luxcar

I have 2008 GL550 with 179K on it. Transmission jerks when you put it in reverese when cold. I can feel the shift from reverse to Drive. For about a month it has rumble strip kind of noise from rear. My indy was not able to diagnose the problem. Now I can feel shudder when I try to accelerate hard and it downshifts when going around 50mph. They are no warnings or lights. Should I
1. Take it to dealer for diagnosis
2. Take it to a local MB specialist (Burdi Motorworks in Chicagoland)

Background
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Car was running flawlessly until indy mechanic changed the radiator. He did not attach the transmission line. I noticed fluid under the car and took it back. He attached the transmission line. I have to take it to dealer to top up transmission fluid. It was about 1.25 quarts low. Dealer said it should not cause problem as I did not drive much on low fluid. The car was shifting hard from 1 to 2 but was getting better as I drove.
Few days later I got overheat message because the radiator hose disconnected and all fluid leaked. I stopped quickly in about 100 meters and had it towed to mechanic. Mechanic cleared CEL light, reattached the hose and put new coolant (OEM). Since then the rumble strip kind of noise started from rear and now it is shuddering.

Plutoe

If Burdi has a Star system aka XDOS take it to him and take your mechanic off you holiday gift card list, didn't reconnect the transmission coolant lines---wada joke.

luxcar

Burdi Motorworks does have Star system. They could not find any fault codes. They stated that transmission fluid smell like burnt and is dark in color. They are advising to replace transmission based on condition on transmission fluid. They also stated that the chain in transfer case is loose.

Two months ago I have dealer top up the fluid after it leaked (hose not attached properly). I asked them to check the condition of the fluid once they drain it and they said it is ok. So my guess is that overheat caused by disconnected radiator hose may have resulted in transmission overheating and fluid deteriorating. Should I go to dealer for second opinion?

luxcar

Update: Took it to dealer for diagnostic. They suggested to do a transmission flush as fluid probably got burned due to empty radiator and overheating. Had the transmission fluid flush and it is driving normal again. No more jerk, hard shifts or rumble strip noise