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Old 03-22-2018, 09:23 PM
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Not the usual antifreeze question

I'm soon installing a new radiator in the 2009 JKU sahara. A crack in the plastic up tube on the drivers side has started to become a problem ( sidebar... JB weld worked for a few weeks to buy me time to order the OEM replacement)
The old radiator is filled with Prestone Green it is compatable and HOAT.
When the old radiator is removed, hoses drained... I understand there is still some fluid in the water pump, heater core and engine...
Question 1 - how much fluid is left? 1/2 gallon? a quart?
Question 2 - I am wanting to fill the new radiator with Zerex HOAT "approved"
are there any issues with the mixing of these two same
as I am not planning on a flush
Thx for the advise that is sure to come.

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Old 03-22-2018, 10:52 PM   #2
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I would not take the chance if it was me. Has I understand it the way to flush this system is not hard. Drain radiator, fill back up set heat to high and start the vehicle, I kept my radiator cap off doing this. Once to operating temp shut off and drain again. Repeat one more time and the system system should be pretty clear of coolant. You can always repeat if you still have color. You might also consider changing your radiator hoses. Even after just 4 years mine are pretty swollen.

FYI: I get to do this on Sunday I think if all my parts get here by then.


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Old 03-23-2018, 01:38 AM   #3
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Since you will be starting with a new radiator and only a little old coolant trapped in the system, I would just cycle water through it twice. Then put the proper amount of pure coolant in to reach the 50% coolant/water mix (based on listed capacity) and then top of with water to reach the 50/50 solution (unless you want it stronger). Then you should be good to go.
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Old 03-23-2018, 07:02 AM
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Thanks for the replies. I am guessing that maybe a few quarts are left in the system. I just don't know for sure.
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Old 03-23-2018, 08:58 AM   #5
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Originally Posted by Scuba591 View Post
Thanks for the replies. I am guessing that maybe a few quarts are left in the system. I just don't know for sure.
These are all good suggestions and if I may, its advisable to use distilled water in you mix, maybe it was mentioned and I missed it.

Does anyone know if the block has a drain on the Pentastar engines or the OPs I'm past the post and cant look back at his MY. Those are handy and really help purge the old stuff
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Old 03-23-2018, 06:19 PM   #6
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Buy a flush kit. They're pretty cheap. I attached a piece of old garden hose to the discharge tube using heat shrink. works good. keeps the mess to a minimum. run it until everything that comes out is clear. Drain it well, and use distilled water to mix the new antifreeze 50/50. You'll need to cut in a "T" to connect the flush hose (supplied in the kit, just follow the directions). Hang on to the discharge connection, especially if you hooked an extension hose to it, and you'll be able to use it again. (Antifreeze don't last forever. Good idea to flush and replace every few years)
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Old 03-23-2018, 06:32 PM   #7
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Through all my reading and research, draining the radiator and reservoir will leave roughly 50% of the capacity in the remaining areas. After you replace the radiator fill with distilled run to temp drain and repeat till your clear of color. drain the radiator and reservoir a final time and fill with undiluted coolant(not 50/50). Running a final time will leave you at recommended 50/50.

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