I've done this several times on several different vehicles, including my '84 years ago. It's an emergency measure to get out of trouble, and even to get to a nearby shop.  But not more than that.

Plastic parts simply were not engineered for 25+ year life spans in cooling systems.  They will all get brittle and fail sooner or later, and it's already later for the original parts on our vans.

Stuart

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related: what kind of luck have folks had running the vanagon with the cooling system unpressurized?  I've done it but only for less than 10 minute drive.
Edward