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Chevrolet Express
Platform: GMT Van

whine/whistle over 50MPH

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Old Apr 29, 2014 | 10:46 PM
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Default whine/whistle over 50MPH

1993 Chevrolet G20, 6 cylinder, short wheel base.

I'm almost positive it's coming from the drive shaft and/or transaxle. I have some amount of leakage where the shaft exits the transmission as well as where it enters the transaxle. The van has whistled softly ever since I purchased it less than 30k miles ago. It hasn't gotten worse, but it's still there. What I'm looking for is other possibilities to cross out before I finally go through with replacing the whole damn rear end. It's been delegated to weekender status since I realized it was probably the shaft/transaxle whining, I'm afraid to take it too far for fear of creating too much heat if things are bad back there and ending up with a real mess on my hands.

I'm going to take a video of the whining in the AM, hopefully my camera's audio input is decent enough that it'll pick up on the sound.
Attached Thumbnails whine/whistle over 50MPH-556162_4861815545022_2049352938_n.jpg  
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Old Apr 29, 2014 | 11:51 PM
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Differential. Not transaxle.
usually a worn diff will whine, or make a grr sound. How long since the fluid was changed? If its really black, then it should have been changed ages ago.
See if the fluid change helps, but if the ring and pinion are worn, then nothing will fix it.
The fluid loss at the front seal could just mean worn seals. The ones at the drums are likely leaking too.
How many miles on the van?
It could also be a tranny issue. How long since that fluid was changed?
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Old Apr 30, 2014 | 1:30 PM
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Default do you have a good mechanic

these older vans are fairly straight forward. take it to the shop to have them figure out whats up. then you can decide if ots something you can handle or bite the bullet and let them.
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Old Apr 30, 2014 | 3:18 PM
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Differential. Not transaxle.
Thanks.

usually a worn diff will whine, or make a grr sound.
It's definitely whining, but no grrring (yet!)

How long since the fluid was changed? If its really black, then it should have been changed ages ago.
I replaced the fluid around a year ago when I replaced the rear axle seals and bearings. I didn't see that anything looked bad, but I didn't inspect it as closely as I probably should have.

See if the fluid change helps, but if the ring and pinion are worn, then nothing will fix it. The fluid loss at the front seal could just mean worn seals. The ones at the drums are likely leaking too. How many miles on the van?
130,000

It could also be a tranny issue. How long since that fluid was changed?
I'd have to check, but I know it's been a while and probably due. The second to last owner took meticulous care of the van and kept records since purchase. I doubt the last owner had it replaced. She only had it for a few years (think she put around 30k on the van) but didn't take it to the shop nearly as often.

I currently have the van on the lift to replace the winter tread so I took a couple pics. I should still have a video up tonight.
Attached Thumbnails whine/whistle over 50MPH-p1070975.jpg   whine/whistle over 50MPH-p1070974.jpg  

Last edited by the68; Apr 30, 2014 at 3:30 PM.
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Old Apr 30, 2014 | 5:04 PM
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I took a video. The camera really picked up on the whirring, so I'm currently uploading it to my youtube account. I'll post it when I get back on tonight, I have to switch vehicles now and do some routine maintenance on the motorcycle.
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Old Apr 30, 2014 | 8:23 PM
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You replaced the axle bearings? Did you re and re the ring and pinion to do that? I ask because differentials are notorious for being noisy after a rebuild. They are hard to set up the clearances just right....
The oil at the back of the tranny is dark. Are you sure its not engine oil? Taste test time.....lol
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Old Apr 30, 2014 | 9:33 PM
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You replaced the axle bearings? Did you re and re the ring and pinion to do that?
I ask because differentials are notorious for being noisy after a rebuild. They are hard to set up the clearances just right....
I pulled both axles, removed and replaced the bearings and seals, lubed and put everything back together. I checked the ring and pinion to see how it looked and I didn't notice anything like excessive wear, but I didn't replace them. I should probably look in that stack of records to see if a rebuild was done before I purchased it, but I wonder if the noisiness would still persist after the 20K I've put on it in such a case?

I did check the transmission fluid. It was just to level and relatively clean.


The oil at the back of the tranny is dark. Are you sure its not engine oil? Taste test time.....lol
I should check that, though I'm pretty sure it's tranny fluid. I don't seem to lose engine oil, but I do remember having to top the tranny fluid off when I first got the van. It's stayed pretty level since with minimal loss. I ran a paintball field for years where we used transmission fluid to lube the markers, so I can definitely do a smell test. :P

Here's the youtube video. The video itself is irrelevant. It's almost 6 minutes long and I don't expect anyone to sit through all of that; you can hear the whirring most clearly at 3:10 and on.

https://www.youtube.com/watch?v=ysTz...ature=youtu.be

When the engine has a load on it (going uphill) at low gear you can't really hear it, but once you get into higher gear at higher speeds it starts whirring. I've found it is loudest on the decel and when coasting.



https://www.youtube.com/watch?v=ysTz...ature=youtu.be

Last edited by the68; Apr 30, 2014 at 9:47 PM.
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Old May 1, 2014 | 1:19 AM
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Yup. My last van sounded like that. The dummy PO never changed the diff fluid and it was jet black. New fluid helped a bit, but I mostly had to live with it. Once the gears start that whine, its had to fix. Maybe keep an eye out for an axle at a wrecker, and just swap it.
My dad told me in the old days they used to put sawdust in the diff to quiet them down.....lol
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Old May 1, 2014 | 6:43 AM
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Originally Posted by canucklehead
Yup. My last van sounded like that. The dummy PO never changed the diff fluid and it was jet black. New fluid helped a bit, but I mostly had to live with it. Once the gears start that whine, its had to fix. Maybe keep an eye out for an axle at a wrecker, and just swap it.
My dad told me in the old days they used to put sawdust in the diff to quiet them down.....lol
Come to think of it when I replaced the seals and bearings the diff fluid looked as though it had probably never been changed, and there is nothing in the records saying that it was ever done; the first owner (I am the third) took it to the same garage over and over again for the piddly-est stuff that I would do or fix myself, and the second owner pretty much neglected it. Both were apparently not mechanically inclined. I've got an ad up on CL for a donor vehicle, but no hits yet. I'm probably gonna have to start calling around to the local yards to see what I can come up with. Thanks for all your help canucklehead!

lol yah, my brother (who is more mechanically inclined than myself) told me the same thing about the sawdust. He said jerks will do it to a vehicle they're planning to sell soon to save them the trouble of fixing it for the purpose of the sale. smh
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