what is the purpose of bleeding the coolant system, i know its suppose to get rid of the bubbles going through the coolant system, but where do these bubbles come from and what can they cause as far as engine temp?

 

they'll most likely give you idle surge issues, and throw your temp gauge off because theres not a constant stream of coolant flowing past it.

 

air heats up quickers than water does, so when the air passes the the part that measures the temp, as the air will be hotter than the water, the reading will be somewhat wrong

 

The bubbles mostly are trapped air, causing an inability to completely refill everything with coolant after draining it for whatever reason. You don't want bubbles in your engine. A bubble will cause a hot spot, and that could lead to cracking the head or block.