Hi everyone, I have a weird problem with my 98 4x4 LT Blazer... I clearly hear a "grinding, rubbing" kinda sound coming from the right side, passenger side, front axle when I am in 2Hi, but it goes away simply by putting it in 4Hi... I can feel it engaging into all 3 modes, 2Hi, 4Hi and 4Lo... Any ideas or suggestions would be greatly appreciated! Finally, if I just choose 2 drive it in 4Hi will that hurt the vehicle over the long term? I only drive it 2 and from work, about 3 miles a day total 5 days a week... Thanks in advance for any info or advice!

 

It could be the shift collar not fully releasing in 2HI thereby causing the sound you hear. Putting it in any of the 4WD positions pulls the collar all the way on so it completely engages.
Could be the return spring on the shift collar, could be the front axle actuator is sticking and not completely releasing the shift collar. Just two thoughts of problems, there are more.

Put the right front wheel up in the air, put it in 2hi start the engine in PARK and rotate the right front wheel. It should move freely, no binding, no sounds. If you hear a clicking, could be wheel bearing or the shift collar did not fully release and it is grinding. That sound would come from around the pumpkin. You should also feel it in the tire when you rotate it.

Then put it in 4HI with the motor running and in PARK. Rotate the right front wheel, you shouldn't be able to if if is working properly. It should lock. If it makes the same noises as above, same problems.
I wouldn't drive it until it is fixed. If it is the shift collar gear, the metal filings are going to wind up in the pumpkin and destroy it. If it is the wheel bearing it could seize up and cause an accident. If it turns out to be the front axle actuator and/or cable, that is pretty easy to fix.

Goodluck

Bill

 

Yes, plus note that the front diff components can turn even with them supposedly disengaged due to drag caused by oil. So dont overlook components that 'shouldn't turn when not in 4X

 

4HI is not to be recommended. Blazers have no differential in the middle of the drivetrain to equalize between front and rear.
You can drive this way but really should avoid any tight turns. It puts enormous strain on the drivetrain, eventually braking compononents.
It is really only meant for slippery surfaces.

When doing so on hard good grip pavement and doing turns sometimes you can feel it "hop" as it tries to equalize the different turn radii between front and rear axle.

If I have to I only turn the steering wheel a maximum of 180 degrees (half a turn), i.e. when pulling a trailer out of the muck onto the road or so. You should be fine on gravel or unpaved to do tighter turns.

 

I finally had time today 2 do the suggestion of jacking up the front passenger side tire and found something strange 2 me... With the motor running and in park, I spun the wheel in 2Hi, sound was there spinning it forward but no sound what so ever when I spun it backwards... It woulnd not spin in either direction in 4Hi or 4Lo... I was also told by a guy at Autozone and Advance auto parts that driving it in 4Hi is not recomended long term but it shouldn't really damage anything only driving it as little as I do... I only put 3 miles on it a day, 5 days a week for a total of 15 miles... I was also told it might be the transfer case switch, possibly the transfer case itself but more than likely just the switch???

 

Based on the previous post, the only thing the Transfer Case Switch does is to apply vacuum to the front axle actuator. That's it. It makes no sounds whatsoever.
If you think the switch is bad, check the vacuum on the front axle actuator with the TC in 2HI and the engine running, tranny in PARK. There should be no vacuum. If there IS, the switch is bad because it is leaking vacuum through the switch. And in 4WD there should be full vacuum..

As to driving with that noise in 2HI. If the switch is bad and applying partial vacuum to the front axle actuator, it is partially engaging the front axle. It is causing the shift collar to partially engage the collar between the two front axle gears causing them to grind. That is the sound you hear. Eventually the gear on the axle side will grind down to a point where the axle will not engage in 4WD at all and will through metal shavings into the differential oil blow up your pumpkin.
I had to rebuild my front axle for the same symptoms. The Transfer Case Switch, front axle actuator and its cable, the entire front axle disconnect system and all the vacuum hoses.

If it fails again, I will do the Bravada Axle Swap and be done with it. This front axle disconnect system is not a good system and is to problematic.


Bill

 

I am curious about the "Bravada Axle Swap"..... Reason I ask is someone my wife works with has a Bravada, not sure the year, for sale pretty cheap, $500 bucks I think she said???

 

You just remove the intermediate axle shaft and all of the front disconnect parts and replace it with the Bravada shaft and a cover to cover up the hole for the shift collar.
It has to be for the slip on CV axles only and the Bravada shaft has to be from the AWD version..

Bill

 

Finally got 2 the bottom of the problem... I finally decided 2 replace the 3 button switch on the dash and problem solved! I am now back in 2 Hi with no further strange sounds of any kind... All ranges are working as they should as of now.