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Old 01-16-2020, 02:02 PM
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94 4.0L coolant info

Hey guys. So I put Prestone Antifreeze/Coolant (yellow jug/black label) into my cooling system recently when I replaced a leaking radiator and drained (not flushed) the system to do that. I since have discovered that, even thought it's pretty green, that this is Prestone's "yellow" OAT coolant and I should've put in green IAT coolant. I actually was about a quart low (after a small hose clamp leak) recently and added real green IAT (mixed 50/50 with distilled water with all coolant additions) to adjust the level.

1) What do I do now? Do I leave things alone until spring to do a complete flush and refill with green?
2) Do a complete flush now (at a shop) and refill with green?
3) Some other suggestion?

Thanks for any help on this. I heard of a few people that their water pumps went from using the yellow coolant (no lubricating silicates present) when the green (with silicates) was factory fill.

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Old 01-16-2020, 02:28 PM   #2
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Change it...
https://www.wranglerforum.com/f290/w...l#post34260959

The method I use to flush is buy 8 or so gallons of distilled water, fill, run, drain and repeat until I am satisfied.
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Old 01-20-2020, 01:58 PM   #3
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Change it...
Thurs fri sat... all gonna be in the 40's in boston and that's PLENTY warm...

To flush, with a COLD engine remove the thermostat and disconnect the upper hose from the radiator....
Put your garden hose in the upper neck of the radiator and direct the upper hose to the side...
Turn on the garden hose and start the jeep... the garden hose will supply more than enough water at idle and each time the radiator gets full, goose the throttle to blow the nastiness out the upper hose....

Continue till nothing but clean clear water comes out....

Then drain and fill w green at 50/50... distilled is 'best'.... I've used tap water for over 30 years without a single issue and would not waste my money on anything else...
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Old 01-20-2020, 10:55 PM
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Don't I want to drain the coolant that's in there first as much as possible, fill with tap water, then start the process? If yes, would it be better to flush the system first in reverse flow with the hose and disconnect the lower hose and flush the radiator separately? I haven't done this on a Jeep motor before, but what should I use when putting back the thermostat to prevent housing leaks? Thanks.
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Old 01-21-2020, 12:13 AM   #5
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If you use my process you don't have to do anything else... you can drain it first if you want or it will rapidly pump itself out...

When you are done and you put the thermostat back in you need to use a new gasket just like any other time you install a stat.
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Currently in the stable: ... 97 tj 4.0 5 speed stock....04 tj 4.0 auto 4" and 33's... 98 tj roller for future build... 94 yj sahara 4.5" RE and 33's... 92 yj sbc 3/4 ton axles and 38's... Cj5,7,yj,xj,ex mud dragster project

TJ dash speakers that actually rock! Kicker sub and amp in center console
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Old 01-23-2020, 12:07 PM
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Garden hose into the opening of the radiator that I just pulled the hose off of or remove the radiator cap and add garden hose water to there?

Do I need to put heater on and fan on high also?

I should probably collect the fluid coming out of the radiator hose for disposal too, 'cause that is where it would be expelled from, right?

Sounds like this way would do a nice flush out and not take all day with heating and cooling, etc. Thanks.
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Old 01-23-2020, 01:25 PM
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Just found out that Prestone still makes a green IAT coolant for the older engines but it does not contain the water pump lubricants that their older green formula had. They recommended me to use the newer yellow OAT coolant in the 94 4.0L engine. Does anyone have experience using the yellow coolant in their 94 or older engines (any problems, rust, scale, leaky water pump over time, etc)? Thanks.
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Old 01-23-2020, 03:20 PM   #8
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Stick with the green stuff, if you scroll through the link I provided earlier you will see what can occur with yellow.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
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Old 01-23-2020, 05:48 PM   #9
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You can pull the cap if you want so you can see in but put the hose in where the upper hose goes....

I just run it out in my gravel driveway where it can evaporate or soak in...
The only issues are if it pools and animals drink it or it goes into a sewer or storm drain...
Diluting it w 50 or so gallons of water further protects animals from poisoning...

Antifreeze is biodegradable

If you live in a concrete jungle maybe drain and collect what you can before flushing

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Currently in the stable: ... 97 tj 4.0 5 speed stock....04 tj 4.0 auto 4" and 33's... 98 tj roller for future build... 94 yj sahara 4.5" RE and 33's... 92 yj sbc 3/4 ton axles and 38's... Cj5,7,yj,xj,ex mud dragster project

TJ dash speakers that actually rock! Kicker sub and amp in center console
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