It is widely understood that the period of time between when the engine begins to turn at startup and the time when fresh oil from the sump reaches moving parts causes the vast majority of the wear an engine sees during its lifetime. A prelube pump puts the oil where it is needed before the engine begins to move, thus reducing this high wear period.
Historically operators of large engines would avoid shutting them down. This was done to reduce startup engine wear in addition to other operational advantages. The largest engines might only be shut down every few months for periodic maintenance. Fuel was inexpensive and environmental concerns were not considered. As the price of fuel climbs ever higher and idle emissions are no longer acceptable, operators are shutting down engines more than ever before.
Fuel costs as well as the EPA and other regulatory agencies are increasingly restricting engine idle time. As a result the number of times some engines need to be started in their lifetime may go up from as few as 80 or 100 to as many as 86,000 times. It’s easy to see how wear rates that were considered acceptable with only 80 lifetime starts would have a significant impact on engine life with 86,000 lifetime starts.
In the end the decision as to whether a prelube system is appropriate for a given installation comes down to the cost benefit analysis of three factors. The number of times the engine will need to be started in its lifetime, and the cost of replacing/rebuilding the engine (including equipment downtime), against the cost of adding the prelube system.
As an example, a good prelube system may run in the range of 3500 euros by the time it is installed. So if the engine is small and only costs 10,000 euros a prelube may be impractical. As the engine size goes up in the calculation though, a 2500 euro investment could save many times its price in future repairs and downtime. Likewise if an engine were only going to be shut down every three months for maintenance, the cost of a prelube system might be unjustified but for a system that is restarted multiple times a day it would be a necessity.
Check out the spreadsheet “Calculate Value of Prelube” www.ese.tc
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