Hi Dave,

My 1999 V70 XC had a similar problem but it was easily determined to be the transmission shifting between 3rd and 4th gears. The bump occurred more harshly when it was hot out. That is the hotter it was out side the harsher the shift/bump.

However, if I understand you correctly your so-called bump occurs independently of transmission shift. You can easily determine this by watching the tachometer. If the bump occurs with a drop in engine RPM then it is the transmission that is causing the bump feeling.

If I am correct and your bump occurs independently of transmission shift then I would bet that you have a problem with the drive train mounting points. That is either an engine mount is broken or loose or the sub frame is not mount correctly. Have the dealer check all the engine mounts (I believe there are 4 mounts, 1 top and 3 bottom). The sub frame on my car was not installed correctly at the factory. The dealer gave me the usual “We can not find anything wrong” answer. So I took my car to an independent Volvo repair shop and they found the sub frame spacers were worn causing the sub frame to move around. Also a bad ball joint could cause a popping sound if it too were bad.

Good Luck,

Steven---