Quote:
Originally Posted by Ajolives
It’s also important to note that Mahle did not specifically state all bearing failure causes are due to corrosion. This brochure was specifically targeted at the corrosion piece. I’m no engineer, switched to finance as one does, but I would think oil degradation/contamination is certainly a leading cause.
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It wasn't specifically target at corrosion. The document originated as I called in a favour for a Race Unit engineer to take a look at a set of bearings supplied by a user on another forum (he's also active here) hoping to get some clarity on the "issues" from an engineering point of view.
I raised questions on a call with him on the unusual wear pattern, specifically in the parting line on the bearing where the largest clearance is due to counterboring missing the overlay. This in itself put a very big question mark on clearance being the issue. I initially suspected excessive crush had caused the bearing to distort, but on examination this was not the case. The explanation on the parting line missing overlay starts to go above my head. The basic explanation is the way the overlay is plated there are greater concentrations of lead in this area. As it is the lead that is attacked, this area can show more corrosion.
It transpired that other bearings have been examined and are in the MAHLE database with the same issue. All have shown overlay corrosion. Now I'm sure there are bearings out there that have failed for other reasons, they are not covered here as they have not seen samples.