humming noise r/f

[Glenn Peters]

98 blazer humming noise in r/f. goes away in 4 wheeldrive, I think !! Any common problem????

[hooker454]

One question does the humming sound resemble the noise heard when a truck has over sized tires on it driving down thee interstate. Ok two questions, does your humming go away when you turn the wheel in one direction an seem to get worse in the other, if so you just bougt yourself a new front hub assembly. the bearings are shot. the kicker is it a bit pricy, easy to acomplish by yourself in the driveway, if you need some detailed instuctions let me know, but buy the piece as a kit, I believe it the bearing hub assembly. Good Luck!

[Glenn Peters]

Originally Posted by hooker454

One question does the humming sound resemble the noise heard when a truck has over sized tires on it driving down thee interstate. Ok two questions, does your humming go away when you turn the wheel in one direction an seem to get worse in the other, if so you just bougt yourself a new front hub assembly. the bearings are shot. the kicker is it a bit pricy, easy to acomplish by yourself in the driveway, if you need some detailed instuctions let me know, but buy the piece as a kit, I believe it the bearing hub assembly. Good Luck!

Already replaced wheel bearing!! I'm an auto tech, heard something about 4wd problems, just wondering if any body knows of any common problem. Noise comes and goes, never there in 4wd! THANKS

[bm2]

hey i have an 89 blazer and i am hearing the same humming noise what is it and how can i get it to go away

[new2blazers]

I just bought a 99 blazer 4X4 2 months ago. 81000 miles, and last night going home, mine started making that grinding/humming noise in r/f at highway speed. If I sped up, it quieted. When I let off the accelerator, it got louder. When I slowed to turn onto my road, the noise slowed with speed and went away at about 20 mph and didn't make any more noise the rest of the way home. Any ideas would be greatly appreciated..

[Glenn Peters]

I'm the guy who originally posted this,I'm also an ase certified tech! The noise won't happen in 4wd or on the lift,it's not the wheel bearing! IT'S DRIVING ME NUTS!!!!!!!!!!!!! HELP!!!!!!!!!!!!!!!!

[beerman2003]

I just encountered the same problem with my 1996. Anyone find the solution yet? Seems like the front diff is not fully disengaging and the gears are making noise. Not sure which part is to blame?

[Glenn Peters]

OK Beerman is on the right track! I did a bit of road testing, speed at which noise is present varies(usually 50-55) seems to lessen if not totally stop if shifted into 4wd. When shifted back into 2wd noise returns, in a big way then lessens. I think there is an acctuator on the axle but have not checked it out!!! I would rather push my CHEVY, than drive a FORD !!!!!!!

[beerman2003]

Thanks for your help Glen. I changed the vacuum switch on the transfer case and that did it. Its on top of the case and has 3 vac lines plugged into it. Just take the lines off use a 7/8 wrench and change the switch. Its a little tough to get at but you can do it without taking anything apart. Cost $15 and fixed mine. There is a ball in the switch that opnes and closes allowing vacuum to be transfered bewtween the lines. Ive heard these balls stick and that will cause it to either not engage 4wd or in my case not disengage. I hope this helps ...let me know if you need anymore info on it.

[frankjc]

i wonder...mine didn't make the noise today.
i played with it a bit, switching in in and out of 4wd.
maybe it knocked the ball loose?
where did you get the part? used?

[Glenn Peters]

What part? I haven't done anything yet!!! I did however notice today that my 4wd didn't work( it snowed). The vacuum connecter fell off the switch on the transfer case,mabey that had something to do with it. Probably not, I'm not that luckly!!!! Mine blazer didn't or doesn't make the noise all the time either! If by some strange chance the vacuum issue resolved the problem, I'll let you know!!!!!

[autoengine]

I was having problems with 4wd engaging on my 97 Blazer. The lights would flash once and then stay in 2wd. I just changed the vacuum switch (the old one of which was really worn out). It is now stuck in 4wd. The lights on the dashboard switch no longer respond at all -- no clicking sound, don't even light up. Can anyone help?

[Glenn Peters]

Just for peace of mind take the vac switch out shift into 4wd and the back into 2wd and reinstall the switch. I'v seen them installed and stick, also check the ball on the switch while its out for sticking!!!

[autoengine]

I would try switching in into 4wd & back to 2wd with the switch off, but I can't even get the dashboard controls to respond anymore. I remember that there was another clicking sound lower in the dashboard when the controls did work. Is there another relay fuse or something else within the dash that might have shorted?

[Glenn Peters]

To be honest with you, I'm not sure exactly how the system works. Still waiting to recieve my FACTORY service manual. The click under the dash is a relay,I'll contact someone tomarrow and see if I can get the wiring diagram faxed to me and let you know. sound good???