This may be a longshot, but I'll just throw it out there for consideration. A stream of cold water on hot calipers with a torn boot could wick water in between the piston and caliper bore where it would not go during normal driving. Rust could then develop to hinder piston movement. But I would think that this would happen only on 1 or 2 wheels, not all evenly, so there would be a corresponding unevenness in braking.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.