Girlings and Chemistry Brake Booster Fluid

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Not being a chemist has it's drawbacks. One of my Girling servo re-builds came back (2 days old) with pregnant seals. These things are a full 1/3 larger than should be, but did not soften as I've seen before. The drag on the control valve created the usual release issues. Owner (a Volvo guy) admits to bleeding and topping off the system with whatever was in the garage, but then tossed the empty containers. I'm now soaking some good used seals in a variety of witches brews in an effort to dope this all out. I've heard, but not been able to verify, that certain suppliers have sourced matching seals that may have alternate compounds ?? Any added knowledge out there ?

 

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Chemical Update

ATE Super Blue Racing Dot 4 (says you can mix it with all Dot 4's and 5's) does not like Castrol LMA and definitely expands the seals. I tried good used seals in the mix and some new seals with the same results. The photo shows normal seals on the bottom control valve, while the seals on the upper show expanded flares that create friction and retard the valves movement. More info as the petri dish coughs it up . . . . .