Grinding noise when idling?

To test, push clutch in and see if noise dissapears or lessens.

Then go from there.

 

It's most likely the "throw out bearing" in the clutch assembly. They might of forgotten to lube it a few times during service.

 

I've got a same problem. Grinding/rattle noise when idle at low rpms. However, when the clutch is pushed, the sound seems to disappear. Is it the gears? The grinding noise got worse over a year.. any suggestions? Thanks

 

drop the transmission oil out, open the bottom window of transmission. with the pry bar try to move(slightly ) the gear which is sitting on input shaft. If its loose fix it . also check condition of the reverse parasite gear. Usually that gear is making noise when rolling free. Temporary fix of the rattling noise ? 1 gallon of Lucas into transmission.

 

Funny to come across this thread, my columbia does the same exact thing! It seams to only do it also when the temp out side is mild, when is freezing won't do it and when it hot won't do it. But then the temp is 35F-60F it makes that grinding noise I can't figure it out. I just had my transmission cooling hoses just replaced and new fluid put in, everything looked normal. Truck has 703K on it 18spd with a CAT.

 

Driver I hv a 2013 cascadia just put new trans in on 9-23-20 an I hv same issue when idling. Engine wld sometimes idle for hrs or a few minutes b4 it wld make this awful rattling noise. So what i noticed is my rpm's were going up an down so i knew rt then that my problem was not trans but the fuel quantity control valve. So when engine can't get the fuel it needs an rpms go up too high it throws tranny an engine out of sync just for few seconds. My fuel quantity Control valve is located behind fuel pump. Wld be a good place to start if rpms are fluctuating when idling