Rod Bearing Failure Analysis

Did you just hear that the rod bearings in your diesel engine have failed? Are you wondering how exactly that could have happened?

We're taking a look at what might have gone wrong in your diesel engine to cause a rod bearing failure. Keep reading for an in-depth failure analysis.

Has a diesel engine failure left you in the lurch? Our ASE Certified Technicians are ready to help you get the replacement parts your need for your repair!

Give Us A Call!


Want more information on your rods and rod bearings? Be sure to read our connecting rod failure analysis!


Bearing Failure Caused by Foreign Material on the Back of the Bearing

One of the main causes of rod bearing failure is the presence of foreign material on the bearing itself.

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).

Rod Bearing Failure foreign material | Highway & Heavy Parts
Rod Bearing Failure tape pattern | Highway & Heavy Parts

Bearing Failure Caused by Excessive Wear in Support Components

Additionally, your rod bearing failure can be caused by excessive wear in the support components. The pattern on the rod bearings indicate either a barrel shaped crankshaft or distorted and worn connecting rod bores.
Rod Bearing Failure support component wear | Highway & Heavy Parts

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.
Rod Bearing Failure Gouges in Bearings | Highway & Heavy Parts

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. 

Cylinder Kit Failure from Lack of Proper Lubrication

Another possible cause of failure is a lack of lubrication in your diesel engine. The pictures below show what this can look like. 
Poor lubrication can also affect your main bearings. Learn more in our diesel engine main bearing failure analysis.
The first two pictures show the spun connecting rod bearings.
Rod Bearing Failure Improper Lubrication | Highway & Heavy Parts
Rod Bearing Failure Lack of Lubrication | Highway & Heavy Parts
The next picture shows the lower part of the connecting rod that holds the rod bearing. Note that the rod is not drilled for an oil feed hole to the piston pin.
Rod Bearing Failure connecting rod | Highway & Heavy Parts
The next picture shows the failed piston and connecting rod. The piston skirt and liner were reduced to pieces.
Rod Bearing Failure failed piston and connecting rod | Highway & Heavy Parts
The final picture shows the remains of the piston cooler.
Rod Bearing Failure failed piston cooler | Highway & Heavy Parts
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 updated during the overhaul to the recommended drilled rod. The rod bearing failure was caused by lack of proper lubrication. 

Are you in need of diesel engine replacement parts?  Our ASE Certified Technicians can help you get the right parts for your repair job. Call them at 844-304-7688, or request a quote online!

Originally Posted November 18, 2015; Edited March 30, 2020