise definitely sounds like exhaust rubbing something.

Did you also have the third cat replaced or just the two mini cats? If not, and you can't find any place outside the exhaust that it's touching something else, might pull the third cat out and see if it's broken up inside and rattling

The exhaust should have some movement in it by design, give it a push or pull in a few different spots and see if you can hear it hitting something
 
If it were the exhaust, I'd think it'd make that sound regardless of whether it's in gear or not. It sounds to me like a vibration that is induced when the transmission is engaged. I think you were on the right track with getting underneath while someone is moving through the gears like you're doing. good luck
 
Trevlaw said:
If those pipes have clearance to each other with it not running, they aren't going to flex enough to touch each other. Keep following the exhaust back by the transmission. The noise definitely sounds like exhaust rubbing something.

Did you also have the third cat replaced or just the two mini cats? If not, and you can't find any place outside the exhaust that it's touching something else, might pull the third cat out and see if it's broken up inside and rattling

The exhaust should have some movement in it by design, give it a push or pull in a few different spots and see if you can hear it hitting something
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they have clearance, but VERY little. We're talking on the order of a millimeter or less.

Following the exhaust back further, there are no other areas that seem to have clearance issues. There's an area around the oil pan with about an inch, attached, but it doesn't seem like enough to me.

I pushed up on it like you suggested, and the only noise I am hearing is a slight creak in the area where the pipes are close (the above picture). I tested the exhaust all of the way back to the end, and I'm not seeing anything remotely concerning from a clearance perspective, other than what I highlighted above.

IMG_4172.jpg
 
JC123 said:
If it were the exhaust, I'd think it'd make that sound regardless of whether it's in gear or not. It sounds to me like a vibration that is induced when the transmission is engaged. I think you were on the right track with getting underneath while someone is moving through the gears like you're doing. good luck
Click to expand...

Right. I haven't spent too much time troubleshooting the exhaust for that reason. I am no expert, but wouldn't it be areas that receive torque by being in gear? besides the transmission and motor, what would those be? (not ruling out the transmission or motor, just wondering what else I can look at?)

I would also think the fact that it only happens in gear would also indicate it not to be a lifter tick, or a piston slap, as both those would be occurring in park. would you agree with that?
 
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