Zay et al, Coolant tank follow-up: As Kneale has mentioned, you could have a defective cap that allows overpressurization. And as Steve alluded, the newer tanks don't seem as robust -- however, are we talking OEM or modifield 5k/100/200 tanks? The V8 ones, while more $$ seem to be better made IME. Just an observation. Ingo