drivetrain noise - grinding

2000 Cherokee with np231 4.0.

Get a slight noise when slowing down in gear. Still happens when hitting brakes. When in neutral it goes away. Noise sounds like
a whoop whoop noise.

Now I just put it in 4wd and i get a grinding From the front, not loud and seems to happen when coasting. Seems to come from the front passenger.

I am thinking bearings are toast in pass front.

Any way to find out 100% before I throw 100 bucks at it?

Also when greasing the fittings on the car what is the proper technique? Slow and then stop when the grease coming out is clean? There are no seals that I grease that are closed and I will pop them if overfilled?

Thanks in advance.

kellen said:

2000 Cherokee with np231 4.0.

Get a slight noise when slowing down in gear. Still happens when hitting brakes. When in neutral it goes away. Noise sounds like
a whoop whoop noise.

Now I just put it in 4wd and i get a grinding From the front, not loud and seems to happen when coasting. Seems to come from the front passenger.

I am thinking bearings are toast in pass front.

Any way to find out 100% before I throw 100 bucks at it?

Also when greasing the fittings on the car what is the proper technique? Slow and then stop when the grease coming out is clean? There are no seals that I grease that are closed and I will pop them if overfilled?

Thanks in advance.

Click to expand...

On flat level ground
Block the tires, put shifter in neutral, 4x4 lever in 2wd.
Go under the truck and rotate the driveshafts to see if there is ANY slop in the u joints at all.

Driveshaft and steering joints will chirp when they are dry.

If they are just dry try to grease them if they have the fitting, if they are loose they must be replaced!

As for the wheel bearings..... block the rear wheels, jack up the front and see if you can move the very top of the tire in and out of the wheel well.
If there is ANY movement, have someone move the wheel while you watch the back side from underneath. It could be the bearing or ball joints if the wheel moves.

The front axle shafts can be inspected at any time with out lifting the vehicle.
Grab the ears of the inside shaft and see if it will work back and fourth. Make sure its in 2wd.

I am willing to bet that it is your front axle U joints. They would be most effected by deceleration.

As for the grease fittings... Just pump slow and if you grease regularly, you only need to add till it JUST starts to come out. If you have never greased it before... then it would not hurt to pump and flush it till it comes out clean.

You are NOT going to blow any seals. U-joints are more picky, you don't want to force too much grease through them.

How's the brakes?

Hope this helps,
XJR

i have the same deal going on; unless i pull my rear driveshaft.... and the u-joints are brand new in that thing now - made no difference. maybe we have the same problem, maybe completely different ones; just through id throw this in here in case it helps though.

Do the 2000 cherokees have c clips in the diff I have to remove to get off the half shafts (axle shafts, prop shafts, whatever)?

Thanks,

Kellen

kellen said:

Do the 2000 cherokees have c clips in the diff I have to remove to get off the half shafts (axle shafts, prop shafts, whatever)?

Thanks,

Kellen

Click to expand...

Nevermind, was confused on the c clip explanation.

But why would the noise only happen in 4WD? Will check the front when in the air.

4wd noise only happens under acceleration. Sounds like a metal on metal sound. Changes with speed. Seems to be front pass side making the noise.

yeah just clean out the old grease and keep putting in grease with a grease gun in the zerk fittings till clean grease comes out the joints.

So just got done taking a good look at everything.

The u-joints seem to be in good condition. No play in the shafts, only can rotate it like 10 degrees. Everything is super tight.

Also jacked up the front and spun each one by hand. No noise and couldn't feel any vibration on the coil spring.

Tried to jack the tire up and down, side to side to check for bearings. No play, tight as a drum.

Any other ideas?

good way to check the front u-joints in the axle? I just took a quick look at them and tried to move them around, seemed tight to me.