Rod Bearings Failure Analysis

A. Bearing failure caused by foreign material on the back of the bearing

The next two pictures show a rod bearing with a piece of tape or paper on the back of the bearing where it seats in the connecting rod (blue arrow); the pattern of the tape is clearly visible on the front side of the bearing where it came in contact with the crankshaft connecting rod journal (green arrow).

The final picture shows the uneven wear patterns on the rod bearings. Gouges in the bearings are caused from abrasive contamination not properly removed from the engine during overhaul.

Conclusion: The bearings have uneven wear spots most likely caused by either a worn crankshaft or out of round connecting rod bearing bores. One bearing had a piece of tape on it that was between the bearing and the rod bearing surface. The pattern of the tape was clearly visible on the reverse side of the bearing. 


B. Bearing failure caused by excessive wear in support components

The pattern on the rod bearings indicate either a barrel shaped crankshaft or distorted and worn connecting rod bores.
C. Bearing failure due to worn crankshaft or out of round connecting rods

The final picture shows the uneven wear patterns on the rod bearings. Gouges in the bearings are caused from abrasive contamination not properly removed from the engine during overhaul.
Conclusion: The bearings have uneven wear spots most likely caused by either a worn crankshaft or out of round connecting rod bearing bores. One bearing had a piece of tape on it that was between the bearing and the rod bearing surface. The pattern of the tape was clearly visible on the reverse side of the bearing. 


D. Cylinder kit failure from lack of proper lubrication

The first two pictures show the spun connecting rod bearings.
The next picture shows the lower part of the connecting rod that holds the rod bearing. Note; the rod is not drilled for an oil feed hole to the piston pin.


The next picture shows the failed piston and connecting rod. The piston skirt and liner were reduced to pieces.
The final picture shows the remains of the piston cooler.
Conclusion: The above pictures show two areas of failure, the connecting rod bearing and the cylinder kit. Also shown is a damaged piston cooler. The piston cooler if bent can cause a piston to seize and cause the piston pin bearing to fail. The connecting rod was not up dated at time of overhaul to the recommended drilled rod. The rod bearing failure caused by lack of proper lubrication. 

  • Posted on   11/18/15 at 01:48:52 PM   by Sara  | 
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