cooling system flush

[wildfelr]

RQB3263/81/305 .... i  WANT TO FLUSH 3263S COOLENT/HEATER SYSTEM .... when it warms up ....  There is a flush port in one heater hose.... appears original... that will allow me to attach a garden hose...... besides disconnecting the lower radiator hose what is the procedure for a complete system flush ?? thanks, Merry Christmas and stay warm up there ,  21 in melrose, florida

[Gunslinger]

Back in the '70s that fitting in the radiator hose was a popular aftermarket kit made by Prestone.  They may still be made for all I know.  It would have come with an angled pipe that snapped in in place of the radiator cap for coolant and water to exit...hint...stick a length of radiator hose in to direct outgoing coolant away from the car and not into the engine compartment.  

Get some engine flush...maybe not necessary depending on how long since the engine has been flushed and follow its directions to run it through the engine and cooling system.  Let the temps come down until you can safely open the radiator cap and release the pressure.  Then you can connect a garden hose up to the heater hose fitting, and with the heater valve open and engine running turn the water on to the hose.  As things run the fresh water will circulate and hopefully carry the scale and old coolant out of the radiator cap opening through the exit hose.  When the water finally goes clear you can stop the engine and turn off the water.

Now you should have a clean cooling system...but only filled with water now.  Leave the fitting in the heater hose open and pour in at the radiator cap opening (with the engine running again at idle) the appropriate amount of anti-freeze coolant for a 50-50 mix.  Displaced water will come out of the heater hose.  Once you've gotten the mix correct you can close the system back up and be good to go.

There are two things that you should consider before doing this...one is to open the radiator drain fitting at the bottom of the radiator to make sure it's not rusted shut.  Soak it first with penetrating oil before trying to open it.  This is only to make sure it won't be a future headache.  The other is this could be a good time to replace the thermostat just on general principles unless you know it's not old.  If you do replace it...get the fail-safe type...if it goes bad it is designed to do so in the open position so it won't overheat the engine and cause further problems.

There may be some YouTube videos on how to do this...look at some but remember not all advice on YouTube is good.

Edited December 25, 2022 by Gunslinger

[wildfelr]

RQB3263 .... THANKS i  got it all and just need warm weather .....HAPPY HOLIDAYS .... BILL in Fl

[mfg]

Well said Gunslinger!