blefevre

Hello, I am new here! I just bought a 2000 Cherokee Sport and have a quick question.

There is a very loud humming noise that happens at certain speeds. Now at first most people would scream and yell about searching and coming up with a wheel bearing. Whenever I have wheel bearings go on my other cars it sounds a lot more high pitched and grindy then this noise is.

It happens lightly at around 30mph, then quiet until 60-65 where it is almost deafening. Then loud again at 70-75. It is a low bass sound that produces some vibration as well. The noise does not change with engine load or rpm's. It doesn't seem to change with different road conditions.

I normally wouldn't post about a problem like this but I wanted to know how loud Cherokee's are with slightly over sized tires (235/75R15 Michelin LTX M/S).

The car did come with service records from the past year (7,000 miles ago). There was a full inspection done and they said the wheel bearings were good. One of the U-joints was bad but it was also replaced. There was an alignment checked and a "thrust angle alignment" done when the new tires were put on 3,000 miles ago. All the brakes have been recently done as well. Tie rods were replaced.

Any thoughts? Are these tires just worn slightly off and really loud. I can hear the normal tire "whine" behind the loud humming noise so it is confusing me a bit.

Thanks for the help!

a1racer

do you drive with your windows cracked a little bit just barley open. sorry if this sounds stupid but if they are try rolling them all the way up if you have the windows cracked a bit it will make a similar noise to this

blefevre

It makes the noise with the windows up or down

MasterShakeXJ

could be a driveshaft, F/R might just need some grease. also, your tires could be making some noise if they are not properly balanced. try getting them balanced(if you havent already) and rotate them to see if that makes any difference.

blefevre

So I looked under the Jeep. Where exactly would I grease the front and rear drive shafts? I only noticed one "boot" on the rear but it looked more like a dust shield.

There was some play in both the front and rear drive shafts, it seemed like a normal amount of play. I drove again and put it in neutral this time and the noise doesn't change at all. Also if I floor it there is no change which leads me to believe nothings wrong with the drive shafts. I would however like to know where to grease.

Any other thoughts?

CHIF8008

is it more of a screach or a kinda hum?? cuz if you got bigger tires they will make alot of noise, with windows up or down

blefevre

Start humming, then make the lowest hum you can. It's like that just very loud with some vibrations. There is no grinding noise and no clunking. I checked all the U-joints and all were good. Only the front left had the slightest bit of play, maybe less then 1/2mm side to side. That one was replaced 7,000 miles ago.

COSXJFAN

Are your tires cupped??

blefevre

The tires seem just fine, they are 3,000 miles old. The car was aligned when they were put on. The previous owner said she had them rotated a few days before I bought it.

caged

does the humm go away if you let off the gas? if so, it's most likely your rear driveshaft u-joints. either the front or rear (on rear shaft). or rear pinion bearing. hope it's not that tho... it will usually humm when you get up to speed, your tires will start humming louder as you speed up. thats if your tires have an aggressive tread pattern?

blefevre

I can floor it, coast, be in neutral, and the noise will be the same. Nothing I can see is worn or messed up. I think I will have to take it to a shop when I have time.

REWSTER

is it lifted at all? with a 00 any lift you would need a T-case drop or sye, i dont have either and mine hums and vibrates all the time, with that tire you shouldnt have to much road noise if any

blefevre

I don't think it has a lift. The owner didn't mention it and it doesn't look lifted.

I did drive it a little bit in 4WD (only have part-time), I didn't have much time to test because there aren't too many straight roads here where I can go 65+. I noticed a slight "whine" at lower speeds, is that normal? The original hum was still there while coasting, and it appeared to be there when I would hit the gas but I didn't have too much room. Maybe my front diff and front drive shaft are bad

jblackmon421

I have the same tires on mine and I would say that if you are not used to driving a 4wd or an older Jeep for that matter it is the tires. It is a sound that you are not used to hearing in a car. Jeeps are not insulated as well.

blefevre

Do your tires get MUCH louder at 60mph or so? I can hear the loud wind/road noise before then, but the humming I get at select speeds seems way too loud for any vehicle.