I want to change my coolant before summer and i work at a chevy garage and we have a coolant flush machine that we use that does 95% exchange of the entire system. What my question is i know most of the engine is aluminum for this machine to work the engine has to be at operating temp with thermo opened, the machine sucks a pretty srong vacuum like 30 in hg and it puts in cold coolant to a hot motor which i know with aluminum is not a pretty good idea....anybody have any suggestion to a good coolant flush?????

 

pull the drain petcock out of the radiator and the block plug at the driver's side engine mount and drain both, put a garden hose in the radiator neck and flush out the radiator then replace the radiator petcock, flush again until the water coming out of the block is clean and let it drain then replace the block plug then fill with new coolant/water, this is a simple technique and works better than any flusher i have used.



edit: not that i have used a flusher on my 7 or would suggest it, the coolant drains on our cars are a very efficient way of draining the system completely and flushing them as well.