HARNESS AS-REAR CHASSIS 1155606 - Caterpillar

Introduction
Note: Caterpillar recommends S O S Services for monitoring the condition of the fluid systems in your equipment. S O S Services enhance a variety of Caterpillar Preventive Maintenance Programs.This article explains the reasons for elevated copper levels that are sometimes observed in used oil samples. These elevated copper levels can be dramatic. Customers that observe these elevated copper levels are very concerned about excessive wear or component failure. In most cases, the customer should not be concerned about these elevated copper levels: the condition does not usually indicate excessive wear and/or component failure. However, it is important to understand the cause of the condition.Affected Compartments
The elevated copper levels that are described in this article occur in compartments with a lubrication system that has an oil cooler with copper tubes.On Cat Machines, the following compartments typically have an oil cooler with a copper core:
Engine
Power shift transmission
Hydraulic system
Steering systemOn most machines, the lubricants for these other compartments are not usually cooled: front wheels, tandem drives, differentials and final drives. Consult your Caterpillar dealer about the oil cooling systems for your machine.Oil Cooler Break-In
Note: S O S Services oil analysis measures the levels of several elements in used oil samples: copper, iron, chrome, lead, aluminum and silicon. Many of the S O S Services labs also analyze the used oil for sodium and for potassium in order to check for contamination of the oil by coolant.Elevated copper levels are usually associated with the break-in of a new oil cooler. The copper level in the used oil may have a dramatic increase. However, the other wear elements in the used oil remain at normal levels. S O S Services analysts are familiar with normal levels of wear elements in used oils and the analysts are trained to identify this condition of elevated copper levels.When this break-in of the oil cooler occurs, the copper level can reach several hundred parts per million (ppm). In some cases, the copper level can exceed 1000 ppm. Usually, the copper levels diminish within two or three oil changes.Illustration 1 represents the typical trend of copper levels. The graph demonstrates some results from analyses that were performed during the development of a project. The engine oil was analyzed at every 50 service hours and the engine oil was changed at every 250 service hours.
Illustration 1 g00955365
The engine oil samples that were obtained during the initial 250 service hours revealed an increasing copper level that exceeded 200 ppm. Between the first oil change and the second oil change, the copper level rose to less than 50 ppm. By the third oil change, the copper level was normal.Causes of Elevated Copper Levels
Elevated copper levels occur when copper dissolves from the surface of the oil cooler tubes. The copper is in a solution with the oil and an insignificant amount of copper is removed from the oil cooler's tubes.After a period of time, a protective coating forms on the copper tubes and the reaction stops. The equipment will not be damaged