I fail to see how any modern engine can suffer catastrophic failure as a direct result of being rotated backwards. Timing belt drives, for the most part, have hydraulic tensioners which are easily able to overcome any "reverse tension" that may be applied. TIming chain tensioners are much the same: they have built in safety locks which prevent them from collapsing.
In fact, when replacing the timing chain tensioner on a Toyota 1ZZ, the actual factory procedure is to remove the original tensioner, install the new LOCKED tensioner, and rotate the crankshaft slowly counter-clockwise while listening for a distinct "CLICK". Once the click is heard, you rotate the engine 2x in it's normal direction and fire it up.
In fact, when replacing the timing chain tensioner on a Toyota 1ZZ, the actual factory procedure is to remove the original tensioner, install the new LOCKED tensioner, and rotate the crankshaft slowly counter-clockwise while listening for a distinct "CLICK". Once the click is heard, you rotate the engine 2x in it's normal direction and fire it up.
