Even with as much emphasis as we place on proper monitoring and maintenance of the lubricant in the equipment, we often forget that the coolant exists. Yet coolant condition monitoring and replacement is just as critical to prevent crevice corrosion in cooling systems, and improve reliability. When replacing water based coolants, always dilute using only distilled or deionized water - never tap water. The chloride content in tap water in many locations is quite corrosive, and will greatly increase corrosion rates in cooling systems. (Daryl Beatty, Technical Service & Development, Dow Chemical)

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Anybody who has been in the lubrication field for at least a couple of years has likely been badgered by problems relating to air contamination. Indeed, aeration and foam present many serious reliability concerns which merit immediate attention by machinery maintainers. However, for most people, the causes are too complex to troubleshoot, leaving the root-cause mystery unsolved. Sometimes an oil change provides a suitable remedy, but too often it serves as only a temporary fix. In other words, there is a need to find why it happened.

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Question: In diesel engines and other outdoor machines, wear metals such as iron, usually correlate to what common element found in dirt?

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"We have a right angle gearbox that is splash lubricated in our plant. I have read that the oil level should cover the lower gear teeth but the oil sight glass seems to want an oil level that is about an inch above the requirement for the gears. Should I drop the oil level down to the proper level for the gears to reduce the chance of oil foaming and air entrainment?"

You are correct. The oil level should cover the lower gear teeth and thus submerge the gear tooth contact area. But I would be reluctant to drop the oil level from what the OEM has indicated by the placement of the sight glass. Perhaps there was an error in the height placement of the sight glass, but I suspect that there is a bearing that requires that higher oil level, or the oil level indicated is needed for start-up and may drop once the unit is running. Dropping the oil level could starve a bearing within that gearbox of oil. I would only drop the oil level after consulting with the gearbox manufacturer and verifying that the sight glass was located in the wrong position.

Bob Scott, Noria Corporation

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