76139 Mercury SPRING, INTERLOCK ACTUATOR SCREW

Introduction
This Special Instruction provides guidance for when levels of lead (Pb) in engine oil samples are elevated to a point of Action Required according to S O S wear tables.Lead in engine oil does not always come from main or rod bearings. However this Special Instruction presumes that the bearings are the most likely source. Lead from other sources, such as excessive thrust washer or bronze bushing wear, most commonly is accompanied by highly elevated levels of copper (Cu).Note: This publication is to be used to explore the root cause of elevated lead in oil samples. Due to the risk of debris introduction from physical bearing inspections or replacements, investigate the root cause thoroughly prior to disassembling the engine.Additional Resources
Professional classroom instruction on oil sampling, analysis, and interpretation is available, course 08E1017 S O S Services Interpretation Training I. Course information, help sheets, wear tables, and community discussion is available under S O S Services on the Knowledge Network (https://kn.cat.com). Other helpful resources:
Operation and Maintenance Manual, SEBU6250, "Caterpillar Machine Fluids Recommendations"
Special Instruction, SEBD0640, "Oil and Your Engine"Action Required : Example
Illustration 1 g03403230
Typical example wear table. Values subject to change.
Illustration 2 g03403233
Example of a trend chart with lead level elevated to Action Required
If an oil analysis returns from the lab with an elevated level of lead and action is required, follow the steps listed below.
Review and Validate the Sample
Determine the Root Cause - Wear or Chemistry
Resolve and ProceedReview and Validate the Sample
Illustration 3 g03403239Sample Collection, Age, and AnalysisVerify that the sample was collected and delivered correctly. Verify that the lab has been used in the past. Verify the hours of the oil. Was an oil change missed?Compare to TrendHas the lead level in the oil from this engine been steady or trending upward in recent samples? If the lead level is trending up, has the rate of increase been gradual or rapid? Has a follow-up sample been taken and analyzed to confirm a rapidly increasing trend? If the trend is indeed increasing rapidly, the engine should be shut down and action taken immediately to investigate and resolve the problem.Service RecordsCarefully consider service records including recent component changes, modifications to lubrication, cooling or fuel systems, or any adjustments to the oil renewal system if equipped. Do service records reflect any change of suppliers or formulations of oil, coolant, or fuel? Lead is common in various greases sometimes used as assembly aids.Operation RecordsConsider operational changes including major changes in haul cycle, profile, shift, operator, and so on. Is the operator noting anything unusual? Has the fuel burn rate changed or have there been any changes to the rate of oil consumption or frequency/volume of oil additions?Consider Collecting Another SampleHas resampling been considered after changing oil and filters? Has this sample been collected early due to elevated lead in the previous sample?
Table 1
Review and Validation Checklist
Points to Consider Notes
Sample Collection, Age, Analysis Correctly Collected?
Correctly Analyzed?
Reported Hours Correct?
Oil Change Intervals (OCI) Correct?
Compare to Trend from this engine Steady?
Gradually Increasing?
Rapidly Increasing? (1)
Service Records Major Component Replacements?
Modifications to lubrication, cooling, or fuel system?
Changes in Oil, Coolant, of Fuel Suppliers?
Changes in Oil, Coolant, or Fuel Formulations?
Operation Records Changes to haul cycle or profile?
Changes in shift or operator?
Noteworthy operator comments?
Rate changes in fuel burn or oil additions?
Consider Resample Is it safe to change oil and filters and resample?
Has the engine been resampled?
(1) Shutdown and resolve, if rapidly increasing trend is confirmed.Determine Root Cause
Lead is most often removed from bearings by mechanical wear or chemical wear.Mechanical Wear
Mechanical wear of main and connecting rod bearings most commonly originates from one or more of the sources listed below:
Dirt/Debris Introduction from Service or Operation
Dirt Ingestion Through the Air System
Abnormal Operating Conditions
Out of Specification or Damaged ComponentsDirt/Debris Introduction from Service or Operation
Illustration 4 g03403290Dirt and debris can be introduced into the lubrication system anytime the engine is opened for service, repair, or oil additions. Review service and operation records to understand when the engine has been opened and to identify other possible sources for dirt or debris entry, including changes in personnel. Routine inspection of oil filter media and magnetic drain plugs for signs of debris is encouraged.Note: The first few samples from new or newly rebuilt engines often contain elevated levels of silicon from seal materials. Elevated levels of silicon in new or newly rebuilt engines can be normal.Dirt Ingestion Through the Air System
The chemical makeup of dirt is regionally unique, but generally dirt contains at least silicon and aluminum in a ratio close to Si:Al = 3:1. Dirt ingestion through the air system often generates elevated levels of iron and chromium first from liners, pistons and rings via abrasive wear. Levels of lead often rise shortly thereafte