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Simple 3-step complete coolant drain


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Hi guys,Just want to share with you I've found a simple way to drain all the 6 gal coolant out. I've looked at other DIYs and even the factory procedures but they all involve disconnecting coolant hoses that are under the car, which requires removing the underside panels. I'm too lazy so I studied the coolant diagrams and came up with a much simpler way.The total capacity is ~6 gal and you will drain ALL of it if you follow the steps below. Real simple.1) Remove the coolant reservoir cap and open the coolant drain plug at the bottom of the engine (SOP) and out come ~2.5 gal - all the coolant trapped in the engine block. Now put back and tighten the drain plug to seal the system.

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2) Put a 5gal bucket under the big hose connected to the thermostat. This hose is the coolant return hose from the radiators in the front. Disconnect the hose and out come ~0.5 gal. Now this is the fun part. Introduce compressed air to the coolant reservoir neck (a few PSI will do. DO NOT EXCEED 10 PSI. I used a simple rubber gasket to seal it). Be prepared, 2.5gal will gush out with force from the big hose - Congrats, you just drained all the coolant trapped in the front radiators! Basically the air goes into the radiators via the vent hoses and forces the water out from the big return hose.

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3) After steps 1 and 2, you've already drained 5.5gal (>90%) so you can stop here if you're lazy. For the perfectionists, of course we need to track down that remaning 0.5gal. Where the heck is it????You guessed it.....it's trapped in the heater core!! There's no valve. Forget about turning ON the heat when draining, etc. The coolant just recirculates the heater core whenever the engine is running. Now go disconnect the heater core coolant supply line from the engine and remove the two bolts holding the hard metal line so you can tilt down the hose like below. Remove the drain plug again and introduce compressed air at the hose side. 0.5gal will gush out from the drain plug and from the metal flange where the hose is connected to. Note this is the ONLY way to drain the heater core because the IN/OUT hoses connected to the heater core are at the top of the core. You can disconnect hoses all day long. Without force, the coolant will just sit at the core.Now go reconnect the two hoses and tighten the drain plug and you're done jumper.gifSo in summary, the engine holds 2.5gal, the radiators and hoses under the car hold 3gal, and the heater core holds 0.5gal. There's your 6gal smile.gifI used the cable operated hose clamp tool and a pick to break the surface between the hose and the metal part. Took me at most 5 minutes to disconnect each hose, if that. i think with practice, you can finish the above within 1/2hr. Note you need the uview vacuum tool to refill now that you've replaced all the coolant with air.

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Edited by Ahsai
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Yes, that's why I mentioned a few PSI will do. The steps above also made sure there's always an outlet for the coolant to be pushed out before introducing air. So practically the system is never sealed hence minimal pressure build up.

Ok, warning added in the oringal post.

Edited by Ahsai
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When i had the car totally apart I collected maybe a half gallon more than 6 gal. Maybe 99 MY is different?

Oh I see. Thanks for the data. I measured mine using a bucket so that may not be very accurate. Even with compressed air, there will always be some residual coolant here and there. At least I'm happy that I was able to drain the radiators and heater core easily, which normally requires a lot more disassembly.
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Yes it is a PITA to rip out the radiators and heater core.

But once you do (assuming the engine is out) all of the hoses have an open end. So you can simply force air through the end of every hose and all of the coolant will drain out of them without worry of damaging anything. I did this, and drained every drop of water out of the car. It turned out to be over 6 gallons, but I can't remember the exact figure off hand. If you have intermix (which I didn't), at this point you can flush to your hearts content, force a huge amount of water and cleaner through the hard and soft pipes. Or just replace the soft pipes since they are cheap. The hard pipes on the other hand are probably more expensive (not to mention difficult to replace).

That being said, I like your method! I guess at low enough pressure it would be safe enough.

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