CAUTION ON THE USE OF SILICONE BKAKE FLUID IN ESAMATIC BRAKE SYSTEMS

Posted by Peter Packard On 2007/9/18 6:48:41

Hi all, Two posts in the one day, I must be hooked! Please be cautious in changing to silicone brake fluid (SBF)in the Esamatic brake system. I USED to convert all of my hydraulic brake cars to SBF, almost entirely because it was lubricatng to the seals and did not attract/absorb water. (currently have 4 packards on SBF)
I recently had an experience whereby about 6 months after I converted my 56 Patrician to SBF, the brakes started to not release, to the extent that on at least 3 occasions they locked the brakes up completely. My diagnosis was swelling of the main seal covering the compensator port, not allowing fluid to release back to the master cylinder reservoir. It would appear that the nominal 7% seal swell due to the SBF was sufficient to block the system, (and it is one of the most probables in the factory diagnosis). I quickly pumped and relaced the SBF with one of the low hygroscopic DOT 4 fluids and have not had any problems since. I have installed a monitoring light under the dash which indicates when there is pressure in the brake system and so long as it goes off quickly I am happy that the 7% seal swell may not be permanent and shall hopefully have no further system lock-ups. Happy Packarding Peter Toet