96 Blazer in 2WD Loud Howle

Ok..
This is becoming frustrating..
My Blazer when in 2wd mode there is a lour howl. When I switch to 4wd the howl goes away. This has been happening just recently did not do it when I got it.
Any help?? Is it the Consant Velocity? Bearings??
Thanks

Sounds like bearings.

Does it get louder when you turn right or left through a curve in the road?

I am not sure right now.. it is at the shop.. Would you think it is the inner or outer bearings?? Please say outer LOL.....
The only difference is that it stops completly when I switch to 4wd.

Could be the transfer case partially engaging the 4wd, since it goes
away after putting in 4wd.
Let us know what you find out from the shop...

Check the vacuum switch on the transfer case that engages the front axle.

Check the vacuum switch on the transfer case that engages the front axle.

I had a similar problem.After replacing the vacuum switch(about $32.00),it took care of the problem.Good luck!

Just curious- Where did you get the vacuum switch?

Just curious- Where did you get the vacuum switch?

Is the noise coming from the front axle area? If so, jack up the front end and turn the right side wheel. It could be that the right front axle is not fully engaging. Was the RF axle tube seal replaced? Improper installation can cause this.

Rickza,
I'm having the same 2wd howl problem too. I think it's from the passenger side axle area, but I'm not sure because it happens only at 48-56 mph.

As far as I know no axles have been replaced, but I'm not sure. My dad was in a hefty accident back when it was about new and it bent the passenger side frame a bit around the front wheel area. It was "computer straightened" (whatever that means) at a top quality shop. That axle could have been replaced at that time.

I'm pretty sure it's the vacuum switch. This seems like a common problem with these things. The tell tale trait (in my opinion) is that the noise goes away in 4wd.

However, I did just replace my pads and rotors and I did notice my wheels didn't spin all to freely. The wheel bearings did not feel loose, but it was not smooth rolling. I didn't expect it to be though because of all the 4wd stuff. Something may be partially engaged, but I'm not sure.

Rickza,
I'm having the same 2wd howl problem too. I think it's from the passenger side axle area, but I'm not sure because it happens only at 48-56 mph.

As far as I know no axles have been replaced, but I'm not sure. My dad was in a hefty accident back when it was about new and it bent the passenger side frame a bit around the front wheel area. It was "computer straightened" (whatever that means) at a top quality shop. That axle could have been replaced at that time.

I'm pretty sure it's the vacuum switch. This seems like a common problem with these things. The tell tale trait (in my opinion) is that the noise goes away in 4wd.

However, I did just replace my pads and rotors and I did notice my wheels didn't spin all to freely. The wheel bearings did not feel loose, but it was not smooth rolling. I didn't expect it to be though because of all the 4wd stuff. Something may be partially engaged, but I'm not sure.

Did you get a response or did you get the switch? From where??

If the vacuum switch isn't fully engaging the actuator, you can have this type of action. It can also be caused by a cable from the actuator to axle that is hanging up.
The easiest way to check is to have the vehicle running in park, parking brake applied, in 4X4 and jack up and support the right front. If the wheel turns, it's not engaged. If you hear a clicking noise when turning, it's only partially engaged. If that's the case, turn off the engine, and pull back on the actuator (under the battery) and see if the axle is engaged now. If still not, you have a stuck cable or problem in the axle tube.

Did you get a response or did you get the switch? From where??

I still have done nothing. It seems like it could be a wheel bearing, but I know for a fact it's been humming about the same for at least 15k miles. It seems like it could be a wheel bearing, but don't those keep getting worse and worse over time? This slight "throbbing" hum @ around 55mph has been happening for a long time.

When my wheel bearing went out, it went from a slight vibration to a loud hum and very bad vibration in about 5500 miles.
Here are the signs of a failing wheel bearing:
A vibration acompanied by a hum on the affected side
The vibration is felt at all speeds and changes with the vehicle speed.
It goes away while turning in one direction and gets worse while turning in the other.

It could be your front differential is'nt disengauging. Pull the Vacuume line off the accuater behind your battery at the T and give it a drive and see if the noise goes away.

Just curious- Where did you get the vacuum switch?

Chevy Dealer. Its about $38 in WA

Throbbing?

Sounds like a U-joint to me.....