1997 Blazer 4-door, 4X4


I'm hoping that someone can help me diagnose this one. I have a mystery bearing in the front end of my Blazer that is growling/rumbling. I can't seem to figure out which bearing it is; although, when driving the vehicle, the sound seems to be coming from the front passenger side.

I tried lifting the wheels off the ground and spinning them by hand, checking for play, etc. I didn't find anything wrong that way. No wheel play, and no noise/vibration when spinning the hub.

Tonight it sounded really loud, and it had me worrying that the front diff was starting to go. Slow left turns make more noise than going straight or to the right--sometimes a LOT more noise. Just to see what happened, when I got close to home, I kicked it into 4-Hi. As soon as 4-Hi engaged, the sound went away. It came back faintly when I put it back into 2WD, but nowhere near what it was before.

Does this sound like a wheel bearing, axle bearing, or worse? How can I troubleshoot this to isolate the faulty bearing? And is it possible that a CV axle joint could be making this noise? Even if there is never any clunking coming from the axle?

 

Sounds like a CV Axel to me

 

sounds like the cv axle to me too . do it make the noise when you got it in 4wd? or just 2wd?

 

It only makes the noise in 2WD. Sometimes the noise is worse when turning LEFT, but is otherwise present in all driving conditions - directions, speeds, etc. The sound always goes away when I engage 4-Hi. So far, the noise stays away for a while after I put it back into 2WD.

 

Could be a frozen cable:
4wd Front Axle Clicking When in 2HI - Goes Away when in 4HI/4LO

 

Not the CV joint. Its the wheel bearing. Been there done that. You wont be able to hear or feel anything by spinning the wheel by hand. But once you get the bearing replaced you will be able to feel it when you turn the bearing in your hand.

When you engage 4 wheel drive it puts alittle tension in the driveline and actually does quiet the bearing. Believe it or not.

 

There is definitely no clicking going on. If anything, it sounds like a rough roller-type bearing; such as the wheel bearing assemblies on these things.

Does it make sense though, that the bearing noise would instantly go away when 4WD is selected if the problem was a wheel bearing? That would certainly be simpler than tracing all of the vacuum lines and switches for the 4WD system...

 

New symptom tonight....when I switched it into 4HI, I got a loud high pitched whirring noise. So now, the order of symptoms goes like this:

- rumbling noise from (apparently) front/right side while driving in 2HI
- put in Neutral, then shift into 4HI
- noise immediately stops, but high pitched whirring noise quickly becomes audible from under the vehicle
- shift back to DRIVE
- whirring noise remains throughout driving range, but seems louder when letting off of the gas pedal and coasting
- shift to Neutral, then shift back into 2HI
- shift to DRIVE, whirring noise still present--but goes away after resuming pressure on the gas pedal for no more than 3 or 4 seconds.

This has me wondering if something is seriously amiss with my transfer case. Please, does anyone have any ideas? Whatever it is, it's getting worse and I don't even drive the vehicle very often at this time of year...

 

there is also a bearing in your diff seperate from your hub that your half shaft sits in, could be that to. (hard to say though without being there)

 

Time to dig in and inspect some of the things brought up!