Silicone Testing

Silicone Fluid Sampling

To monitor the condition of the silicone fluid during the damper life, sampling plugs are fitted into the damper cover and/or back face of the damper casing so that small samples of fluid (1 cm³) can be extracted from the damper.

The first sample should be taken after 15,000 hours of engine operation or at the first major engine service. After analysing the fluid, AAM will advise subsequent sampling intervals via the analysis report.

Special sampling kits complete with instructions are available from AAM or an appointed service representative

Up to 10 samples of silicone fluid can be extracted from an AAM damper without affecting its performance. It is not necessary to top up the fluid in the damper.

By following this sampling procedure and AAM recommendations, the necessity for overhauling or replacing the damper can be anticipated.

Silicone Fluid Analysis

From the silicone fluid analysis, the internal mechanical condition and operating efficiency of the damper can be established. AAM will recommend the service period for the damper before a further sample of fluid must be taken.

Provided no internal damage has occurred, overhaul is recommended when the fluid has reduced 50% in viscosity value. At this stage, the damping efficiency will be 80%. The average operating time to reach this condition is 25,000 / 30,000 hours, but it can be influenced by engine application and loading as well as non-torsional factors associated with the engine’s environment such as vibrations induced from adjacent machinery, engine mountings, shafting systems and hull vibrations.

If the reduction in fluid viscosity is excessive, or the condition of the fluid indicates internal mechanical damage, AAM will advise the remaining safe service period before overhaul of the damper becomes absolutely necessary.

The AAM laboratory report meets all the requirements of major survey Classification Societies (such as ABS, DNV, BV, KR …) for marine propulsion and auxiliary power installations at the 5 year survey.



Which of these conditions should your sample look like?



New silicone fluid is clear/colourless fluid.



Fluid colourless to light shades of yellow / brown, and free from particles. Usually indicates no internal damage. Fluid viscosity will determine suitability of damper for further service periods.




Requires Service

Fluid dark brown or black in colour, usually with particles in the fluid. As a general rule, dampers with fluid in this condition have suffered internal mechanical damage and have restricted remaining service life.


Emergency Condition

A damper with gelled / solidified fluid is unsuitable for service and it should be removed from service as soon as possible as it is no longer protecting the crankshaft from torsional vibration.