Strange Noise Where There Shouldn't Be One

[Va6622]

I have a 1989 Silverado standard cab with a 5.7 350 automatic. The truck has always been quiet, (no weird noises). Recently my speedometer stopped working and after some research I replaced the vehicle speed sensor on the tale end of the transmission. The sensor can only go in one way as far as I can tell and is attached by one bolt. As soon as I put the new sensor in and started to drive the truck there was a loud, whining noise coming from under the truck. I thought it was too much of a coincidence so I jacked up the rear end enough so that the wheels were off the ground and got someone to put the truck in drive and reverse. I got under the truck and sure enough the noise is right where I put the new sensor in. It was a off brand sensor. So I replaced that one with an ACDelco sensor. No change in the noise. Any help greatly appreciated. I don't

You must be registered for see images attach

want to take it to a transmission shop.

 

[GTPI]

Do you still have the original sensor? If you do, try putting it back just to see if that eliminates the noise. Also check the new one for any unusual contact marks.

 

[Caman96]

What Acdelco part number did you use? C1500 or K1500?
Edit, I just noticed picture, C1500

 

[1998_K1500_Sub]

I wonder if there is a clearance spec between that sensor and the tone wheel on the transmission. Perhaps it’s necessary to shim that sensor to meet the spec. Just guessing.

 

[Va6622]

I’ll try putting the old one back in. At first glance the old and new one look identical but maybe there is a very slight difference. Also I will look for any marks on the new one.

 

[Supercharged111]

Try putting the old and new against one another and see if there's a visible difference in depth.

 

[Va6622]

Finally figured it out. On the sensor, there is a metal piece that is magnetized and collects any tiny bits of metal. That piece was sticking up just enough to hit the gear. I filed it down to be flush with the plastic housing and no more noise.

You must be registered for see images attach

You must be registered for see images attach

 

[Caman96]

Finally figured it out. On the sensor, there is a metal piece that is magnetized and collects any tiny bits of metal. That piece was sticking up just enough to hit the gear. I filed it down to be flush with the plastic housing and no more noise.

You must be registered for see images attach

You must be registered for see images attach

So both replacements had this issue?

 

[Va6622]

Both replacements had the same issue. The off brand as well as the ACDelco.

 

[MNorton]

So glad to find this post! My 94 sierra speed sensor was leaking around the o ring so I got a Dorman replacement and it made a whining noise as described above. I also then ordered a ACDelco sensor but upon inspection I found the same issue the magnetic bars were protruding out past the housing. I filed down the new one and installed and the noise is gone. Thanks for figuring out the issue!