Jeep Grand Cherokee Help

BigBody79

BigBody79

Well-Known Member
Joined
Mar 30, 2005
Location
Lumberton
2009 Jeep Grand Cherokee Laredo
78,000 miles
3.7(?) auto awd
Michelin LTX M/S tires

Jeep has developed a pretty loud whine on the road. It started off sounding like the tires. But, we don’t put many miles on it and I don’t drive it much. But, it is suddenly way louder on the inside. It has the mud tire sound.

I heard the whine today in the yard when i took it to the shop to check some air pressures in the tires.

I’m thinking it is coming from the rear axle. How do I go about diagnosing which bearing or part the problem could be coming from? What would you check first?
 
Jack it up and start grabbing tires and pinion. See what's loose. None? Pull the diff cover and check gear and carrier bearings. Ok? Pull shafts and drop out carrier. If those are ok, look elsewhere.
 
No clunk.

I’m not sure drive shaft speed and wheel speed are different?

But it gets louder as you go faster.

It does sound different when you let off throttle. Really loud 70+

I wouldn’t call it a high pitch sound
 
Take note to whether it is at the same speed as the wheels are turning or faster (by say 3.73 times :) )
I bet you have worn/noisy pinion bearings.
 
Seems to follow wheel speed as opposed to driveshaft speed. I’m not an oscilloscope. Does not seem to change on/off throttle. Almost seems louder during braking. ESP BAS and traction control light came on yesterday on a longer trip. Jeep usually sees about 2 miles each way to work.
 
Put spectroid on your phone. Audio spectrum analyzer with peak and selectable identification of frequencies with a waterfall.

Screenshot_20190929-143705.png
 
Any play in the up/down side/side? That looks ok for backlash.. you could also put it on stands or a lift and run it in gear and stethoscope around..
 
No very tight in both of those directions.
Diff oil looked and smelled ok.
T case was grimy and covered in oil.
Have not opened diff cover.
 
Put in on the stands and ran it. Very exciting as it warmed up.

Couple things.
Most of the noise seemed to be coming from passenger rear rotor. So I investigated it. Looked pretty normal. Ran it with out the caliper on it. Noise seemed to go away. Put the caliper back on. It will not let the wheel turn at all. Only the other three wheels turn(Yay AWD). I am thinking that the caliper is not retracting correctly and thus rubbing causing a terrible noise.

But, with the caliper off I crawled underneath and there also seems to be a whirrrrrring sound coming from the middle of the driveshaft.

So, I'm going to throw some parts at the rear caliper and see if that helps. Then maybe move on to the driveshaft.
 
Almost certain that the noise is coming from the rear drive shaft. Come to find out this is a non-serviceable item. You have to replace the entire drive shaft to replace the u-joints. There are some replacements out there that are basically a custom drive shaft.
 
A piece of plastic tubing will substitute for a stethoscope
 
BigBody79 said:
Almost certain that the noise is coming from the rear drive shaft. Come to find out this is a non-serviceable item. You have to replace the entire drive shaft to replace the u-joints. There are some replacements out there that are basically a custom drive shaft.
Click to expand...
what is it? A CV jointed shaft? You should be able to remove it and check for slack and/or binding throughout range of motion..
 
No it is a regular u joint style shaft. This problem is common enough there are a few sellers that have premaid replacement shafts for sale on eBay
 
Well new used driveshaft did not help. I've thrown a few parts at this.

I did not put it back on jack stands and listen to it.

Still thinking the pinion or wheel bearings.
 
Update: took it to a guy. He says pinion bearing.

called ECGS 740ish to repair. Or get used axle for 150.

wife doesn’t want used parts. Driving me crazy
 
Back
Top