Over time the technical team at EXEDY Australia have received reports of repeated CSC (concentric slave cylinder) failures in Holden Cruze models during bleeding of the hydraulic circuit following clutch replacement. Initial investigation with the with the workshop had confirmed the replacement clutch and dual mass flywheel were like for like with the originals so a focus on the overall clutch operating system was undertaken to determine the root cause.
Inspection of the failed slave cylinders had found them to have over-stroked causing fluid to leak from the front of the cylinder body. As the hydraulic circuit under normal condition operates with a 1:1 fluid transfer, the over-stroking of the cylinders indicate an obstruction (blockage) within the hydraulic circuit which was suspected to be the cause.
Further discussions with the workshop had revealed the clutch master cylinder had already been replaced in an effort to eliminate this as a contributing factor to the failure. The circuit had also been flushed several times to rule out contamination, leaving only the hydraulic delivery line and associated fittings as the areas for concern.
After further detailed inspection, EXEDY was able to verify that during removal of the original concentric slave cylinder, a rubber seal/grommet situated on the end of the inlet fitting had dislodged and remained within the bleeder fitting (or elbow as referred to by genuine parts) of the hydraulic delivery line. The vehicle was successfully re-assembled and drove away following removal of this obstruction.
EXEDY explain that while it is possible for fluid to pass into the cylinder during the bleeding process, forced fitment of the replacement concentric slave cylinder (including new grommet) had subsequently created a check valve like situation. In this condition where the fluid could not return back through delivery line, the end result is that the cylinder over fills and leaks because it has exceeded its limit of travel.
Technical bulletin (Note 107) is included in all related EXEDY clutch kits to help inform fitters of this concern.
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