Sealing System Leakage Analysis - Others


Check Bolt Holes for Leakage

Probable Causes Actions or Countermeasures
Threads in housing tapped into fluid reservoir. Review product machining specifications.
Insufficient bolt tightening. Review specifications for bolt torque.
Undersize bolt diameter or oversize thread tap diameter. Measure bolt and bolt hole for fit.
Material thermal expansion incompatibility. Insure the bolt and housing material have similar thermal characteristics for temperature extremes.
Vibration. Employ locking method to insure bolt does not work lose.
Bolt fracture. Check bolt loading specifications and operation parameters.
Contamination. Insure bolt hole is free of particles or corrosive fluids prior to bolt installation.


Insure bolt housing and bolt material are compatible with application environment.
Bolt missing. Install specified bolt.
Cross threading. Re-tap and use correct bolt.
Improper bolt. Change to correct bolt size.
Improper head type Change to correct bolt.

Check Gaskets for Leakage

Probable Causes Actions or Countermeasures
Heat aging causing stress cracking or compression set. Use high temperature gasket material.
Improper machining of mating surfaces. Review machining procedure for proper machining techniques.
Casting porosity or other hardware surface defects. Inspect hardware surface for visual defects prior to gasket installation.
Excessive pre-load of gasket resulting in gasket compression set. Review bolt torque requirements.
Gasket swelling, softening, or hardening due to chemical attack. Check fluid compatibility of gasket material.
Torn gasket. Use proper installation procedures and tools.
Crimped or folded gasket. Use proper installation procedures and tools.
Gasket blow out. Review system pressure specifications and field application conditions. Check hardness of gasket.
Dry gasket. Replace gasket.
Wrong size. Use correct gasket.
No sealant on gasket. Apply sealant.
No gasket Install gasket.


Check for Axial Shaft End Play

Probable Causes Actions or Countermeasures
Worn thrust bearing. Replace bearing, check bearing load specification, and gap tolerances.
Shearing of lock ring or locking key. Check hardness of lock device and dynamic load on shaft.
Wear sleeve on shaft is loose. Check press on bond fit for sleeve.
Negative stack-up in hardware tolerances. Review product drawings.


Check for Excessive Shaft Run-out

Probable Causes Actions or Countermeasures
Failed bearing. Exceeded bearing load capacity. Excessive wear or contamination-replace bearing.
Excessive shaft deflection. Balance shaft and/or support shaft better.
Shaft machined out of tolerance. Review shaft drawing specifications and production limits and tolerances, and adjust process.


Check for Shaft-to-Bore Misalignment

Probable Causes Actions or Countermeasures
Poor initial alignment Review design and assembly operations and provide accurate alignment.
Seal manufactured with high radial wall variation Review production quality data and adjust process.



Obtain Oil or Sealed Lubricant Sample

Probable Causes Actions or Countermeasures
Wrong fluid. Correct procedures for initial fill or specify service fill.
Degraded fluid. Review fluid specification verses sump temperature and change the fluid requirement or sump temperature.
Degraded pre-lube. Specify pre-lube with temperature capabilities equal to or better than fluid sealed.
Contaminated fluid. Locate source of contamination and remove.



If Wear Sleeve is used, Check for Leakage Between Shaft and Sleeve

Probable Causes Actions or Countermeasures
Improper sleeve press fit. Inspect at removal.
Damaged shaft. Inspect at removal.
Improperly finished shaft (chatter). Inspect at removal.


If Assembled Seal, Check for Leakage Between Clamped Elements

Probable Causes Actions or Countermeasures
Improper seal manufacturing (insufficient clamping force). Consult seal manufacturer.
Severe dish or bulge of seal assembly at time of installation Excessive interference between seal OD and bore.


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February 23rd
Here is a great article on grease compatibility . . .
The Skinny on Grease Compatibility

July 30th
 Here is a link to a great article about how to avoid particulate contamination . . . Obviously it goes without saying that a sealing...
How to Avoid Particulate Contamination