What are the symptoms of the main bearing going out?

[Jason Broussard]

I want to start with thanking everybody for their help and suggestions when 
I had the coolant line burst. It turned out that no head gasket damage 
occurred. All the smoke was from a collapsed PCV hose. With that said onto 
the newest problem.
My 91 200 20V has a knocking coming from the oil pan. Actually sounds like 
something is hitting it from the inside.  The sound has a patter of three 
quick knocks followed by a second or two of no knocking, then repeated 
again. Is this a sign of the bearing spinning?
TIA
Jason