Advice needed please

[mickferris]

Hello to all you good people.
I have just bought a jeep Cherokee 3.7 Limited 2002 and following the extensive test drive I paid up the cash and went on my merry way.
I thought I had done all the checks I could after following loads of advice on the net.
I just drove the car and noticed a small amount of noise from the rear. It has got louder the more I listen to it or maybe thats because I am listening to it.
It sounds like the rear differential? I had a 94 cherokee 4.0L which had the same problem. It is only at slow speed when I am turning the car. I am hoping it is due to the speed the wheels have to turn.
Is this a usual sound with this car or are we talkingh a serious expensive problem. I don't mind spending too much because the car is a stunner and was relatively inexpensive.
The car has done 60,000 miles with no obvious off road use. The car must at some point been used for towing due to the tow bar.
There isn't a problem putting it in and out of the range of 4X4 options and it runs like a dream.
Just the whirring and clicking noise form the back end
Any help or advice from you wise Jeep owners would be most appreciated.
If I need to give any further spec for the car please ask.
Thanks.
mick

[MagicRat]

Originally Posted by mickferris

It is only at slow speed when I am turning the car. I am hoping it is due to the speed the wheels have to turn.
Is this a usual sound with this car or are we talkingh a serious expensive problem.

The first question is: do you have a limited slip differential (LSD) on the rear axle of the vehicle?

To find out, jack up one rear wheel, parking brake off and trans in neutral. If the wheel in the air turns relatively freely, it is not an LSD. If it is very stiff to turn, it is.
Alternately, you can raise both rear wheels, trans in neutral, and spin one wheel. If the other rear wheel moves in the opposite direction, its not an LSD. If both spin in the same direction, it's an LSD.

An LSD will rumble in turns as you describe. The solution is to drain and refill the differential housing with gear oil explicitly made for use with an LSD. Allow the new fluid to work its way in to the mechanism before the rumble goes away. Sometimes driving in several slow speed figure-8's in a parking lot will do this.

If it is not an LSD, check the diff fluid level and condition. Try changing it and see if the rumble goes away, if the fluid is low or dirty. A fluid change is cheap to do.

if rumbling persists, you either have bad spider gears or bad wheel bearings. This repair cost is in the hundreds (not thousands) of dollars, so it is IMO not a particularly big deal.

[mickferris]

Hi MagicRat,
Thanks for your advice. I will check the diff to see the type it is and post back. A big weight off my mind that it won't be too expensive if it is what you say.
Fingers crossed. The car is great. I bought it a good distance form where I live so it was a bit of a risk even though it looks fantastic.
Went out in it again today for a spin and I am over the moon.
Not worried about the fuel consumption as it is only money.
I would rather have a smile on my face driving a great car than sat bored out of my skull in a economical nightmare.
Thanks for your help.
Mick