Question: picked up a low end knock after driving under normal conditions. ran and drove fine, but after sitting 30 minutes or so tried starting it and now it has the loud knock. Thinking either crank bearing or oil problem? oil is full and clean after recent change. 2000 chrysler sebring 2.5L v6 115k miles.
Answer: If the knock started all of a sudden, that would tell me something broke, spun, or got plugged up. Engine knocks usually start quietly then get louder over time.
First you would need to get the oil pressure checked with a mechanics gauge to rule out a bad oil pump. Next use a stethoscope to try to pinpoint the noise.
Cancelling out cylinders by removing the spark plug wire to cylinders one at a time can also give a clue to which cylinder has a problem. By causing a cylinder to not fire, this takes the load and stress off the bearings and will usually make the noise lessen or go away. Taking the engine apart would be needed to check all the bearing.
Another possibility is that for some reason, the flywheel broke. This can sound exactly like a lower end engine knock and I have seen many a good mechanic get fooled.