I notice while accelerating hard and the car is going from first gear to the next, at that moment I'll hear a tapping sound from the engine, maybe lasting a second or two, right at the height of the gear change. There's nothing while accelerating normally. When it happens it's feint and I doubt anyone would notice it if they were riding in the car. It goes away when the gear change is complete. Otherwise the engine is operating as normal and actually sounds quite good. It's going on 160,000 miles on the odo, and it's otherwise in great shape. Any suggestions?

 

wondering if it could be pinging (aka engine knock). what grade gas do you typically run? a quick experiment would be to fill with a tank of premium (ie 93 octane or the most expensive grade ) to see if that changes anything. Does it happen only under full throttle or high RPMs?

 

Happens only when changing from first to second gear (automatic). I took it to a trusted, local Volvo repair center and they diagnosed it as a bad connecting rod bearing. Said it would cost about $1000 to replace.