puzzled by new noise

[Oz-jeep]

Hi

I have a manual 2000 tj, when driving in 3rd 4th or 5th I have a noise like an old machine gun. The noise is constant no matter what gear I'm in but increases/decreases with relation to speed. If I ease off the throttle the noise stops. The noise also stops if I put it in 4hi. No noise when using 1st or 2nd or when out or gear or stationery. The noise appears to be coming from the L/H side of the jeep around the transmission or forward towards the front axle.
Any ideas please as I'm new to the jeep scene

Thanks

[David]

So you're saying that you only get it when in 4wd? Not to sound to condescending, but are you on pavement in 4wd?

[jfrabat]

I think he is getting it in 2Hi, but it goes away in 4Hi...

If this is the case, I would suspect the transfer case, but it baffles me even so because the parts that are moving for 2Hi are also moving in 4Hi. Maybe the shifter? Have you checked that the actuator is working properly? I guess it could be possible that the 4Hi is trying to engage, but then it is odd that there is no sound in 1st and 2nd...

	Transfer Case Mounted behind and driven by the vehicle transmission, the transfer case transmits power to the front and rear driveshafts in 4WD Jeep vehicles and offers high and low range.

[Bounty__Hunter]

A good method to narrow it down is to remove the front driveshaft and run the jeep, then remove the rear and reinstall the front and see if you can duplicate the sound.

[Oz-jeep]

Hi

No, I only get it in 2wd, the noise goes in 4hi

[Oz-jeep]

Hi

Yes, I'm puzzled why the noise speed is in relation to the engine and/or wheel speed. Also if I back off the throttle and coast the noise goes. Sounds like somethings in the drive train when under load

[mud4feet]

Originally Posted by Oz-jeep

Hi

Yes, I'm puzzled why the noise speed is in relation to the engine and/or wheel speed. Also if I back off the throttle and coast the noise goes. Sounds like somethings in the drive train when under load

I don't know.....ujoints maybe???? Have you checked them??

[Oz-jeep]

Hi

Both front u joints move slightly, not sure if it is the tolerance in the bearings or there should be no movement at all

[Bounty__Hunter]

There should be no movement at all.

[jonsolbe]

I agree, probably the u-joints. When you put it in 4 hi are you driving at highway speed like when in 2 hi? That may be why it seems to go away, that is if you're in 4 hi but driving in slow speed. If you're going to do U joints, etc, you may want to ask about adding a CV driveshaft if you're considering a lift in the near future:)

[dandoc]

Replace those u-joints and then report back to us on the noise or lack thereof. Regardless of the source of the noise, as Bounty said, there should be no loose movement at all in the u-joints.

[jfrabat]

X2 on the U joints; also, do you have any lift and if so, do you have a CV shaft? If you have lift and no CV shaft, what you hear could be some vibrations in the driveline, which you start hearing at high speed... Like jonsolbe said, I think the reason you are not hearing the sound in 4hi is because of driving speed, not because of 4hi/2hi.

Anyway, regardless if this is the source of your noise or not, like Bounty and dandoc said, you need to replace them, because it sounds like they are about to give up on you. They may well be the cause of your noise, but even if they are not, they need to be replaced.

[cweed]

I know this sounds like duh but my son just when through the same thing with his jeep and after going through all the testing of removing front drive shaft, then the rear with the front reinstalled we found the transfer case mounting bolts were loose. They looked tight but in fact had worked loose. We tighten up the bolts and the sound went away. We pulled to the transfer case to inspect it and found that when the bolts were loose it would push the transfer case back away from the gear mating surface and cause the same noise.

	Transfer Case Mounted behind and driven by the vehicle transmission, the transfer case transmits power to the front and rear driveshafts in 4WD Jeep vehicles and offers high and low range.

[dandoc]

oz-jeep, have you made any progress with determining the noise source and replacing the u-joints?