No, but they can cause it to overheat
You may have air pockets trap in the cooling system.
yes
The cooling system
Back flushing on a cooling system is when you get all of the trapped air out of your cars cooling system. This will make your vehicle run better after you do it.
Have you done a rebuild? Is this why your trying to purge the cooling system? Typically you will need to run the vehicle till the temp gauges reads near overheating, then allow the vehicle to nearly cool and remove the radiator cap. This allows air pockets to be pushed through the system. You can also run it to normal operating temperature and slowly crack the radiator cap allowing the system to expell excess pressure.
Air in the system. Bleed the cooling system and remove any trapped air pockets.
Should bleed all vehicles after the system has work done to it to get rid of air pockets
PCV Valve
PCV valve
PCV valve
To avoid over heatig
There are cooling systems for the engine and the transmission. These are separate, and necessary to keep the vehicle from overheating.