96 4x4 blazer grinding/slipping sound

[jakeyf08]

I notice when I take off from a stop there is a grinding/slipping noise coming from the rear end. Since this started happening I have also notice that when I let off the gas on the freeway the car starts vibrating. Also, I notice that when I then accelerate while at high speeds I can hear a little clunk. Could this be a U-joint starting to fail? I haven't crawled underneath and checked anything out yet and I am looking for some guidance on where to start looking!

[MT-2500]

Originally Posted by jakeyf08

I notice when I take off from a stop there is a grinding/slipping noise coming from the rear end. Since this started happening I have also notice that when I let off the gas on the freeway the car starts vibrating. Also, I notice that when I then accelerate while at high speeds I can hear a little clunk. Could this be a U-joint starting to fail? I haven't crawled underneath and checked anything out yet and I am looking for some guidance on where to start looking!

That covers a lot of teritory.

From transmission to rear end.

Describe the slipping noise in more detail.
Is it under heavy accceleteration or normal take off?

As far as things to check.
Start with fliud leves transmission/transpher case and rear end.
Check U joints and double joints and carrier berings and mounting.
Rear end slack and wheel bearings and brakes.
Does noise increase with MPH?

A good craw under there and have a look and feel around may point you in the right direction.

[jakeyf08]

I will be replacing the rear brakes this weekend so I can check most of it out while I am doing that. It makes the noise under heavy acceleration. The transmission was rebuilt about 10k miles ago so I am thinking about just dropping the pan and changing the filter right away, but before I do that I will check the fluid level. As for transfer case....the noise is very clearly coming from the rear half of the car...but I will check the fluid level on that right away. If I take it easy and don't give it a lot of gas it generally doesn't make the noise. It sounds like metal clicking or gears slipping. I had this same noise on a 89 bronco II and the after a couple weeks the drive shaft broke off the gear in the rear end.

Also when checking the U-joints whats the best way to tell if they are good?

I also wouldn't say that the noise increases with MPH because if I take off from a stop it will make the noise for the first 5-15 mph and the I only notice while on the freeway a little vibration when letting off the gas and then a clunk when accelerating again.

[MT-2500]

Originally Posted by jakeyf08

I will be replacing the rear brakes this weekend so I can check most of it out while I am doing that. It makes the noise under heavy acceleration. The transmission was rebuilt about 10k miles ago so I am thinking about just dropping the pan and changing the filter right away, but before I do that I will check the fluid level. As for transfer case....the noise is very clearly coming from the rear half of the car...but I will check the fluid level on that right away. If I take it easy and don't give it a lot of gas it generally doesn't make the noise. It sounds like metal clicking or gears slipping. I had this same noise on a 89 bronco II and the after a couple weeks the drive shaft broke off the gear in the rear end.

Also when checking the U-joints whats the best way to tell if they are good?

I also wouldn't say that the noise increases with MPH because if I take off from a stop it will make the noise for the first 5-15 mph and the I only notice while on the freeway a little vibration when letting off the gas and then a clunk when accelerating again.

ON CHECKING U JOINTS GIVE THE OLD LOOK AND FEEL AND LISTEN.

With it jacked up out of gear and brake off.
Check for no slack /play or loosness and feel cups after it has been run a while.
If loose or slack you have a bad one.
If any are hotter to the touch than orthers the you have a bad one.
Let us know what you find/see or feel under there.

[viggy58]

one way i check u-joints is to jack up the rear end, put it on stands. put the trans in neutral, and spin the back tires manually. you might be able to see/hear if the rear u-joint is frozen.

also, on a side note, make sure you service that transfer case at the proper intervals...

[jakeyf08]

Definitely going to check the transfer case to see if the fluid level is up. Is there a Drain plug on the bottom? and should I use something like Dexron III in it for a replacement fluid?

[MT-2500]

Originally Posted by jakeyf08

Definitely going to check the transfer case to see if the fluid level is up. Is there a Drain plug on the bottom? and should I use something like Dexron III in it for a replacement fluid?

Yes drain and fill plus both.
But.
Dexron 111 has gone BY BY.
No longer being made or sold.

Fluid type Depends on what transfer case you have.
Auto 4W or regular transfer case?

Gm makes fluid for both but is different stuff both.

[jakeyf08]

Regular transfer case.

[MT-2500]

Originally Posted by jakeyf08

Regular transfer case.

Check with your GM parts dealer.
They should have they should have some some standard transmission gear lube for it.

[jakeyf08]

I put the rear end on jack stands and noticed there is a lot of play in the rear u joint. I am going to replace it and see if the slack in the wheels is eliminated. While doing rear brakes i noticed the seal was leaking so I pulled the old seals out and replaced bearings as well. When i took the differential cover off the gear lube had a orangish brownish foam. Is this normal?

[MT-2500]

Originally Posted by jakeyf08

I put the rear end on jack stands and noticed there is a lot of play in the rear u joint. I am going to replace it and see if the slack in the wheels is eliminated. While doing rear brakes i noticed the seal was leaking so I pulled the old seals out and replaced bearings as well. When i took the differential cover off the gear lube had a orangish brownish foam. Is this normal?

No
May have water or rust in it.
Flush and clean old greese and replace.

[jakeyf08]

Replacing the rear u joint fixed the slack when putting it in park and the noise it was making. Thanks for all the help

[viggy58]

awesome!!! thanks for posting back with the fix.