My Honda Accord’s automatic transmission makes a single “clunk” sound when backing up, almost immediately after shifting into reverse. This occurs intermittenly, but usually first thing in the morning. It sometimes occurs when shifting into drive, again usualy first thing in the morning. The car is a six cylinder with 60,000 miles. What is the cause and what should I do? Note: The transmission also seems to down shift more often than one might expect on the highway, when going up a modest grade, but only when it is in D4.
I suspect the motor mounts. I had a Dodge do this. I was sure it was the transmission, but it was not, motor mounts let the engine rock when shifting direction and clunked nice and loud.