I have a 1995 4dr Blazer... Has the 3-button 4wd. When it is in park or neutral it runs quiet and normal, when i put it in any gear it starts humming louder as the RPMs increase then when it shifts into the next gear its quieter and gets louder again as RPMs increase... What can cause this? It is driving me nuts. It runs fine, shifts nice and smooth, the noise is just driving me nuts. I checked the trans fluid and it seemed fine, no burnt smell or discoloration. It did seem a little over full though, could it having too much fluid cause this?

Thanks!

 

Anyone?

 

First I would check the universal joints on the drive shafts. Even if they dont klunk when you put it in gear doesnt mean they are not dry and worn out. This can cause a few different kinds of sounds from a squeal to a hum . Just like a wheel bearing going bad or lack of grease. Quick easy test, just put it in neutral and spin the shafts by hand and see if any unusual noise comes from them. Can,t hurt to start there. this does not mean that there isn't a more serious problem.

 

I still have yet to find a solution, any one got any ideas?

 

A whine coming from the transmission can be a symptom of the front pump starting to go bad. Fluid level and condition really wont be able to tell you of this issue. only way is to have pressure checked and tested. A whine can also be the torque converter, sounds like you may need to have it looked at by a competent mechanic. And that is the key word competent in transmission repairs.