Hey guys. I just picked up a 2000 z71 with about 108k for well under blue book value, and it runs and drives awesome. It has a brand new clutch, rebuilt rear end and t-case, and a few other little things. Really drives like a brand new truck.
Problem is: It's got this weird little transmission whine that is noticeable in 1st-3rd gears. It's really not that loud. If the radio is at a decent level it is not audible. But with the radio off it's enough for a passenger to ask what that noise is :sonicjay: I've done a bit of research and many say that their transmissions have whined since new, but others say it's not normal at all. The transmission shifts well, no grinding or anything like that.
So, anyone with some real experience with these transmissions, is it normal to have a little whine in these things?
sounds like you have some wear in the intermediate bearing between the input & main shafts? you can re shim the input bearing race as a temp fix but looseness on the side to side in the intermediate will always be there. you will reduce the noise a bunch by re shimming.
hmm. Well I honestly have no idea what that mean so it sounds a little beyond my capabilities. Since it is pretty quiet, is this something that will get worse real fast? Or progressively over time? The truck is my DD, and road trip vehicle to my parents house in Alpena, so I really just need to know if I can trust it.
first of all check the transmission fluid level. if it's low refill with the proper trans fluid. they take a special synthetic synchromesh fluid. GM part number 12345349. If the fluid is low or the wrong fluid was put in it at one time it can cause whining like you describe.
Alright well I crawled under there today and looked over everything. Trans has no leaks or anything like that, whole undercarriage is spotless including transmission. I found the bolt for the transmission fluid to fill or check it, but it's tucked in there pretty good. I think I'll run it up to a shop this week and have them change the fluid in it just for good measure. Can't hurt. I'm just hoping its not going to need a trans soon.
does the whine change with engine rpm or road speed? that will help pin which bearing is causing the noise. i have 3 NV3500 equipped vehicles and only my 95 S-10 had a slight whine in it, but that was due to low fluid level. it still whines alittle when cold but goes away when warm. i've determined the input bearing is the cause of the noise.
they usually go from whining to a rocks in a blender noise. if the oil level is good and clean i wouldn't worry about it. the synchros will probably go bad way before the bearing fails. most of those transmissions make some noise even when new. without actually being there to listen to it i can't say for sure if it's normal or indeed a bearing noise.
Thanks man, I really appreciate the help. I haven't even put plates on it so we'll see how it turns out when I start driving it every day. I got the thing for cheap so I can't complain too much, but I'll take it in and get the fluid changed anyway.
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