Hot Thunking Mercedes E350

Hi Everyone

I have a 2006 Mercedes E350. The car operates normally except in hot weather! Whenever the temps climb beyond 70 degrees, I start hearing a thunking sound in the front of the vehicle as I’m slowing down or stopping. This also occures at slow speeds such as starting from a stop sign and if I turn my steering wheel from side to side. But it only happens in hot weather.



I have taken the car to 4 dealers and they can’t find the problem. They can hear the sound but can’t diagnose it. They have replaced the rack and pinion, the struts and the bushings, but it’s still making the sound. Could it be they replaced a defective rack and pinion with another defective part?



Thanks!

Still thunking in San Francisco.