Noise in transmission


Retired member
In the morning when the car is cold and I shift into reverse, transmission makes a metallic crunch type of noise...also, on highway, temp was 200 and it seemed to be a couple hundred rpm higher than usual. If I shifted from overdrive into drive, rpm's went up. So overdrive must be working. Any ideas where to start looking? Of course the noise went away when i took it to mechanic, but it only seems to happen when the car is cold. Thanks.