LexRexBlue

I brought my RX 300 to the dealer because of a strange sound. It occurs when the car is driven at 40mph and you let the car coast (no acceleration and no braking). It hums. They said it was very rare and it is the differential in the transmission, but it was covered in the warranty as part of the drive train. Has anyone else had this problem?

ryca9799

Mine had the same problem but it was coming from the AC. Turn off the AC and see if the problem goes away. If it does, there is a TSB to fix one of the AC lines. It occurs when the RPMs are between 1100-1400. I would hear it at exactly 40 MPH when letting off on the gas and also when accelerating from a stop. You can also try to duplicate the sound by putting the car in neutral and gently rev the engine to the above RPMs and see if you hear the sound.

LexRexBlue

Thanks for your theory. I'll try it. Meanwhile the part from the transmission has come in and the dealer is supposed to change it on Tuesday.

ryca9799

What was the result of your service appointment? Did the part correct the problem or was it the air conditioning hose?

LexRexBlue

I tried the air conditioning trick to no avail. The sound actually started to get worse occuring at 35 mph, too. Then I brought the car in yesterday. They changed the parts and the car seems "zippier" and the noise has stopped for now. However, it has gone before without the noise for a couple of days! I am going out of town for a few days and time will tell. I'll keep you posted. It is related to the transmission and covered under the warranty.