Before removing the crankshaft, check the end play by mounting a dial indicator with the stem aligned with the crankshaft and touching one of the crank throws. Push the crankshaft to the rear and zero the dial indicator, then pry it to the front as far as possible to check the reading, which indicates the end play. If the end play exceeds the specified limit, inspect the crankshaft thrust surfaces for wear; if no wear is found, replacing the main bearings should resolve the issue. If a dial indicator is unavailable, use feeler gauges by pushing the crankshaft to the front and slipping the gauges between the crankshaft and the thrust main bearing to measure the clearance. Loosen the main bearing cap bolts three-quarters of a turn until they can be removed by hand, checking for markings on the caps, which are usually numbered consecutively from front to rear; if unmarked, label them accordingly. Gently tap the caps with a soft-faced hammer to separate them from the engine block, using the bolts as levers if necessary, and take care not to drop the bearing insert. Finally, lift the crankshaft out of the engine, ideally with assistance due to its weight, and with the bearing inserts in place, return the caps to their original positions on the engine block and tighten the bolts finger tight.