04 trailblazer grinding

[Blindboy]

Hello all,
I have read many threads on this issue, but none seem to help my situation.
04TB 4WD. when i reach about 35MPH the grinding noise begins. It gets worse as i begin to slow down, and finally stops as the vehicle comes to a complete stop. Based on the threads here, i replaced the right wheel hub assy with a Timken, but the problem persists. If i switch to 4WD the problem stops. I have not yet tried to drive only in 4WD, But may try that next. The rotors are pretty crusty, but i dont know why that would make such a horrid noise. The CV boots appear perfect. Any help is greatly appreciated, i just can't afford a mechanic right now.

 

[The_Roadie]

You can't drive around in 4HI mode except as a short-term test, but it's very unusual that noises get lessened in that mode.

How many miles on the truck, and when was the last time you checked fluid levels and replaced the fluids in the transfer case and the front differential?

When you replaced the right hub, was it because it made less noise in a right hand turn? I once changed the wrong hub because of the noise being opposite of what I expected. It can happen.

 

[Blindboy]

Thank you for responding.
86K miles, never replaced trans or diff fluid. I've just been trusting the mechanic to tell me when. I will be checking the trans fluid today. Also never checked or changed transfer case.
I changed the right hub based on a sense that the noise was coming from that side, but I have been wondering if it could be the left side, and the noise was just bouncing around. I suppose it could even be both of them. I did get about 10 miles of driving in after replacing the right side hub before the noise began agaon. I didn't really notice a difference when turning. It just gets worse and louder as i slow down. I've just been too scared to keep driving when it happens. It really sounds horrible

 

[The_Roadie]

Transfer case needs to be done every 50K. In the Owner's Manual. Very important. Please get the level checked at the very least. A mechanic may be the only way to find the noise on a lift while it's running.

 

[Blindboy]

Will do. Updates to follow.

 

[Blindboy]

Had it out for a drive today. Grinding started at 20mph, just as I hit the brakes. made it up to 25 and it began again so I slowed and tried some turns. right turn and left turn had no effect on sound. After stopping, it then began again at 27mph. Speeding up did not effect the noise. Next time it began at 30. This was all in the first ten minutes. Finally, i drove around for about an hour and it never returned.
Roadie, you mentioned the transfer case, but how would that affect anything if I am not using 4WD?

 

[The_Roadie]

The transfer case has a LOT of moving parts inside that need their fluid. Bearings and seals, plus the clutch plates are ready to be engaged and contamination can make them grabby or sticky when you engage A4WD or 4HI mode during troubleshooting. Same for the front differential. Just because there's not a lot of torque flowing through it in 2HI mode, there are still a lot of moving parts, same as the CV shafts.

 

[eman]

Why did you change your right hub assembly? Was the noise coming from that side? I ask because I replaced both hub assemblies during last summer and afterwards noticed a grinding coming for the right side. I was thinking it was a bad hub from the factory but it turned out to be shot bearings/seal in the 4wd disconnect. The cv axle attached to the disconnect assembly spins all the time in 2wd and 4wd and it seems like the bearing/seal tends to fail pretty commonly. However, I was having problems with my 4x4 only working periodically.
if the sound is coming from the front passenger side it may be worth checking out that assembly...