It's a self-bleeding system. If the vapor vent line is plugged, though, it can lead to cavitation of the pump and air in the system. Search the forums for vapor vent line and I'm sure you'll find plenty of information from bbob about how to find out if it's plugged and how to un-plug it.
does anyone know how to bleed the northsatr coolant system
There is no need to bleed it. Just slowly fill the system thru the pressurized surge tank pressure cap fitting. When full, start the engine and rev it to about 4000 RPM and back to idle slowly several times. This will purge any air out of the system. Refill and put the cap on. That is all that is required. If some symtoms of the water pump "vapor locking" then find the 3/8 hose at the pressurized surge tank. Disconnect the 3/8 hose when the system is cold. Coolant should stream out of the nipple on the pressurized surge tank when it is disconnected due to the fact that the nipple is below the level of the coolant in the bottle. If not, then inspect the nipple for plugging. Start the engine momentarily. Coolant should stream out of the 3/8 hose from the engine toward the surge tank. If not, then find the obstruction in the vapor vent line (the 3/8 hose) and repair.... The vapor vent circuit starts at the nipple on the water crossover just beside the upper radiator hose at the engine end. The 3/8 hose is installed over a hollow bolt that serves as the vent for the water pump cavity and a nipple for the hose. If you disconnect the 3/8 hose from the nipple at the upper radiator hose location and start the engine then coolant should stream from the small hole in the nipple/bolt. If not , then remove the bolt/nipple to fine out why it is plugged.