Knocking sound from clutch?

[Johnep93]

I have a 04 with the 4.0 and 5 speed. Last couple times I've driven it more than a couple of miles, I've noticed when it warms up, it makes a very distinct knocking sound, but when I push the clutch pedal to the floor it goes quiet. Even on initial start up, when the clutch is out of makes this growling sound. Any suggestions before I dive into a clutch job, or is it something else?

 

[skrelnik]

That sounds like more of a transmission issue than clutch issue. When the clutch is depressed the transmission is disconnected from the engine and is therefor not turning. When the transmission is in gear and the clutch engaged, the TOB generally will not make any noise due to the torque applied to the main shaft.

So it could be the input shaft bearing, I hope, and nothing major.

I would also recommend doing a tranny fluid change to RedLine MTL

https://www.amazon.com/dp/B000CPCBEG/?tag=wranglerorg-20

 

[Johnep93]

That sounds like more of a transmission issue than clutch issue. When the clutch is depressed the transmission is disconnected from the engine and is therefor not turning. When the transmission is in gear and the clutch engaged, the TOB generally will not make any noise due to the torque applied to the main shaft.

So it could be the input shaft bearing, I hope, and nothing major.

I would also recommend doing a tranny fluid change to RedLine MTL

https://www.amazon.com/dp/B000CPCBEG/?tag=wranglerorg-20

It's in neutral at a stop when I hear it. Clutch out. Push the clutch in and the knocking stops.

 

[bromel]

It's normal. It's the input shaft spinning the bearings in the transmission. When you push in the clutch, the engine disconnects and the bearings stop spinning. The NV3550 is a naturally loud transmission, and there is no soundproofing between it and the floorboards. You'll see a million threads about the topic on the forums; trust me, it's normal.

 

[Chris]

It's normal. It's the input shaft spinning the bearings in the transmission. When you push in the clutch, the engine disconnects and the bearings stop spinning. The NV3550 is a naturally loud transmission, and there is no soundproofing between it and the floorboards. You'll see a million threads about the topic on the forums; trust me, it's normal.

X2. Based off everything I've heard and read about this transmission, I'd have to agree.

 

[MaloStapalo]

I have a 04 with the 4.0 and 5 speed. Last couple times I've driven it more than a couple of miles, I've noticed when it warms up, it makes a very distinct knocking sound, but when I push the clutch pedal to the floor it goes quiet. Even on initial start up, when the clutch is out of makes this growling sound. Any suggestions before I dive into a clutch job, or is it something else?

Does the growling sound come from right where the transmission mounts to the back of the engine? When clutch out and in neutral I hear a mechanical sounding "whirring", is that what you're hearing? I'm told it's normal. I also have the nv3550

 

[ac_]

It's in neutral at a stop when I hear it. Clutch out. Push the clutch in and the knocking stops.

I tend to agree with the others that it is normal. These are noisy transmissions. Usually though it is noise more than knocking, so if it is truly knocking that might be something to be concerned about, but to add to what everybody else is saying.

When you are in Neutral with the clutch out the transmission is moving but with no torque to your rear driveline, but when you put your clutch in it completely disconnects the transmission from the engine and it stops moving altogether.

So from what you are saying it is definitely coming from your transmission rather than your clutch, but the debate will be if it is normal or not.

Having one of these transmissions once, I tend to agree what you are talking about is normal, but not being able to hear it clearly, I hate to stake my life on it.

Do you know anybody with the same setup you can compare noises with?

 

[bromel]

I have the same transmission and the only noise I can compare it to is to imagine a big jar of marbles spinning around. It's indistinct when cold, but when hot it's quite loud. If that's the noise you're referring to, it's normal. When I first got my TJ, I thought I had a busted transmission

I noticed the noise became slightly quieter by switching from the Mopar gear oil to Redline MTL.

 

[TJDon]

Mine makes all kinds of noise also. I have 190k and thought it could have been a TOB also and wanted to replace the clutch anyways. Put it all back together and still just as loud as it was. Normal trans noise
I do want to change out the trans fluid. I’ll do the redline fluid to ty and tame down the clatter


Sent from my iPhone using Tapatalk

 

[Johnep93]

I tend to agree with the others that it is normal. These are noisy transmissions. Usually though it is noise more than knocking, so if it is truly knocking that might be something to be concerned about, but to add to what everybody else is saying.

When you are in Neutral with the clutch out the transmission is moving but with no torque to your rear driveline, but when you put your clutch in it completely disconnects the transmission from the engine and it stops moving altogether.

So from what you are saying it is definitely coming from your transmission rather than your clutch, but the debate will be if it is normal or not.

Having one of these transmissions once, I tend to agree what you are talking about is normal, but not being able to hear it clearly, I hate to stake my life on it.

Do you know anybody with the same setup you can compare noises with?

I'll accept the growling sound as normal. But that knocking just started a couple weeks ago, and I've driven it twice since then. That knocking is NOT normal for my jeep. The growl has been there from jump street. This knock is new, and I don't hear it while driving, just sitting still in neutral and after driving it for a bit. I commute 60 miles round trip and driven the jeep to work many times never heard that knocking sound. Gonna throw this out cause what the heck, the jeep is throwing code P0161.

 

[ac_]

So it looks like that code is a bank two heater circuit 02 sensor code. I doubt that has anything to do with your transmission now, but in case you don't know when you start your car up cold, the 02 heater circuit cheats your PCM into thinking your exhaust is hotter than it is. It is only used at start up, so you should only get that code during cold starts. Meaning if you clear the code you should get it almost right away not during driving conditions.

I had the same code on mine when I first bought my jeep. and it ended up being a broken ground wire on my O2 harness side of the pigtail. I just repaird it, and it has been fine ever since, like 2 years now.

I am not sure how much of an electrician you are, but it isn't that difficult to trace a heater circuit for 02 sensor. There is only two wires per sensor, IIRC, and one goes to the PCM and the other goes to ground. So you can trace the ground wires to ground and you can trace the PCM wires to the PCM and make sure there are no breaks or corrosion.

As far as your transmission. I believe you. Unfortunately, you live on the other side of the world from me. It is possible that the front bearing lost a ball, or you have a broken tooth in your transmission, but if you put your clutch in and the noise goes away, then nothing in your transmission is moving, so it is pretty easy to say it is something in there.

It might be possible that it is in your transfer case also. You might be able to eliminate it by putting the transfer case in neutral. and the transmission in neutral, and pushing your clutch in and out and seeing if the noise is still there. Because putting your transfer case in neutral and your transmission in neutral should eliminate the transmission from moving and then letting the clutch out will make the transmission move even in neutral, but no torque through the back of the transmission. Any torque still going through the transfer case should be lost at the planetary gears, so nothing else in the transfer case should move or not enough to make any audible noise. It isn't exact but could be a deciding factor.

Thinking about it putting your transfer case in neutral really isn't going to help because even with your transmission moving in neutral, it isn't enough to move your transfer case anymore whether it was in neutral or in gear. in either case you are losing the torque in the planetaries. So don't listen to that garbage about the transfer case. All of the other stuff is true though.

 

[Johnep93]

So it looks like that code is a bank two heater circuit 02 sensor code. I doubt that has anything to do with your transmission now, but in case you don't know when you start your car up cold, the 02 heater circuit cheats your PCM into thinking your exhaust is hotter than it is. It is only used at start up, so you should only get that code during cold starts. Meaning if you clear the code you should get it almost right away not during driving conditions.

I had the same code on mine when I first bought my jeep. and it ended up being a broken ground wire on my O2 harness side of the pigtail. I just repaird it, and it has been fine ever since, like 2 years now.

I am not sure how much of an electrician you are, but it isn't that difficult to trace a heater circuit for 02 sensor. There is only two wires per sensor, IIRC, and one goes to the PCM and the other goes to ground. So you can trace the ground wires to ground and you can trace the PCM wires to the PCM and make sure there are no breaks or corrosion.

As far as your transmission. I believe you. Unfortunately, you live on the other side of the world from me. It is possible that the front bearing lost a ball, or you have a broken tooth in your transmission, but if you put your clutch in and the noise goes away, then nothing in your transmission is moving, so it is pretty easy to say it is something in there.

It might be possible that it is in your transfer case also. You might be able to eliminate it by putting the transfer case in neutral. and the transmission in neutral, and pushing your clutch in and out and seeing if the noise is still there. Because putting your transfer case in neutral and your transmission in neutral should eliminate the transmission from moving and then letting the clutch out will make the transmission move even in neutral, but no torque through the back of the transmission. Any torque still going through the transfer case should be lost at the planetary gears, so nothing else in the transfer case should move or not enough to make any audible noise. It isn't exact but could be a deciding factor.

Thinking about it putting your transfer case in neutral really isn't going to help because even with your transmission moving in neutral, it isn't enough to move your transfer case anymore whether it was in neutral or in gear. in either case you are losing the torque in the planetaries. So don't listen to that garbage about the transfer case. All of the other stuff is true though.

I know a guy that had a dodge cummins that made a knocking sound when its TOB went out, so I'm hoping that's what it is. I'll try poking the bear Sunday to see if I can get it to reproduce and get it on video. I'll also try your trick with the Tcase, just to see. I'm better at just straight wrenching than diagnostics. Given how much a clutch assembly costs I may just get one, and if its fine I'll find a trans shop and just tote it there on my own and save some labor. How would you inspect a TOB to see if it was bad, or is it something you would just know immediately? I appreciate the help.

 

[ac_]

Just something to think about. If you your foot is not on the clutch pedal, your t/o bearing is doing nothing, but sitting there on the input shaft. It is not touching anything, so therefore cannot make any noise. It will only make noise if you push your clutch in. That is when your to bearing engages the clutch cover and spins.

 

[PeterNC]

I know a guy that had a dodge cummins that made a knocking sound when its TOB went out, so I'm hoping that's what it is. I'll try poking the bear Sunday to see if I can get it to reproduce and get it on video. I'll also try your trick with the Tcase, just to see. I'm better at just straight wrenching than diagnostics. Given how much a clutch assembly costs I may just get one, and if its fine I'll find a trans shop and just tote it there on my own and save some labor. How would you inspect a TOB to see if it was bad, or is it something you would just know immediately? I appreciate the help.

Sorry to bring old post back but what was you solution. I am hearing the same clanking sound form the bellhousing area on my 5 speed. Not the normal marbles in a jar sound...Mechanical clank in time with the engine RPM at idle with the clutch out.