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Discussion Starter · #1 ·
Hello all. I’ve read through many of the coolant flush procedures on this site and still have a few remaining questions. I have a leak in my radiator and will be replacing with a new mopar radiator and plan on replacing the radiator hoses, T stat, and mopar water pump at the same time since all the fluid is getting replaced. I plan on using Mopar fluid and distilled water. My question is how can I achieve the best flush with just distilled water, no hose to not introduce tap water in my cooling system. The sad part of all of this is the dealership parts guru gave me a blank stare when I asked if I should use distilled water. He looked at his coworkers laughed and said I’ve never heard that before. Use tap water. Anyway....

Since I’m replacing the radiator I planned on draining it, then draining and flushing the heater core both ways with a funnel and distilled water, then I get a little lost at the engine block. I understand you can remove the temp sensor on the side and drain the block of coolant. Is draining the block sufficient to clean the system or at that point, should I fill everything back up with distilled water and run for awhile then drain it all again before replacing the new components?
 

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I would just fill it with distilled water and add a coolant flush like Prestone or Motorcraft VC9 then drive it for a week, drain, refill with distilled, drive another day, refill, drain, drive, repeat until it comes out clear. You might need to throw a piece of cardboard in front of your radiator to get it to operating temp if when running straight distilled and cleaner. Then drain and fill with about a 60/40 mix of coolant and distilled if you want to be at close to a 50/50 mix of coolant and water. I'd use ELC rather than Mopar coolant personally. If you live somewhere that is getting to freezing now you might want to just refill 50/50 premixed ELC and do the flush in the summer.
 

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Discussion Starter · #3 ·
Thank you for the info. We will be hitting freezing temps very soon overnight. This vehicle is not my DD. Sounds like it may be to wait until spring/summer to do the radiator swap and flush? Or would it be best to install the new radiator now, Then flush in the spring? If I do the flush on the old radiator my thinking is it could flush out a bunch of junk out of the old radiator that could get stuck in the heater core.
 

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Yeah personally I'd just do the new radiator now, fill it with a mix of coolant and water, then do a flush and refill in Spring. That way you'e just removing the crap from the block passages and the heater core and not worrying about what's in the old radiator.
 

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I took a little different (and slightly more expensive) approach. I had the system flushed and refilled first at a local shop. Made sure they refilled with proper coolant. Then I replaced radiator, water pump, thermostat and housing, hoses and belt in my garage. I did it this way for a couple of reasons.....1)it was January and I couldn’t use my hose to flush the system and 2) the flushing part is pretty messy and the pro’s get all the old fluid out. Good for you for using the Mopar radiator and pump....you’ll be glad you did. Take your time cleaning the pump mounting surface on the block.
 

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No need to use Mopar fluid. Use Zerex G-05 and distilled water.

Go ahead and flush with a water hose then assemble coolant hoses, fill the system with distilled water, run the engine to operating temperature a few times, and then drain the water. You can drain the mixture of distilled water and the tap water that was trapped in your engine block and refill with distilled water another time if you want to be sure to remove 98% of the tap water. Finally, drain and fill with proper mixture of Zerex and distilled water.


If it's freezing there, then you should wait until the weather warms above freezing for a day or two.
 

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Thank you. Is there an advantage of running Zerex vs. the Mopar coolant?

I don't think there's an advantage but the Zerex will prevent the need to go to the dealership to get it and will probably be less expensive.
 

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In my personal experience, I have always and only used the garden hose to flush EVERY vehicle I've ever owned. The places I've lived in have always had very good city, not well, water with very limited minerals in it. I usually let them run with a trickling hose stuck in the radiator fill with the petcock open and the engine running for about 10 minutes. Then of course back flush the heater core for good measure. The only place I use distilled water when refilling is in my motorcycles because the coolant stays in them longer and they seem to be a little more fickle related to hoses and seals.

There is another trick to be learned. If you know you want a 50/50 mix (or whatever ratio), add the correct amount of condensed coolant first into the radiator, then fill up the remainder with water. You could always add a splash of additional condensed coolant if you desire before adding the water. This will avoid the dilution of any water left over from the flushing. Then mix and fill the overflow container.
 

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When I replaced my radiator I first flushed with a garden hose until I got clear water. I believe it took three drains before the water was clear.

Then I replaced the radiator and did two flushes with RO water before I Installed the antifreeze.
 
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