My Nissan NV3500 van vibrates/shudders while stopped and in gear. The vibration goes away if I shift into neutral, and also goes away as soon as I begin accelerating from a stop. I just (2 days ago) swapped the engine with a new long block for unrelated reasons, and inspected the motor mounts at that time. The shaking predates the motor swap, as it was first noticeable a few weeks ago. I don’t know a lot about automatic transmissions, but the effect reminds me of what would happen if you let the clutch drag a bit at a stop with a manual transmission. What other tests can I perform to narrow this down? Is this any kind of classic symptom? I imagine a torque converter that is sticking, though I don’t even know if that’s a thing.
It’s not a thing. This will be tough to nail down considering all the recent work. My first thought is engine mounts, but you say you inspected them. Does this thing have fluid filled mounts or solid?
Just two solid rubber mounts.