hello dieselers,
On my 87 300dt, I just changed out the vacuum pump that had the fatal ball bearing issue. Examining the cam surface indicated that there was a noticable groove worn on one side approx at the 5 O'clock position. Is this something to be concerned about?
Dan
'87 300dt 135K

YES! This is something to be very concerned about. If that surface is not perfectly smooth you will have a repeat failure in no time flat. Your I/P timer assembly will have to be replaced along with the vacuum pump. Timing chain and tensioner should be inspected closely and replaced as well if needed.

Thanks Duxthe1,
(I think). The strange thing is that the orginal vac pump showed no signs of wear on the bearing surface. And it also did not have the dam gasket which may prevent wear by immersing the cam in oil each rev. I did install the dam gasket.

Dan