97OB>How to flush coolant system?

The easiest way is to let someone else do it but, if your a DIYer like me.
Get a large pan (> 2 gal) and lots of rags and one gallon of 100%coolant or
two gallons of premix 50/50 and 3 gallons of distilled water. Remove the
under cover. Unscrew to radiator drain (it's a pain) and as it's draing
remove the radiator cap. Siphon out the reservoir. Tighten the radiator
drain screw and refill radiator with distilled water. Run the engine with
radiator cap off and fill with distilled water as needed. Let engine run
until the top hose is HOT. Let engine cool and drain radiator again. This is
probable good enough if the drained distilled water looks clear and if not
repeat this step. Now there is some water still in the engine and if you
want a 50/50 % mix then get a clean gallon container you can pour from and
mix 60% coolant and 40 % water and add to the radiator until full. Start
engine and run to hot while adding coolant mix as needed. when the top hose
is HOT (thermostat open and coolant has circulated turn the engine off and
let cool. When cool top up radiator and tighten cap and add to the coolant
bottle. Keep an eye on the temp gage for a couple of heating/cooling cycles
AND check the coolant level in the overflow bottle. ed
 
The easiest way is to let someone else do it but, if your a DIYer like me.
Get a large pan (> 2 gal) and lots of rags and one gallon of 100%coolant or
two gallons of premix 50/50 and 3 gallons of distilled water. Remove the
under cover. Unscrew to radiator drain (it's a pain) and as it's draing
remove the radiator cap. Siphon out the reservoir. Tighten the radiator
drain screw and refill radiator with distilled water. Run the engine with
radiator cap off and fill with distilled water as needed. Let engine run
until the top hose is HOT. Let engine cool and drain radiator again. This is
probable good enough if the drained distilled water looks clear and if not
repeat this step. Now there is some water still in the engine and if you
want a 50/50 % mix then get a clean gallon container you can pour from and
mix 60% coolant and 40 % water and add to the radiator until full. Start
engine and run to hot while adding coolant mix as needed. when the top hose
is HOT (thermostat open and coolant has circulated turn the engine off and
let cool. When cool top up radiator and tighten cap and add to the coolant
bottle. Keep an eye on the temp gage for a couple of heating/cooling cycles
AND check the coolant level in the overflow bottle. ed

I'm not sure about the OB, but my WRX has a drain plug on the bottom
of the engine block that allows you to drain all the old coolant that
normally is trapped behind the thermostat and difficult to remove.

I put some black permatex on the threads as a sealer when I put it
back, but any automotive thread sealant should be adequate.
 

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