Hello, I’m looking for some help regarding my Shimano Casitas 150HG. The reel casts fine, but when I turn the handle to reel it makes a somewhat loud noise. Im pretty sure it’s the bearing but my question is what bearing should I replace? And does anyone know the size? Thank you 

Could be something in the spool as well causing the noise. I have noticed that 90% of the time when I hear a "grinding" noise it is almost always something in the spool.

You think it’s “the bearing” but don’t know which one or the size, so start at the beginning. What was going on when this started? How much use has the reel seen? Has it been dunked or dropped in the sand? Is it constant or at a certain point in handle rotation? These things are nearly impossible to diagnose sight unseen. Contact me directly if you want to try to address it or send it in and I’ll take a look. 

Could be anti-reverse bearing. Had happen to my Ryoga. If so, not very difficult to correct (clean and re-lube).

Plenty of vids out there showing how. Look for red/brown "rust dust paste" in the bearing and on the bearing sleeve.

 

Karl