If there is a reason you are changing the oil pump (pump failure/extremely low pressure, etc.) then I would at least pull a rod cap to check for damage to the bearing. If not, and you have under 100K on the engine, no need to change the bearings.

Over 100K I WOULD do at least the rod bearings. The mains are tougher to get at to change with the engine still in, and they typically last 250-350K anyway.

If you pulled the head, you might as well deglaze the cylinder walls and renew the rings when you do the rod bearings if you have over 150K on the engine. Usually you have NO ridge on these blocks and the original cross hone marks are still visible, so STD rings work perfectly (mike one cylinder or piston to be sure that it wasn't previously rebored, of course).

Bob

Hey all,

I am going to be installing a new oil pump on a 87 635csi and wanted to know if it is necessary to change the rod and main bearing while i am at it???

Can i just change the pump and leave the original bearings??

thanks