The brief
The GLA180 had picked up increased vibrations, the engine visibly moving more than it should under load and gear changes, louder engine noise inside the cabin, and clunks from the bay, with cracked, torn rubber visible on the mounts. Those are the signs of worn engine and gearbox mountings. The engine and gearbox sit on rubber mounts that take their weight and soak up the shake. As the rubber ages it sags, cracks and tears, and once it does the drivetrain can move around more than it's meant to. That extra movement is the vibration coming through, the clunk as it rocks on a gear change, and the harsher, louder engine note as the shake transmits straight into the body. Mounts that have worn together produce exactly that, and they only get worse, risking other components as the drivetrain shifts around.
The diagnosis
On the lift each mount got a pry-test. The engine mount and the gearbox mount had sunk visibly with cracked, torn rubber. All of the drivetrain mounts were tired at the same time. When they go together like that, you do them as a set. Replacing one fresh mount next to a sagging one just loads the new one harder and you're back in soon, so the call was the full set.
The work
The engine and gearbox were taken onto transmission jacks to take their weight, and each tired mount came off in turn. New genuine Mercedes-spec mounts went in across the set, every fastener torqued to the manual figures. With everything bolted up, the drivetrain was checked to be sitting square in the bay before the engine was let down to load onto the fresh mounts. A road test confirmed the shake, the clunk and the harshness were all gone.
The outcome
Smooth at idle, no clunk on shifts, no excessive engine movement, no vibration through the cabin, and the engine note back to normal. The GLA180 went home with the drivetrain held properly again. Engine mounts wear as a set and they take the rest of the drivetrain's refinement down with them, so doing the whole set together resets the lot rather than chasing the next sagging one a few months later.
