My 7M recently developed a slight knock from the bottom end and I tear the engine apart to look for root cause. The rod bearings at 5 and 6 were worn, interestingly the bearing profile no longer conforms with the radius of the cap nor the rod journal. It has gotten smaller after removal. My question is what would cause the bearing to deform in such a way and is it common ? Here is picture of the bearing and the cap, there is a small gap and the bearing will not sit inside the cap.
There is some shiny surface behind the bearing and on the cap so was the bearing rotating inside the cap ? The journal diameter is still within spec and the clearance was in spec when I put it together a year ago. The other 4 rods have minimal wear and look normal. Should I just replace the bearings or is there other underlying problem that cause the rapid wear ? Appreciate any input.
There is some shiny surface behind the bearing and on the cap so was the bearing rotating inside the cap ? The journal diameter is still within spec and the clearance was in spec when I put it together a year ago. The other 4 rods have minimal wear and look normal. Should I just replace the bearings or is there other underlying problem that cause the rapid wear ? Appreciate any input.
