Rear Differential? Help please

[BadOlHoe]

I have a 02 Tahoe that I bought with 134k in 2018, I now have 157 on her and I don't know the maintenance on her before me.

The symptoms are as follows.

I've always had a low growl sound when cruising 35-40 mph and the RPMs drop to 1000-1500 but goes away when I press the gas.
Also always had the clank noise when shifting into drive from park or reverse.
New is a squealing, or shearing sound when pressing the gas from a stop that has gotten louder over the last couple of months.

No loss of power, no grinding or clunking at all when turning which rules out joints.

Any help or suggestions would be appreciated thanks.

 

[mhaywoodcz]

Sounds like to me the universal joints in the main drive shaft are failing. Needle bearings are worn out, Clunk and squealing are symptoms I had on a previous vehicle. Have them checked or replace them...

 

[swathdiver]

I have a 02 Tahoe that I bought with 134k in 2018, I now have 157 on her and I don't know the maintenance on her before me.

The symptoms are as follows.

I've always had a low growl sound when cruising 35-40 mph and the RPMs drop to 1000-1500 but goes away when I press the gas.
Also always had the clank noise when shifting into drive from park or reverse.
New is a squealing, or shearing sound when pressing the gas from a stop that has gotten louder over the last couple of months.

No loss of power, no grinding or clunking at all when turning which rules out joints.

Any help or suggestions would be appreciated thanks.

Well, she's basically 20 years old now. Check the U-joints and consider dropping the differential cover pan and having a look inside. Course, when you do that you'll have to refill it with new fluid.

 

[rockola1971]

While some of your symptoms (sounds) could certainly be a rear axle or differential bearing gone bad. I highly doubt it is with the low miles that it is the rear axle and typical;ly axle bearings have a high pitch whine to them. I would first inspect the ujoints (they likely need replaced if original and if they have the clips then they arent original). Next I would inspect level and even drain checking for metal in the Tcase. Your growling can certainly be the rear output bearing of your Tcase. Inspect rear half of Tcase for the "GM Pump Rub" hole that will be just above centerline on passenger side of Tcase. Could also be the bearing in your planetary of your tranny also. This is of course assuming you have narrowed the sound down to be coming from the rear half of the Tahoe.

You dont want to have to find out the hard way that it is the Tcase output bearing. It could rip the Tcase apart and tear off the rear of your tranny while throwing the driveshaft down into the road. It wont be fun and it will be very expensive.

 

[BadOlHoe]

Thank you guys! It was in fact a u joint in the main driveshaft...that took care of the clank from park and the shearing sound under power.

I still cannot pinpoint the low rumble that cuts in and out at cruising speeds of about 35 when the RPMs are low.
Any suggestions?

 

[MassHoe04]

Just something to look at. It won't cost anything to crawl under and check to make sure nothing is touching where it shouldn't.

Can you rule out the possibility of any part of the exhaust making contact with the body, frame or skid plates along the line? Sometimes things shift out of place and move around after install of new exhaust system components. Loose clamps, bolts, or bent hangers can do that. Noises can generate at specific RPMs and nothing at other RPMs.

The exhaust clamps on my Jeep TJ had a tendency to work loose. The entire exhaust from header to tail pipe would pivot just a tiny bit. The heat shield on the catalytic converter would start clanging on the transfer case skid plate and drive me crazy. It would make noise at idle and be quiet the rest of the time.

Merry Christmas and Happy Holiday Season to ya'!

 

[Rocket Man]

I would start with fluid changes in the differential and if you’re 4wd, the transfer case and front differential. Transmission too, I would drop the pan and replace the filter and any fluid lost in that process. That gives you a chance to inspect for things in the fluids that shouldn’t be in there as well as a general sense of the health of these components.

 

[Mudsport96]

How do the tires look? Could be cupped or scalloped enough to make low speed noise. And as your speed increases wind noise and other harmonics can drown it out.