The ceramic clutch washers are on the older SC and SCIC model 4-TEC's. There seems to be more of a "fear factor" on these than there is a real problem. They have had some problems with them, that's why they had changed the design to steel, which really are less efficient than the ceramic.
These washers are the "clutch" washers and allow slip in the charger during radical speed changes to the engine. The chargers rpm is up to 45,000 rpm. With these kind of turbine speeds, is a great amount of friction. Ceramic is 1,000 times more efficient in heat dissapation than steel. But because owner/operators were either switching over to the synthetic 4 stroke oils, they realized they had a problem.
The SC and SCIC models are suppose to use the mineral based XP-S type oils. That oil has been tested with the ceramic washers by the research and development department of Rotax and found to have the correct properities to reduce friction. Synthetic oil has additives that have an adverse effect on the composition of the ceramic clutch washers that in the past, has caused premature failure, so now, Rotax has gone back to the less efficient steel washers so that if an owner/operator uses the synthetic oil, they won't have to worry about the charger blowing up..........:cheers: