Are there any signs/symptoms that can be observed if a main bearing is going bad? Does it make any sounds? Do you notice an increase in oil burnage, drop in oil pressure, loss of power? Anything that can be observed before the thing lets go and demolishes the bottom end?
And if so, how long does it take from the time a symptom is observed until something catastrophic happens (I suspect this will be a WAG, so feel free to guesstimate).

 

drop in pressure.

 

^ idle, driving or both?

 

theoretically both. looser clearance between the bearing and journal causes a drop in pressure. same flow from the oil pump over more area = less pressure. I would recommend hooking up an external pressure gauge and checking.. you can rev the engine and check the pressure at idle and load.

It can also make a noise, but I wouldn't know how to describe it

what leads you do believe you have a worn/damaged bearing?

edit: I meant to say MORE area, not less

 

When your oil light flickers at idle, its too late ( i know from experience )

 

what causes the main bearing to fail?

 

Well, my motor has a bit of a sordid past. I had some Toda cams that had the nose of the lobes sheer of in the motor. Didn't see any problem at the time, but all that material had to go somewhere (and I'm sure it wasn't all picked up by the filter). I've also had significant timing chain tensioner issues (I'm on my 3rd one and the car has <17K miles on it). Additionally, about the time I was about to replace my most recent tensioner, I started hearing a soft screeching noise at the front of the motor. I can only really hear it at idle, usually when the motor is warm. I played it off as some side effect of the TCT issue, until I saw this thread:

https://www.s2ki.com/forums/index.php?showtopic=482282
and one of the first responses:
I haven't seen the final diagnosis (other than the broken baffle in the oil pan), but it looks like it's going to end up with a spun bearing due to oil pump blockage.

Really, I guess I just wanted to find out if my whine/screech could by a symptom of a bad bearing, or if it's likely something else (probably still related to my TCT issues).

 

do u mean just idling, or when you start it up? Because when i start my car up, sometimes it blinks then goes away. Then sometimes when i JUST START it up and the oil light is still on, i hear ticking but it goes away as soon as the oil light goes away. is this normal?

 

When you start the car, it's normal for the oil light to come on momentarily 0.5-1 seconds (and maybe flicker once). The ticking may be the beginning of TCT problems, or it may also be normal (as the TCT needs oil pressure to work, too). There are plenty of threads about the TCT around here. If you need more info, just do a quick search. Also, it's possible that the ticking is not TCT related.