Quote:
Originally Posted by Laird Scooby
Not an ideal way to do it IMHO - better to fill the system with plain water, run it up to temperature to ensure no leaks and the engine does what it should responding to temperature changes by altering mixture, idle speed etc then add a cooling system flushing agent when cool enough to do so safely.
Again, run it up to temperature as per the instructions on the flush (each seems to differ slightly) and allow to cool again.
Then remove the top hose and thermostat, refitting the 'stat housing without the 'stat inside. Refit the top hose to the 'stat housing but NOT to the radiator. Insert the garden hose into the "free" end of the top hose and turn the hose on, leave for at least half hour or until the water runs clear.
This will back-flush the system completely and is mainly just water at this point.
Once it runs clear, switch the hose off, remove it and refit the 'stat and top hose. Remove the bottom hose from the rad to drain the water from most of the system - some will remain. Refit the bottom hose and now add the correct amount of concentrated antifreeze to the cooling system, topping up with water as necessary.
Refit the cap on the expansion tank, run the engine to temperature and allow to cool. Check the level again once cool, topping up with water as needed - don't forget the right amount of antifreeze is already in there. Keep an eye on the coolant level for a few days, it shouldn't alter appreciably but may need a little more water once the air locks purge themselves completely.
For those about to scream that you can't put cooling system flush down the drain, most are based on caustic soda, the same stuff used for drain cleaner. Some modern ones use a more natural mix of other things that are safe to go down the drain. The rest should be just plain water.
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Ha! Ha!.........you did get the wrong end of the stick??
The simple reason one doesn`t put the water in before starting is to make sure the engine starts and does not misfire due to water seeping past a faulty head gasket or if the mechanic has not torqued the bolts properly or in fact anything to do with head gasket replacement including didn't get the head skimmed???
Air in the coolant system is a completely different operation to take care of.