ok so heres what happened, in the past month or two i have noticed a progressivly louder humming sound , similar to that of if you were driving with an agressive tread on the tire. i thought it was the front left wheel bearing as it would be increasingly louder the faster you would travel. when you went into a dip on the road the noise would go louder, when you went over a bump and pressure was taken off the wheels the sound would become less loud. when turning to the left the noise would be less noisy and louder when turning to the right. also when traveling at speed the sound will become quiter the harder that you press on the brakes. i did just replace the front left wheel bearing which has made no effect on the level of the noise, and the old bearing seems to be rolling smooth. this sound is both in 4 and 2 wheel. there is a little bit of play in the steering wheel from side to side and the front tires to have 1/32 more wear on the inside of the tread with equal amounts over the middle and outside, assuming this is a result of suspension but could this possibly be to poor steering alignment? i have not taken off the skid plate to inspect the steering box but i have inspected the tie rod ends and there is no play, although when the vehicle is on the ground a clicking sound can be heard when turning the steering wheel back and forth behind the skid plate. steering box adjustment possibly?
from what i have read it does not sound like the passenger side front wheel bearing is worn but could this be a possiblitiy? i was going to switch the old bearing onto the right side as it seemed alright but i ran out of time running all over the city looking for a 36mm deep socket for the axle nut.

also the blazer does hesitate when starting off when i floor it, this is an intermittant problem, i replaced the fuel filter but has not corrected the problem, i am assuming this is going to be at the fuel pump/sender end of things as the fuel gauge has been jumping around and non functional for close to a year, a problem i also had with me 88 s15.
any ideas about the humming sound would be greatly appreciated.

 

I don`t have a 4wd blazer , but do they poss have carrier bearings on their driveshafts like the older 4wd trucks did and blazers???? Just thought i`d throw my 2 cents in...

 

yea i thought that it could be the bearings in the front differential, but then i got thrown off by the fact that the more downward pressure being applied the louder the noise which is what led me to believe it was the wheel bearings.

[IMG]local://upfiles/8548/AF0FBE32AD9A4B8FA66EDB14BB0C30D6.jpg[/IMG]

 

would the cv joints possibly make a similar sound to a worn wheel bearing? as far as i can think this is the only other thing that may be consistant with the varying loudness associated with the amount of downward pressure being applied, as the more pressure the more sag in the suspension the different angle in the cv joint.but if this was worn out would there not be play in the joint, and if the noise is affected by the braking would it not have a differnce in 4wd or the fact that it is still noisy when travelling in reverse?

 

Before you spend a lot of time and money, try rotating the tires front to rear. See if that changes the sound.
You could change the right front wheel bearing with the one you took out. I have been fooled a couple of times with changing the wrong front bearing.
Sometimes you swear it's the left front and it fools you by being the right front.
Keep us informed.

 

I had the same problem,changed front hubs,u joints,still the same so i put the blazer on jack stands put it in gear and listened for noise with a aluminum pipe,found out bad bearings in the rear differential.

 

thanks for the ideas, i did rotate the tires as well, when i find some time i will try swapping the old bearing with the other side. if to no prevail i have a contact at a shop and he will take a look at it for free and let me know of his advice, he owns a shop and used to own a blazer, works on all the fancy hot rods in the city. hopefully he will be able to help diagnose.

 

What bearings were bad in the rear axle? My 2000 blazer is making a weird sound almost like the caliper is froze? I check the brakes changed the u joints and sound is still there. If you think it is the bearings in the rear end how hard are they to change? Thanks fro any an all help. Rob