Ok I understand it essentially means your engine is toast.. but what actually happens when an engine throws a rod?... what causes it and what does it damage?... I always wondered...

 

rod broke, rod bent too might count

 

ok rod referrs to a connecting rod. this is the piece that connects the crankshaft to the piston. if this breaks the rod then flails around in the crankcase until it breaks through the block typically.

 

I saw a 4.3 in a S-10 Blazer self destruct not that long ago. Mechanic was revving it up a little with the rod knock and around 2,200 rpm it let loose lol bye bye oil pan The wrist pin was actually sitting on the frame hehe and other parts were everywhere. The coustomer drove about 300 miles with a bad rod knock up and down hills and on the freeway before getting it to the mechanic.

 

when you get rod knock, has the rod actually broken at this point or is just loose or something?

 

Rod Knock - excessive bearing clearances. (rod not broken)
too much clearance between the rod bearing
surface and the crankshaft journal surface. the
bearing fits "loosely" over the crankshaft's journal as
the piston moves up and down. hence the
"knocking" noise.

Thrown Rod - See above posts. (Not Good At All)

Edit: See Tom's Post Below.......

 

here's an example of a thrown rod. When this happens, just plan on savalaging your exhaust, intake and heads if you're lucky enough to not crack a chamber like I was was. The rod cap is on the left and a rod bearing is on the right.

 

another