Hi All:
I'm having some trouble with my 4wd blazer. It has a loud roaring (Like oversize Tires) starting at about 25 mph. I have put the spare on both sides and test drove. Still making the same noise.
I jacked up each front wheel and spun them. The LF spun the drive shaft, The RF did at first, but seemed to disengage it when I rocked the tire forward and backward.
I rocked the front drive shaft and looked at the cv joints, the RF appears fine, but the LF has a little movement to it.
The wheel bearings seem fine.
I've also had problems with the HVAC. So I started tracing the Vacuum line and have found fluid in the line going to the Transfer Case. So I'm assuming that the switch will need changing also.
Is it possible that the switch is the culprit causing everything, by maybe trying to engage the front differential as I accelerate?
The noise in the front just started happening, but I've had HVAC trouble(not changing positions) for 6 months.
The noise is there whether in 4wd or 2wd.
I have checked the accuator under the battery and it appears to be engaging and disengaging just fine.
Any input on this will be greatly appreciated. Thank You and God Bless US All....John

 

I have dodged the raindrops and removed the vacuum switch from the transfer case.
The rubber hoses were not all the way down on the vacuum switch?? Does it matter? I would think it would, it has a line up pin on it (per se). Anyway, I'm going to change it out with a new one. I checked the switch, 2 ports hold no vacuum and the 3rd holds, but leaks off quickly. John

 

Hi stubby62, I have a 97 making roaring noise in the passenger floorboard area. Did you ever resolve your noise is and what did you find?
Thanks for any help.

 

Yes I found the problem.. Wheel hub was bad so I replaced and rides like a new one. Pretty simple to change. John

 

Yep...discovered the same thing myself. Took a chance and changed the right front hub. Voila'! Problem solved.
Cheers!!

 

was going to say hub assembly. You can tell ifs one of them becasue it will make more noise if you turn one way and less another

 

That's exactly what it was doing Andrew. Left turn or curve and it would quit.
Straight and curves to right it sounded like a prop plane.