Howling noise from rear of 2000 XJ

Hi Everyone,

I recently bought this jeep with about 72000 miles on it. I started hearing this inconsistent howling (sounds like a low frequency feedback from a p.a.) noise during accelarating a couple of days ago. At first I thought it was the rear end but it also does it just a little when the jeep isn't moving. I can tap the gas with the tranny in park and you can hear the same sound but fainter.

Has anyone heard something like this before? Think it's some strange acoustic thing going on inside my jeep from the exhaust? Could it be the fuel pump? However, it's fairly loud when in drive and can be heard over the radio.

Greg

Are u sure it's not your speakers doing it. Turn your radio off and then try it, if you already haven't done this that is......

Does it have a hitch? If so, maybe the tailpipe is hitting it. Mine made some funky noises when it rubbed.
HTH

I have no hitch and it doesn't it with the radio off. Right now I'm 90% sure it's the exhaust. I might have to confirm it with my better half after work tonight. Good thing is that I got it to howl pretty loud in park at about 2-3000 rpm.

Man, I almost freaked out thinking it was the rear end. Funny how this stuff never pops when you test drive these things. Maybe I'm just hypersensitive because I just bought it and I'm thinking that everything is gonna start going to hell. That actually happened the last time I bought a car (88 xj)....cat was rattling, water pump went out, front wheel bearing, 4wd wasn't working because the vaccuum lines were clogged.

IF ITS only in the REAR, then youl have to check the fuel pump close, and you have spreakers in the back right? you will have to disconnect your stereo and thats all you can do unless its a rattle or something like that.

I had a 1991 YJ 4.oL and it started making a sound with the stereo, only i new it was through the speakers and the stock tape deck and i was not going to complain. The reason was [ It made this high pitch sound that sounded just like a Turbo ] I am seriuos, it was so awsome, and the higher the RPM, the louder the whistle got. IT really did sound like a turbo and at low RPMS when shifting from 2nd to 3rd it would sound like a Semi-truck. It was so weird, its like the jeep picked up a frequency from a truck and transmitted it through the stereo. It also only did it when a tape was in the deck, and when you started driving it on the Highway and around town for a while. Weird i must say

If it does it when you're not moving, it obviously isn't the axle. Next likely culprit would be the fuel pump. It's in the tank.

Will a fuel pump actually make a howling noise like that?

without starting it turn the key to the on position. the fuel pump should be audible for a second or so till it builds pressure, If thats the noise you are hearing its ok.

The fuel pump sounds normal when I turn the key without starting it. The howling noise when the gas pedal is depressed is a totally different sound.

Are you sure that its not coming from the front of the Jeep. So it does it when its moving and when its not. Is it a Manual or Auto? It does it when its in gear and when in its not. Could it not be a rattle? Howling, could you describe it a bit more?

Thanks

It's an auto trans. It does it in drive while it's moving and also in park. It's definitely coming from the very back such as the muffler or fuel pump.


The howling sound is a low to medium pitched howl. In some ways, it sounds like feedback coming from a guitar amp or p.a. ... Or it could be described as a howling wind through trees. The volume increases as you press the gas and then the sound goes away as the accelaration levels off. However, it's there even at idle but you can barely hear it. Also, the pitch doesn't change as get gets louder.

It's very strange....and sometimes a tad annoying. It's almost like the body of the jeep is amplifying the sound.

The only other thing I can think of is, one time my idler pulley went bad and i couldnt tell what it was cuz it wouldnt do it at idle, and it sounded farther back than it was,
just for kicks rev it from under the hood and listen

It sounds like someone blowing into a jug while playing hillybilly music but without the hillbilly music.


My fiancee said she's heard this before in her folk's later model Explorers and to her it just sounds like a "big vehicle" sound. Anyway, I can't hear it outside of the vehicle at all...only inside and in THE BACK of the vehicle (it's DEFINITELY NOT coming from anywhere close to the front half of the jeep). Now I'm pretty damn sure it's just some weird acoustic thing going on from the exhaust.

Thanks for everyone's help!

There is a thin metal heat shield between the tailpipe & the gas tank. Maybe there?

It could be that...hard to tell since I can't hear it from the outside. I think that's a good sign that it's nothing mechanical. The exhaust will probably need to be replaced in a couple of years anyway and that might take care of it.

what kind of muffler does it have and what size is the pipe? If either are aftermarket you will hear the exhaust running through the pipe. No big deal at all.

It looks like the original exhaust by how old it looks.

you wont have to replace your exaust unless you rip it off cause its magnetic stanless you might have to replace it in 15 years tho

i would say it is from the radio .put you ear up to the speaker as she revs it and see if it's from the speakers.if you can't hear it outside i would find it hard to be the exhaust.my guess is it's the noise supressor from the coil .causing electrical feed back in the radio it can still do it with the radio off sometimes.

Apparently there's a tech service bulletin out on this. I forgot to mention that this "howling" occurs at 1700, 2500, and 3000 rpms. Looks like I gotta replace the muffler and tailpipe or just learn to live with it.

NO: 11-01-00 Rev. A
SUBJECT: 1700 -2400 RPM Exhaust Drone
DATE: Aug. 4, 2000
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 11-01-00, DATED JULY 21,
2000, WHICH SHOULD BE REMOVED FROM YOUR FILES. THE REVISIONS ARE HIGHLIGHTED WITH
ASTERISKS AND INCLUDE A REVISED PART NUMBER.

OVERVIEW:
This bulletin involves installing a revised muffler/tailpipe assembly
containing an end cap reinforcement.

SYMPTOM/CONDITION:
Some vehicles may exhibit a droning sound coming from the exhaust system with
the engine operating between 1700 and 2400-RPM. This sound can be heard either
in neutral or in gear while driving.

DIAGNOSIS:
With the engine at operating temperature and the transmission in park, raise
the engine speed to 1700 RPM and slowly raise it further to 2400 RPM. If the
sound is present and there are no other related conditions such as grounded
engine/transmission supports or exhaust system components, perform the Repair
Procedure.

PARTS REQUIRED:
Qty Part No. Description
1 05019872AA Muffler/tailpipe - (Non Flanged Exhaust - MDH 0116XX and prior)
1 **52101262AH** Muffler/tailpipe - (Flanged Exhaust - MDH 0117XX and later)


REPAIR PROCEDURE:
Using the procedures outlined in the 2000 Cherokee Service Manual, publication
number 81-370-0046, section 11 page 6, remove the original muffler and tailpipe
assembly and install the appropriate assembly listed above.

POLICY:
Reimbursable within the provisions of the warranty.

TIME ALLOWANCE:
Labor Op. No. Description Time
11-30-01-95 Muffler - Replace - Flanged Exhaust 0.3 Hrs.
11-30-01-96 Muffler - Replace - Non-flanged Exhaust 0.5 Hrs.