Cooling System Bleeding Procedure
I'd like to know whether todays 'vacuum' cooling system flushing equipment can fully evacuate all the air from a system once it's been drained down. Specifically, relating to the GM 3.1/3.4 series fwd engines. On this engine there are coolant bleed screws on the themostat housing and one at the top of the riser on the LHS of the engine. I have been assured that the LHS screw need not be opened during the process, but then, precisely how does air trapped in there get removed by today's equipment?