Rear end makes an intermittent grinding sound at low speed

LASTFRONTIER

MEMBER
2003 CHEVROLET SILVERADO
5.3L
V8
4WD
AUTOMATIC
320,000 MILES

Intermittent "grinding" sound -- sort of like sandpaper, kind of like something is slipping maybe. Checked rear differential fluid from just the filler port. Didn't have a gasket yet, so will drain the old oil. But when I checked yesterday, it was low -- had to add 1.5 quarts to fill. Drove about 4 miles. Still makes the noise.
Changed the front differential oil.

5 Replies

SQM

MECHANIC
6,383 POSTS

Hello,

Did the fluid have any metal shavings?
Would it be possible to upload a video so we can hear the sound?

https://www.2carpros.com/articles/differential-service

If there was contamination like metal shavings in the fluid then that could be making the sound.
If the fluid it low it will be noisy as well.

Please let me know of any questions.
Thank you.

Image (Click to make bigger)

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Monday, September 13th, 2021 AT 12:14 PM

LASTFRONTIER

MEMBER
3 POSTS

Thank you! I didn't see any shavings on the rear differential plug, but I'm not sure if that one is magnetic. When my son gets home this evening, he'll check. I'll also video from the outside while he drives in a parking lot. That's the best way to hear the sound. It didn't work when I tried recording while driving with the window open. It may be tonight or tomorrow morning before I can get a video, depending on how late he works this evening.
The front differential fluid was black and the plug was full of metal bits. I read that when it's that bad, to change it each week or so with inexpensive fluid until it cleans up, and then use good synthetic oil.

Was this

answer

helpful?

Yes

No

Monday, September 13th, 2021 AT 12:19 PM

SQM

MECHANIC
6,383 POSTS

Yes, when the fluid is very dirty and have metal shavings it is a good idea to do few frequent changes to clean out the shavings (unless of course you take it apart).
Whenever you get around to it just upload the video.
Thank you.

Was this

answer

helpful?

Yes

No

Monday, September 13th, 2021 AT 12:25 PM

LASTFRONTIER