It seems bearing failures in MINIs are occurring at an increasing rate. I’ve been involved in a support role for more than a few engine rebuilds recently, which could account for my increased awareness level. When my motor began shuddering on start up around the 100k-mile mark, the knowledge it’s likely the result of increased tolerances and not a death knell, didn’t/doesn’t make me feel any less queasy. When it chirped & squeaked one morning I knew it was time to take a closer look, sure enough, evidence of inadequate oil distribution could be seen topside. The most likely culprit would have to be the oil pump. The gerotors looked ok and the pump body wasn’t wallowed out, but the outlet gasket was smushed. Below are photos of the outlet gaskets from a 20k-mile pump on the left, and my 110k-mile pump on the right. An irregular surface could be felt on the deformed gasket so I assume the seal was not occlusive, this would allow pressure to bleed off at the source. I noticed the oil pressure control spring had taken a set a couple mm short of a low mileage spring from a cannibalized Cooper pump, and there was a machining difference in the spacer bushing between the two builds. I doubt the difference could cause problems, just observations to share. What could cause pressure loss here was the flat, stiff, aged O-ring. In each photo below, the newer low mileage parts are on the left, early model high mileage parts on the right. To be on the safe side, a low mileage pump freshened up with new O-ring and gaskets replaced the high mileage pump. At this point the chirping squeek has gone, so I'll call replacing the old oil pump successful maintenance.
Good to get this information out here. BTW when I click the thumbnails, I get a window that displays the thumbnail again, not a larger image. Nathan? Any idea why?
Awesome information! Thank you for sharing; it'll be very helpful to many MINIacs in the future [if not already].
Interesting. I'm going to buy a new pump for my R50. I heard the R53 pump fits but is higher volume. Is this true?
My oil seals were like yours! I bought the 2 oil pump gears and a new spring and valve to be sure the oil pump is back to new. There was no wear in the housing.