SST1 = big f@$king hammer, ie 1kg + head (everyone should have one in their toolbox). i have never failed to shock a crank bolt off yet, even without locking the flywheel.
i have never stuffed a radiator fortunately, but have come close. i have forgotten to remove a spanner i was using to turn the engine over whilst setting valve clearances before. i was lucky and just bent some fins, but didn't puncture the rad. funny how well you learn from your mistakes.