A while back I posted about my cam bearing discovery when I went to upgrade my cam on a magnum 5.9.
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It was a very weird failure, like little worm tracks in the bearings. Due to the winter and no room in garage to pull the motor, I finally got to move outside and pull it this weekend. We put in the new cam bearings, which wasn’t as hard as predicted. Had to redo 2 of them as they were a little off on the oil hole alignment, but all went well and didn’t mess up the new bearings at all.

Took apart the bottom end for inspection and seeing more bearing wear in weird ways. Some look like just worn bearings and some are pitted and some have trash in them. All of the crank journals are fine. Cyl 7 journal has a super faint line, but nothing I can feel with my nail. So it appears the bearings themselves took the hit. Anyone knowledgeable enough to know these failure modes?

This is a ’96 5.9 with 94K miles on it. I change the oil twice a year and use Mobil1 (used Castrol Syntec first few years). Everything ran ok prior, dug into the motor for a burnt exhaust valve on Cyl 1 and decided to do a cam upgrade. The motor is super clean inside and cyl bores are very good. Its just the bearings that are garbage.

Additional photos

Read here great info. Looks like surface fatigue to me.
Doug

https://www.mahle-aftermarket.com/m...114-engine-bearing-failures-brochure.pdf

contaminates

I found that after my post. Looks like I have a combo of a few things. Kinda baffling. Would never have seen this if I did do the cam swap as it ran so well.

Used to see these kinds of failures on new engines from our one engine plant.

When you see one main bearing with the signs shown on your #3 bearing and the remainder look nice, usually means the debris was hiding in the block.
I wouldn’t be surprised the rod bearings you show that are bad are either #3/4 rods and/or 5/6.


Look at then #3 cam bearing too. See if there is debris in it.