Oh yea.. The crank pulley can separate. I've had a couple do that. A separated crank pulley just means the belt will not turn when the crankshaft rotates. In fact, on my last Maxima purchase, I went ahead and replaced the crank pulley because sooner or later the rubber damper will fail. The timing chain is steel. Yes our engines are interference engines.

Here's a picture of a separated crank pulley that I replaced a few years ago.

 

 

 

Correct. Also, the timing chain drives the water pump (behind the front timing cover) so if the serpentine belt breaks, the engine will not run hot. Eventually, you will drain the battery and the car will stop running.. But no engine damage will occur..

The timing chain and the water pump are behind the timing cover. Here is a picture with the timing cover removed.

 

It's possible that the seller thinks that this is a catastrophic problem. So he might sell it cheap.

That pully has nothing at all to do with valve timing.
No engine damage at all.

You just need to replace that pully with a new one.

 

 

 

Use the starter to loosen the bolt. With a breaker bar on the crank bolt and the handle resting on the groung turn the key for a split second. Easy fix, could be a great buy.

 

Don't know if you have an impact gun, but the bolt holding the pulley guns right off. Easiest way. Leave the belts on until you crack the bolt.

While there replace both belts since they have to come off and also do the front main seal (OEM). You're in that deep, so might as well. OEM belts and seal are very reasonable. YT has videos.

 

 

The pully IS the harmonic balancer.