Last month took '93 245 auto trans up to 11,250' on a steep, rocky 4 wheel drive Colorado road. Had been to same place before and didn't remember road being quite so steep/bad (in hindsight, last time was in a 4wd). Crept down upper 1000 vertical feet (4 wd section) in 1st gear, and riding brake (no choice) letting up whenever possible. Brakes started to feel a bit spongy with about 100 vertical feet to go. Pumped a couple times and was losing pedal. Pulled over at bottom, pumped, and pedal completely gone. Popped hood. Fluid was spurting out of reservoir cap breather hole. Covered pinhole with finger since didn't know how much fluid already lost and waited half hour for it to cool down. Still way up in mountains, no cell reception, darkness approaching so when appeared to have most of pedal back, slowly headed on down 2wd road, in 1st and 2nd gear. Another 15 minutes or so later, had full pedal back and brakes/fluid seem fine. Lesson: just because can get up something, doesn't mean can safely get down.
Questions:
If I ever get into a similar situation again, what could be done to lessen the potential for serious consequences? Stop completely several times on way down? Use emergency brake? Due to altitude, did pumping actually worsen the situation by introducing air into system speeding up boilover? Did the altitude change itself on descent, even without pumping, contribute/worsen condition?
Thanks.