Weird humming noise...

pookie · **Joined:** Wed Feb 07, 2007 10:06 am **Posts:** 48

After wheeling 2 weekends ago and after a long road trip this weekend I noticed the KJ making a weird humming noise. I'm going to describe it the best I can. It sounds like it is coming from the rear under the passenger seats. It increases and gets louder the faster you drive. And it only happens when you step on the gas. When you step on the gas it makes noise, if you are just coasting no noise. It doesn't sound like a bad wheel bearing and it is coming more from the middle of the Jeep.

I have gear oil as I was thinking of changing my diff fluid anyways when all this started.

Any thoughts?

tjkj2002 · **Posted:** Tue Aug 28, 2007 1:45 pm

pookie wrote:

After wheeling 2 weekends ago and after a long road trip this weekend I noticed the KJ making a weird humming noise. I'm going to describe it the best I can. It sounds like it is coming from the rear under the passenger seats. It increases and gets louder the faster you drive. And it only happens when you step on the gas. When you step on the gas it makes noise, if you are just coasting no noise. It doesn't sound like a bad wheel bearing and it is coming more from the middle of the Jeep.

I have gear oil as I was thinking of changing my diff fluid anyways when all this started.

Any thoughts?

Check your muffler,it may have been pushed up some and hitting the heatshield causing the noise.If it was the rear end it would be making the noise all the time,might want to check the t-case fluild level though.

BeepBeepJeepJeep · **Posted:** Tue Aug 28, 2007 1:46 pm

I hate to say it but it sounds like exactly what happened to me. If I were a betting man i'd say you got water in your rear dif and your gears are cut up.

tjkj2002 wrote:

pookie wrote:

After wheeling 2 weekends ago and after a long road trip this weekend I noticed the KJ making a weird humming noise. I'm going to describe it the best I can. It sounds like it is coming from the rear under the passenger seats. It increases and gets louder the faster you drive. And it only happens when you step on the gas. When you step on the gas it makes noise, if you are just coasting no noise. It doesn't sound like a bad wheel bearing and it is coming more from the middle of the Jeep.

I have gear oil as I was thinking of changing my diff fluid anyways when all this started.

Any thoughts?

Check your muffler,it may have been pushed up some and hitting the heatshield causing the noise.If it was the rear end it would be making the noise all the time,might want to check the t-case fluild level though.

Partially true. The noise is barely audible when your foot is off the gas. When your foot is on the gas it reverberates throughout the cabin at certain speeds with the windows up (for me it's 40-50mph when it's most noticible)

callaway · **Posted:** Tue Aug 28, 2007 1:46 pm

do you have skids? did your tranny skid get pushed into your exhaust?

pookie · **Joined:** Wed Feb 07, 2007 10:06 am **Posts:** 48

No skids.

Didn't go through any real deep water, mostly just making splashes, in other words real light wheeling, just kind of got it dirty.

Muffler seemed to move a little bit last night. I just kind of crawled under to see if there was anything stuck or leaking any fluids.

I changed the t-case fluid about 2 maybe 3 weeks ago. That's why I have the gear oil I was going to change that too and never got around to it.

I'm not driving it and my other buddy is coming over tomorrow anyway to help me wire up my CB so we are going to check it out. Does the rear diff have a gasket or is it similar to the auto tranny where you make your own gasket using the gasketmaker stuff? I am going to go ahead and pop the cover and change the fluid either way.

Also you can hear it going forwards only, you can't hear it in reverse. And like I said only when on the gas. At 30-45 it is the loudest. At 50-60 it is there but not as loud. At 65-75 it is there but faint. At 75+ you don't hear it at all.

There is also a hose on top of the rear axle on the driver side that is broken off. I didn't trace where the hose is coming from or goes, I just notice it looks like it comes from the back bumper into a T on the driver side and then branches off. The T is upside down on the top of the axle and the broken part of the hose is the long end going into the T. Sorry that is not a great description but I just remembered seeing that and all my manuals are at the house. I should be able to get a pic later tonight. I hope. I won't be home til after dark though.

pookie · **Joined:** Wed Feb 07, 2007 10:06 am **Posts:** 48

Quote:

I hate to say it but it sounds like exactly what happened to me. If I were a betting man i'd say you got water in your rear dif and your gears are cut up.

Man I hope that's not it. How'd you fix it? Mines an 02 with 106K and change so it is no longer under any warranty.

tjkj2002 · **Posted:** Tue Aug 28, 2007 5:04 pm

Quote:

There is also a hose on top of the rear axle on the driver side that is broken off. I didn't trace where the hose is coming from or goes, I just notice it looks like it comes from the back bumper into a T on the driver side and then branches off. The T is upside down on the top of the axle and the broken part of the hose is the long end going into the T. Sorry that is not a great description but I just remembered seeing that and all my manuals are at the house. I should be able to get a pic later tonight. I hope. I won't be home til after dark though.

If it is the hose labeled #1 then that is your rear axle breather,if it is #2 then that is the rear brake line.If it was the rear break line you would know it since you not have much brakes.If it is #1 then you do probally have water and dirt in the rear diff and it is toast.

BeepBeepJeepJeep · **Posted:** Wed Aug 29, 2007 7:11 am

tjkj2002 wrote:

Quote:

There is also a hose on top of the rear axle on the driver side that is broken off. I didn't trace where the hose is coming from or goes, I just notice it looks like it comes from the back bumper into a T on the driver side and then branches off. The T is upside down on the top of the axle and the broken part of the hose is the long end going into the T. Sorry that is not a great description but I just remembered seeing that and all my manuals are at the house. I should be able to get a pic later tonight. I hope. I won't be home til after dark though.

If it is the hose labeled #1 then that is your rear axle breather,if it is #2 then that is the rear brake line.If it was the rear break line you would know it since you not have much brakes.If it is #1 then you do probally have water and dirt in the rear diff and it is toast.

Yep. Just change the fluid and continue driving. It will make that noise forever

Or be prepared to spend ~$800 to get it fixed at a shop (including bearings too). I had the same problem where my rear dif breather was broken the day I bought it (used). Unfortunately I didn't notice until I got it stuck in mud/water up to the running boards, and water had a chance to drip in the rear dif for over an hour. I should have checked it as soon as I get home but I didn't think anything of it

Oh well, live and learn I suppose...

pookie · **Joined:** Wed Feb 07, 2007 10:06 am **Posts:** 48

Well hose #1 is the one that is broken. That sucks. :cry:

I haven't changed the fluid yet but it seems like I'll have to learn to drive with the stereo cranked way up loud again.

Replacement breather hose? Is there a way to keep this from happening again? Mine is broken right at the hose meets the T fitting.

Even if I have to do it tonight in the dark I plan on changing the fluid and hopefully the hose and see what happens.

pookie · **Joined:** Wed Feb 07, 2007 10:06 am **Posts:** 48

Well I answered my own questions. Yes there is a gasket for the rear diff, $4 at advance auto. And the brether hose is not listed. Jeep doesn't even have it. However, it is a 5/16 hose and any 5/16 should work.

Now my question for the gurus at Jeep is, why in the fudge would you put a cheap arse breather hose on the diff, and not make it where crap can't get in and ruin the diff. Freaking morons.

As of right now it looks like I will be changing fluid, breather hose, spark plugs, and wiring up my CB tonight.

I gotta love my wife though, she goes if you lift will it keep this from happening again? I think you need to lift it. I love her.

Thanks for the help guys

Jeepjeepster · **Posted:** Wed Aug 29, 2007 2:37 pm

The hose on my 04 seemed to be in great shape. Just check the under carriage after each offroad run to check everything. The tcase, tranny, and front diff all have those hoses so you need to check them too. The rear diff hose is kinda out in the open so mud and crap can hit it.

Go ahead and extend that breather while youre back there so it never happens again.

The breather hoses on the Liberty are higher than most cars and suvs on the road today so it has nothing to do with something that Jeep did. Any drive trail component that is sealed must have a breather since air expands when its heated and contracts when it cools.

pookie · **Joined:** Wed Feb 07, 2007 10:06 am **Posts:** 48

yeah my comment was more on why didn't they make a stronger breather. This cheap little hose broke right at the t connection. Mine is extened all the way up towards the rear bumper, where it goes after that I don't know. I guess I will find out in a few. Any idea how much hose I need to run it up higher than stock? I have to stop and get the diff gasket so I was going to get the hose too, how long a piece do I need?

bbo · **Joined:** Fri Sep 30, 2005 5:17 pm **Posts:** 382

just think how easy it will be to work under there with ~2 more inches of lift ... why if you alreayd had the lift, you probably woulda noticed that and had it fixed ... wink ... wink ....

BeepBeepJeepJeep · **Posted:** Wed Aug 29, 2007 7:02 pm

pookie wrote:

yeah my comment was more on why didn't they make a stronger breather. This cheap little hose broke right at the t connection. Mine is extened all the way up towards the rear bumper, where it goes after that I don't know. I guess I will find out in a few. Any idea how much hose I need to run it up higher than stock? I have to stop and get the diff gasket so I was going to get the hose too, how long a piece do I need?

it goes up behind the gas tank. the most common place to route it is up along the gas tank filler tube... I bought about 10 feet and I wound up using 8 or 9 feet total for all three of my breathers.

bbo wrote:

just think how easy it will be to work under there with ~2 more inches of lift ... why if you alreayd had the lift, you probably woulda noticed that
and had it fixed ... wink ... wink ....

Not necessarily true :oops:

bbo · **Joined:** Fri Sep 30, 2005 5:17 pm **Posts:** 382

BeepBeepJeepJeep wrote:

bbo wrote:

just think how easy it will be to work under there with ~2 more inches of lift ... why if you alreayd had the lift, you probably woulda noticed that
and had it fixed ... wink ... wink ....

Not necessarily true :oops:

Hence the ...wink ... wink ...

I was attempting to show a little humor and provide a plausible, if untrue reasoning for explaining the cost and work to get a lift done. Normally I just leave out the long explanation and throw a wink wink in to allow for people to reason it is somewhat a tongue in cheek reply.

feel free to take notes if it helps you to remember the wink wink explanation in any future posts I may have. I will test you on it later.

bbo · **Joined:** Fri Sep 30, 2005 5:17 pm **Posts:** 382

BeepBeepJeepJeep wrote:

pookie wrote:

yeah my comment was more on why didn't they make a stronger breather. This cheap little hose broke right at the t connection. Mine is extened all the way up towards the rear bumper, where it goes after that I don't know. I guess I will find out in a few. Any idea how much hose I need to run it up higher than stock? I have to stop and get the diff gasket so I was going to get the hose too, how long a piece do I need?

it goes up behind the gas tank. the most common place to route it is up along the gas tank filler tube... I bought about 10 feet and I wound up using 8 or 9 feet total for all three of my breathers.

back on topic .. thanks for the info ... I will need to re-do my breathers. Is there a post you used with a little how to or did you wing it?

BeepBeepJeepJeep · **Posted:** Wed Aug 29, 2007 7:45 pm

bbo wrote:

BeepBeepJeepJeep wrote:

pookie wrote:

yeah my comment was more on why didn't they make a stronger breather. This cheap little hose broke right at the t connection. Mine is extened all the way up towards the rear bumper, where it goes after that I don't know. I guess I will find out in a few. Any idea how much hose I need to run it up higher than stock? I have to stop and get the diff gasket so I was going to get the hose too, how long a piece do I need?

it goes up behind the gas tank. the most common place to route it is up along the gas tank filler tube... I bought about 10 feet and I wound up using 8 or 9 feet total for all three of my breathers.

back on topic .. thanks for the info ... I will need to re-do my breathers. Is there a post you used with a little how to or did you wing it?

The front differential breather is under the battery tray, it's attached to the top of one of the strut mounts. you should be able to feel it underthere and with a little force you can pull it off. Safest way is to pull out the battery tray though, but that's a PITA.

I did not have a trans breather because I have a manual trans... The hardest breather for me to do was my T-Case breather because it was well hidden on the side of the block between the driver side head and the starter (can't see it from the top of the engine, have to look underneith)

I'm not sure where the trans breather would be, but i've heard it runs along the trans dipstick, so try to take a look there.

You just need some 5/16ths fittings, 5/16ths hose clamps, 5/16ths hose, zip ties, and some (very little) creativity. I attached the T-Case breather and the front dif breather to the brake booster vacuum line. You may also want to get new breather vents depending on their condition (the T-Case breather vent is $4 and the rear-dif breather is $8 at my dealer. Didn't make sense to me so I just bought a few of the T-Case breathers).

pookie · **Joined:** Wed Feb 07, 2007 10:06 am **Posts:** 48

So I took the diff cover off expecting the worst, but everything looked ok. The oil was really dirty but that was about it. My buddy came over to help me out and he had the idea to jack up the rear and put it on jack stands to see if we could tell where the noise was coming from. So with the car jacked up it still really sounds like it is coming from the rear diff. We are up and down and all over that thing listening for the noise. Then my we put it in neutral, when we put it in neutral the the tires continue to spin.

(I know that isn't supposed to happen.) Almost like it isn't fully out of gear. Then just to check I put the transfer case in neutral. With the transfer case in neutral and the transmission in neutral the wheels don't spin. With the transmission in neutral and the tcase in 2wd the wheels spin. I have no idea what to check now or what the problem could be. I think the problem is in either the tranny or the tcase. But I don't know how to rule one out and focus on the other. Also when you shift from 4Lo to neutral it shifts fine. When you shift from neutral to 4fulltime it clunks and is sometimes hard to get from neutral to 4fulltime. (I'm hoping its the tcase since working on the Liberty auto tranny is so much $$$)I'm totally bummed but at least it's not a need to fix today so hopefully I can figure out what is wrong with it. It's tucked in the garage right now waiting to be fixed

Also the specs on the Jeep

2002 KJ
106K+ miles
Auto
3.7
45RFE (according to Haynes 02-03 had the 45RFE)
NV242 tcase ?? (I have full and part time 4 high, then into neutral and 4lo) not sure if it is this or the NV231.

Thanks

Weird humming noise...

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