Installing a Cold Case radiator in Roadrunner and GTO. Need advice on flushing out old coolant.

Heating, Cooling & AC

  1. biomedtechguy

    biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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    My first thought is to remove the thermostat so I can run 100% water through the entire engine water passages to completely remove and flush the old mixture out. New radiators seems like a good time to replace the thermostats anyway, while "I'm at it". Thermostat removal required to allow the fresh water rinse throughout the engine, otherwise the thermostat would close, and the rinse would not be as effective.
    Am I missing something?
    Also I want to put in the absolute best thermostat available. Stant? Or??
     
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    • MarPar

      MarPar Swervin' Like Im George Jones FBBO Gold Member

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      • biomedtechguy

        biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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        • 68Moparmaniac

          68Moparmaniac Well-Known Member

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          Best of both worlds
           
        • biomedtechguy

          biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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          That requires cutting the heater hose to install the kits' T fitting, and the thermostat will still be closed. That backflow may still do the trick though.
          Anyone else?
           
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          • 68Moparmaniac

            68Moparmaniac Well-Known Member

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            It does the trick my friend. Just install the T's connect a hose to the T push the gooseneck into the radiator opening fire up the engine turn the water on and sit back and watch until it runs clear, your done.
             
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            • toolmanmike

              toolmanmike Moderator Staff Member FBBO Gold Member

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              It's best to have hot water, disconnect the upper hose at the radiator, stuff the hose in the hose neck on the radiator and turn on the water. With the engine running it will come out through the t stat and the upper hose and down the drain. Stant t stats are usually good but they do have a economy line. I always test mine in a pan of water on the stove and a thermometer to make sure.
               
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              • biomedtechguy

                biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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                Well having hot water under pressure would be a challenge, but I may be able to run a hose to my hot water faucet inside.
                I'm thinking it's a good time to change the thermostats, since I've never changed them, I have no idea how old they are or what temperature they open at.
                With the thermostat removed, and the housing replaced, I can run fresh water through the entire system, although the engine is running, it won't build pressure because of the continuous cool water supply from the "garden" hose.
                I am seriously considering the Evan's waterless coolant. I was absolutely going to use Evan's once I got my stroker built, but now is a good opportunity, what with 2 new radiators and the Pontiac 421 is still a relatively "new" build although it was done 3 years ago. Seems like going waterless would stop corrosion altogether.
                 
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                • 69a100

                  69a100 Well-Known Member

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                  If you feel really compelled to get the system really clean? There's 2 bolt looking things on each side of the lower block, pull those and clean any gradoo/crud out of the holes with a pick of some kind. Good Luck
                   
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                  • Billccm

                    Billccm FBBO Gold Member FBBO Gold Member

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                    My dad always used cascade powder and the garden hose. Two cups cascade, fill with water, idle or drive around with the heater running full blast. Once past operating temp drain, fill again to rinse, and then complete the repairs and fill with 50/50.
                    Dad did not like caustic chemical use in the cooling system and claimed the cascade rinsed out easily.
                     
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                    • threewood

                      threewood Well-Known Member

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                      I've done this a couple times...

                      *I pull the lower radiator hose to drain coolant completely. *Put the hose back on.
                      *Pull the thermostat out and bolt the housing back on.
                      *Remove the upper hose to radiator and attach a pipe +hose to the upper rad hose outlet. Long enough to get the coolant out over the grill. Plug the upper radiator inlet.
                      *Fill the radiator with water and put a garden hose in the water fill and turn on.
                      *Start the motor. Run until the hose out the front is clear. *Drain the radiator from the lower hose again to get all the water out.
                      * Put new thermostat in (Gates 33038, 180 degree / Stant 13478, 180 degree).
                       
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                      • 493 Mike

                        493 Mike FBBO Gold Member FBBO Gold Member

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                        There are many commercial cooling system cleaners available and using one with plenty of flushing afterward should be sufficient. I will add, buy some distilled water to mix with your choice of antifreeze. The thermostat will open for circulation and should not have to be removed. Just like oil, heat up the engine prior to draining. My 2 cents.
                        Mike
                         
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                        • 69a100

                          69a100 Well-Known Member

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                          I've always had good luck with Prestones radiator super flush or CLR. I pour a bottle in, go for a good drive, cool for a day, then repeat, flush, flush, flush. Good Luck
                           
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                          • ESOXER

                            ESOXER Well-Known Member

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                            • themechanic

                              themechanic Oklahoma is OK FBBO Gold Member

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                              Watch this and see how common methods fail to clean a lot of contamination and debris.

                               
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                              • themechanic

                                themechanic Oklahoma is OK FBBO Gold Member

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                                Here's the "good enough" way that will get most of the junk out.

                                 
                              • themechanic

                                themechanic Oklahoma is OK FBBO Gold Member

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                                • 1 Wild R/T

                                  1 Wild R/T Well-Known Member

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                                  How much work are you prepared to do?

                                  First step...

                                  Add one of these to the upper radiator hose for a few thousand miles.....

                                  https://www.amazon.com/Champion-Cooling-Systems-CCHF-1-50-Coolant/dp/B01FXRJ6R2

                                  Second step, as was mentioned pull the thermostat, disconnect both hoses & force lots of water through the block.... If you can inject compressed air to agitate the debris even better...

                                  If your really serious pop the rear most freeze plugs so the debris can drain from the lowest point, for water to come out the lower hose it has to go up about 2" from the bottom of the block coolant passages to the water pump passage to get to the lower hose.... Water does that fine, debris not so much.... Pop a couple plugs & you'll be amazed at what comes out....
                                   
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                                  • biomedtechguy

                                    biomedtechguy Accelerati Rapidus Maximus FBBO Gold Member

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                                    That filter looks great, especially the reviews. Too bad I didn't plan better right when I had the Pontiac 421 rebuilt, but I got the engine done the weekend Cruisin the Coast started.
                                     
                                  • 1 Wild R/T

                                    1 Wild R/T Well-Known Member

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                                    I actually have a Gano brand filter I use... I've had it for years & install it when ever I do an engine or radiator.... The Champion filter is nicer, the things I don't particularly like about the Gano the Champion addresses....
                                     
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