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[racoondp]

1980 bmw 320i, overheating problem-radiator was very dirty, Replaced with new radiator, new thermostate, flushed system thoroughly, replaced antifreeze, run engine to proper temp, turned on heater, test drive/run around town (stop/go), every thing seemed ok. Later same day as weather temps (from HIGHs in 90s) were beginning to cool, attempted to go up a 7mi. grade (to Willits, Ca). to work. After work, going back home, aprox. 2miles distance across the ridge before decending the grade, the temp gauge began to go up quickly-pulled off the road/parked just as it hit red. Allowed it to cool, it took on aprox. 16oz. bottled water and was able to get it back to work (2 mi or less). Parked, opened hood and the top radiator hose was buldging, not leaking but definately lot bigger than it should have been. Replaced radiator cap, water has visible movement within radiator. Fan between radiator & engine is running.

My questions: having been told to purge the cooling sytem completely so no air is in system. Don't know where the 'air' is purged from -'bleeder valve' or 'nipple' are names that I've heard. True??? if yes WHERE is it located? & how is it used?

The hoses all have been said to be good, even though not sure about the one that swelled.
I need to have more explaination on possible solutions. What now????