Re: Dumbest mistake ever.
You're not alone. My beat-up '82 C10 (250 L6) had a coolant leak & I topped it off with water. It got dipped down into the 20's a month or so ago & I now have a steady stream of water coming from the flywheel area...looks like a rusty core plug gave way.
A couple years ago I let a V6 Fiero freeze but its damage was a water pump: the ice somehow forced the pump shaft seal out.
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J  el
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