97 tahoe, grinding noise

[nhbluevip]

95wintt, No I don't believe so. It was a complete swap. There was a rebuilt transmission in a 97 extended cab truck. They took the tranny and t-case out of that and put it mine. I may be miss understanding something, but is the torque converter part of the tranny?

 

[95TwinTT]

They often do change the TC with the tranny, but not always. I bring it up because at highway speed, the speed differential between the stator and turbin are close enough to have lower frequency sounds that may sound like grinding. As soon as you go into neutral, the differential goes way up again and may be out of audible range. You are also in TC lockup at those speeds.

Just a long shot, but it would be easily tested to see if any change between running in 3rd or 4th gear for a couple of tests. If the same, not much time wasted testing.........

 

[nhbluevip]

THANKS! I am at work until 2. I will try it on the way home, and see. The more I read, this may be the torque converter. It also at around 80MPH, if you barly press the gas, sometimes there is a quick skip, almost like a missfire. However ive noticed anything over 75 MPH, if you let off the gas, everything appears to be fine.

 

[nhbluevip]

So while driving home on the interstate, I let off the gas and it began its usual grinding between 70 and 60 mph. I put it into 3rd and it went away. Does this mean the torque converter?

 

[SunlitComet]

Here is a manual on the 4l60e tranny if you want to learn more about the tranny or converter operation. It is a lot of read.

http://www.sunlitcomet.com/pdf/auto/4l60e.pdf

 

[95TwinTT]

So while driving home on the interstate, I let off the gas and it began its usual grinding between 70 and 60 mph. I put it into 3rd and it went away. Does this mean the torque converter?

When driving in 3rd gear, and the Torque Converter is in lockup, the engine speed is the same as the tranny and driveshaft. When in 4th, the engine is turning slower than the driveshaft.

If the difference in those speeds is causing a noise, I would have to guess that it most likely is in the Torque Converter or Transmission.

I would go to a transmission shop and have a technician go for a ride and get their opinion before taking anything apart. They might recognize the particular noise.

If the Torque Converter is the same one you had with the old trans, I would suspect it is related to the problem. Somtimes flex plates can crack and contribute to the problems as well.

 

[nhbluevip]

Well I found out that the torque converter was changed with the transmission. I think Im going to take the front drive shaft out, and drive it, and see if the grinding noise, vibration goes away, that way I can see if it is something in the front end, vibrating down the shaft.

 

[arowsom]

I've found that you can rule the hub bearing in or out if the noise goes away when you turn left or right.