I just joined to ask you all about this problem. So if you see newbie stuff you know why.

My Blazer is a 1998 xlt and I have a bothersome sound I can't isolate. It sounds very much like just plain road noise, like knobby tires would do at slow speeds. Kind of a deep hum.

It is constant, never varies in pitch or volume no matter what I do. It's not tires because I had it before I put on new tires and that never changed it a bit. It doesn't respond in any way to turning right or left, braking, or accelerating. The oddest thing is that it does not change pitch with changing speed or rpm. It can be heard down almost to a stop, but is not there, that I can hear, while stopped. Being in neutral coasting doesn't change it at all. Being in 4 high makes no difference. I couldn't tell in 4 low because of the rpm sound level.

I have read some posts about similar sounds, some even having to do with steering, but nothing seemed possible with those symptoms I gave. I can't tell any direction either; it just seems "ambient" in the car.

 

Driveshaft out of balance? Worn U joint(s)? Rear wheel bearing? Pinion bearing or other differential problem? Engine or transmission mount worn?

 

I'm new. I put this problem in 'sights and sounds' and only got one comment. He gave me some things to think about but I have just about thought this to death already. So I'll post it here.

My Blazer is a 1998 xlt and I have a bothersome sound I can't isolate. Not real loud but intolerable because it shouldn't be there. It sounds very much like just plain road/tire noise, kind of a deep hum. It had it when I got it at 170k. Beautiful car, red, always garaged.

It is constant, never varies in pitch or volume no matter what I do. It's not tires because I had the same sound before I put on new tires and that never changed it a bit. What a disappointment that was. It doesn't respond in any way to turning right or left, braking, or accelerating. The oddest thing is that it does not change pitch with changing speed or rpm. I can hear it down almost to a stop, but not while stopped. Shifting to neutral to coasting along, or driving in 4 high makes any difference. The steady frequency would seem to rule out all rotating parts.

I have read some posts about similar sounds, some even having to do with steering. I can't tell any direction either; it just seems "ambient" in the car. Would a wheel bearing rumble steady like that, fast or slow?

 

Wheel bearing I had the same issue Doesn't matter what you do the tire still needs to move forward in 4 high or low fast or slow ..you might find alittle play in the wheel ( mine moves from 12'oclock to 1 o'clock ) before the truck moves left or right. Took it to a shop knowing it was the wheel bearing and the mech always does a test drive and put it up on a hoist and confirmed it was the wheel bearing ...The new ones go on tomorrow

 

moosehauler05'blaz,
Thank you for that reply. I may need to get it on a lift to help with diagnosing it as you did. I just can't make myself replace parts on suspicion alone. I wiggled the wheels top-bottom, right-left, and spun them while listening. All seemed fine but I'm old and worthless now so maybe I didn't get violent enough. Disk brakes just barely touch so I can't get a free spin on the wheels for listening. I hope it is a wheel bearing and not some drive train pain. I'll let you know if I get it solved.

 

Just did a drive home from the shop after the new bearings drives quiet and the steering seems 90% better. Smaller sort of play in the wheel the road noise vrr vrr vrrr vrr is gone

 

Glad to hear the bearings did it. I have steering play too but I can watch and see that the wear is in the box. I tweaked the adjustment a little but I dare not go far enough to fix it. I learned the lesson of doing that when I was a kid with an old worn out '39 chevy. I might just sell this Blazer. It is surely the best looking '98 there is anywhere. Enjoy that silence, wish I could.

 

See the special man hook.He knows it all.You have a problem he`ll guide you in that right direction.Just saying!

 

toocute350,
got the message. Actually, a "captain hook" has been in touch already. I imagine he is the hook you referred to. I firmly believe in hearing from the voice of experience. I'm too old (lazy) to do any unnecessary work so I'm trying to rifle shoot the trouble. When I got my Blazer I knew I was at risk because of the infamous intake manifold gasket. Sure enough then, found water in the oil, no oil in the water, engine running smooth as can be. I fixed that myself.

I'm leaning toward wheel bearings for the sound due to moosehauler telling me his made a sound like v r r v r r v r r. That is my sound, only vrrrrrrrrrrr.

I'm also having an intermittent failure of my hvac fan to run. Oh I wish I could find a schematic. The ones I find are so pixelated I can't read them at all. None. Auto Zone deems not to show that drawing. Fun and frustrating games- thanks for posting a response.

 

Factory electrical schematics can be found in an AlldataDiy subscription or of course the factory manuals. I find both are useful.

This is an example of for a 2001, but there are many more pages for HVAC electrical.