Q: broken crankshaft position sensor in block

Anything in the oil pan besides engine oil can cause severe damage to the engine. Pushing the remains of the crank sensor into the oil pan in hopes of it remaining there without causing damage is not advisable. Even the smallest piece will flow around the engine, potentially damaging internal components or even clogging oil passages within the engine. The proper way to do it, is to remove the oil pan to extract any remains of the broken crank sensor. Leaving remains of it in the oil pan will cost you a replacement engine versus the cost of removing the oil pan to extract it properly.