Today I was cruising at (very approximately) 65 mph and 3500 rpm in top gear in my 1991 300SE. I decided to stomp on the accelerator, and the transmission downshifted and the rpm went up to 5000 or more, good. Zoom, off we went, fast — but I kept the pedal on the floor and then the transmission downshifted again … NOT good.
I saw the rpm needle swing high, way deep into the red-line; if not to 7000 rpm then darn close to it. The engine was surging too; presumably trying to limit the engine speed by doing so.
I backed off and drove normally, listening for obvious sounds of engine damage. It all sounded normal.
After a while, I tried the downshift again, but this time I used the shift lever. Starting today, that has become my preferred way of downshifting.
I’m worried about engine damage. I plan to do a compression test soon, to check.