I hate to admit it, but I think I may have a problem. I experienced a thunking sound and jerky shift when quickly changing direction. I was making a quick turn around on a narrow street once and another time in a gas station to move to pump that worked. Since I was shifting rather quickly, I may have induced the sound by shifting prematurely and not having my foot solidly on the brake.
I have had absolutely no problems with the transmission before, so I think it might have been my fault. The transmission works perfectly well under all other driving conditions.

However, I would like to know if anyone else has experienced this or is this my “warning shot” that something is about to happen? I have a 2003 RX300 with 122,000 miles on it. I have been browsing my local dealer’s rotating stock of certified RX 350’s for a few months, but now I might have to get serious.

Dr Dan

PS FYI
My repair log for those 122,000 miles:
I resurfaced the front rotors twice. The original rear pads are still good.
Repaired 3 of the four door lock opening motors,
Replaced the hatch lifting gas cylinders
Replaced the air bag computer only $$ expense
Normal timing belt service.
Still have the ongoing Gerbil noises behind my glove box. ????
Of the 18,000+ views of my air servo removal procedure, only one person commented that the procedure actually fixed the problem.

I still get 19 to 21 MPG under all driving conditions.
It is the most reliable and comfortable vehicle I ever owned, even better than my old 1984 MB 300SD with 235,000 miles on it when I sold it.

 

When mine went out, it started making a high pitched noise when shifting from 1st to 2nd. It was like a whiny kazoo sound or something. I didn't allow it to fail, I took it to the dealership and had them diagnose it and of course it was bad. I had an aftermarket warranty that took care of it thankfully.

Too bad about the 1st gens having that problem, other than that they are solid vehicles.

 

I took the RX to a reputable shop. We drove the car around and repeated the failing circumstances. A thorough analysis of the conditions when the thunk occurred revealed that it was not the transmission, but the motor mounts. The thunk was just coincidental to the time of the shift. With the front end of the car angled downward on a driveway and then shifting into reverse to go back uphill is when the thunk happened. It was suggested that I not use after market mounts because they do not hold up as well as the Lexus/Toyota OEM.

Dr Dan

 

Richard Gere said to search for "Air Mix Servo" on this forum. Easy solution.