Vibration analysis of reciprocating gasoline engines has proved to be very successful in solving vibration-related engine failures at an engine production facility. The “pull ratio” of engines returned to the factory has been reduced by 70% over the pre-vibration testing levels.

Problem Statement 

At the end of the production line of 4-cylinder gasoline engines are six test cells where the completed engines are rigged up and started-up for the first time after manufacture.  Historically, the engines were allowed to warm up for a few minutes and then inspected manually by the operator.  The operator would listen for unusual noises and check for oil or water leaks using an ultraviolet lamp. The next step in the evolution of the test cells was to use a portable data collector to acquire vibration data from several points on the engine block while the engine was running.  From 5 to 10 analysis parameters were defined to aid in diagnosis of internal problems in the engines.  Alarm limits were assigned to the parameters to provide a pass-fail result for the test.  After successful demonstration of the addition of vibration analysis to the engine test cell program, the manufacturer asked MAARS to design an automated system to replace the manual vibration data collection process.

Vibration Analysis

Gear damage was one item that was easily identifiable for pulling engines prematurely. One can see from the photograph and data shown below that this defect is easily identifiable through spectral analysis. Gear damage and a close-up are shown below:   

Test Program Results

The use of vibration analysis has proven to be an invaluable tool in the production line testing of engines. The reduction in pull rate, coupled with the identification of specific engine faults, enables the facility to enjoy a significantly improved reputation for customer satisfaction. The MAARS Model 4010 Engine Test Stand Monitoring System provides a cost-effective solution for engine testing with a significant impact on engine production quality. In addition, production line speed was increased over the manual method of data collection using a portable data collector.