Coolant flush question

isaac2098

isaac2098

TJ Enthusiast
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Joined
Dec 28, 2018
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192
Location
Connecticut
My check gauges light has come and gone the last 2 days and engine temp has been fluctuating between 210 and deep in the red. I am going to do a coolant flush and refill with Zerex G-05. Can someone help me understand after I flush the radiator, heater core, and engine block do I refill with the 50/50 version of Zerex or the concentrated version then dilute myself with distilled water?
 
My 06 calls for 10.5 qts so 5.25 qts of coolant and 5.25 qts of distilled water it is. Can I pour all the coolant in first then the the water or should I premix them and do all 10.5 qts at once?
 
pagrey said:
Replace the radiator cap, it's cheap and Stant needs your money. Nothing to do with your post really but it's just good cooling system eidiquite.
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I plan on doing a complete cooling system overhaul in a few months if the flush and new coolant fixes my overheating issue I've been having daily
 
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Drive it the max time recommended on the flush instructions for the best results. I drove mine for 8 hours total and it cleaned out a bunch of crud. My antifreeze had been changed regularly throughout it's life, but never had a flush used until I bought it.
 
isaac2098 said:
I plan on doing a complete cooling system overhaul in a few months if the flush and new coolant fixes my overheating issue I've been having daily
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When I purchased the '01 TJ I flushed the cooling system and added fresh coolant in preparation for the summer months. Within 2 weeks the radiator started leaking and I replaced the radiator and cap (should have replaced water pump too). Approximately 3 weeks later the water pump seal started leaking.
Generally I do a complete cooling system service to start fresh when purchasing a used vehicle, but due to where I was living I could only do basic vehicle repairs. The coolant was replaced three times instead of once.
When you do a thorough flush on a system (old radiator and water pump) that hasn't been maintained very well; you will probably see the radiator and water pump seals start leaking in a few months since the gunk that was removed was keeping the seals from leaking.
 
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I just purchased the 8mm socket attachment so I can drain the engine block too. I have to wait a day for that to come in so in the meantime I just topped off the radiator with distilled water and it took about 3/4 of a gallon. The Jeep is already running much cooler and normal so I wish I had done that sooner. I took a pic of inside the cap before I topped it off, what do you guys think of this?
72AFF095-056A-4850-80B8-FF1865B199B2.jpeg
 
isaac2098 said:
My 06 calls for 10.5 qts so 5.25 qts of coolant and 5.25 qts of distilled water it is. Can I pour all the coolant in first then the the water or should I premix them and do all 10.5 qts at once?
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When I did mine, I added all my coolant then went to add water and could fill it all. I assumed because sone of the coolant was still in the lines when I drained it it didn’t all come out
 
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Jerry Bransford said:
That looks good under the radiator cap. I would not bother draining the block.
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Thanks Jerry. So how do I go about knowing the right 50/50 mix? I saw somewhere on a different thread Blaine was saying that it is not a true 50/50 with the engine fluid not drained.
 
Hey flush it completely and your heater core. Might as well do it 100%. Replace the thermostat get some new hoses. Plenty of things you can do before you put back together. I soaked my head and block in diluted acid and removed all the crude from POs using tap water. when i flushed my radiator so much gunk came out i just bought a new one. If something becomes dislodged in your cooling jackets it might cause and issue. With the lower hose disconnected and thermostat out use distilled water to flush the block. you can always flush out the excess distilled when you put in your mix and be tip top.
 
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isaac2098 said:
Thanks Jerry. So how do I go about knowing the right 50/50 mix? I saw somewhere on a different thread Blaine was saying that it is not a true 50/50 with the engine fluid not drained.
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It doesn't have to be a precise 50:50 mix, and it does depend on the ratio of the leftover coolant still in the block. For me and in my typically warm/hot climate conditions, I'd rather err on having slightly more distilled water in my coolant mix. Water cools better than antifreeze. I consider my antifreeze to serve as a preservative and lubricant for the pump.

But in CT where you live I'd try to achieve a 50/50 mix. It's easy to know what your ratio is with either a specific gravity coolant tester or (better) an antifreeze refractometer. Either is inexpensive to buy at an auto parts store. Top it off and run it for a while to get it mixed. Then test it and if it's not close enough, drain it some and add either water or coolant as needed to get it to the desired 50:50 mix.
 
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