Growling noise in 4x4 - axle or wheel bearing?

[DerekTheGreat]

Hi fellas,

Well, it's that time of year where 4x4 is handy and since I started using mine I noticed there is a growling noise coming from the front left of the truck whenever it is in 4x4 hi, starting around 20 mph. I don't hear it any other time and the noise isn't always there, sometimes it is when I decelerate, others when I accelerate and after a while, not at all. What do you think it is? I feel that if it was a wheel bearing I'd hear it all the time, 4x4 or not and especially on say a freeway on ramp...

 

[Biggershaft96]

id start out by making sure the bolts that hold the cv shaft to the diff are tight. mine losed up once and it didnt really sound bad but you could feel that something wasnt right when you put it in 4x4 so i threw some thread locker on all the bolts on both sides. if that checks out fine id jack the front up and check for play in the wheel bearing. after that id have a look at the front diff and t-case fluids

 

[RedLeader289]

My guess would be the CV joints. Had a similar issue in my jeep and that was the culprit.

 

[DerekTheGreat]

Thanks for the responses fellas. When I had the front up about 6 months ago to do the brakes there wasn't any play in the wheels. CV joints could be bad, they look old, maybe even original.

 

[Biggershaft96]

id pop the boots off and check out the greese, if it looks like crap might as well replace them.

 

[88shortbedchevy]

If it only occurs in 4wd, it might be your front driveshaft. Not sure how many miles are on your truck, but my K1500 Blazer's front diff needed rebuilt after 230k. Similar noise before the rebuild.

 

[DerekTheGreat]

Hmm. Yep, noise only in 4WD. Paid attention to it more yesterday and it's really only noticeable between 29-39mph, decelerating. Not much going on during acceleration, it's audible but not very. It's the deceleration it doesn't like, so perhaps the ring gear or pinion bearing? Great... As if this truck hasn't eaten enough from my pockets haha. "Doctor, how much longer has it got like this??"

Had a lot of fun with it last night though, we got our first real snow fall. Truck has 228k miles on it.

 

[88shortbedchevy]

How does it look? Have you checked the fluid level in it? I did mine for a number of reasons. On top of the noise, every seal was leaking on the thing.

 

[Biggershaft96]

Hmm. Yep, noise only in 4WD. Paid attention to it more yesterday and it's really only noticeable between 29-39mph, decelerating. Not much going on during acceleration, it's audible but not very. It's the deceleration it doesn't like, so perhaps the ring gear or pinion bearing? Great... As if this truck hasn't eaten enough from my pockets haha. "Doctor, how much longer has it got like this??"

Had a lot of fun with it last night though, we got our first real snow fall. Truck has 228k miles on it.

i replaced my front diff at 235ishk miles because of bad bearings. there are plenty of replacements out there for 50-150 bucks. if you have 3.42 gears you could have a craigslist replacement already pulled in no time. if you have 3.73s theyre out there but it takes some lookin. just make sure to spin it around a couple times by hand to make sure everything feels good. its also the perfect time to degrease your oil pan and put new u joints in your front driveshaft.

 

[redfishsc]

The rear end of my C1500 did this, turned out that the pinion and carrier bearings were getting really pitted.

Only heard it on deceleration