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Discussion Starter #1
Hi all-

Going to do my first coolant flush on a 2012 JKU. I've searched EVERYWHERE and can not find the answer to this question.

Does anyone know where the engine block coolant drain plug is located on a 3.6 pentastar engine? I don't want to end up unscrewing the wrong bolt/plug.

The stealership is asking 150 for a full flush, but I would rather do it myself since I hear horror stories of the HOAT/OAT mixing.

Thanks,
MC
 

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I have not heard of one? Just drain the radiator.
 

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I do not find any coolant drain on the engine specified in the service manual.

The prescribed procedure simply states to open the rad cap (1) and then the rad drain (2) and let it drain.



Flushing is done via the rad hoses as well, so the closest thing to a drain would be the lower rad hose fitting.
 

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If you don't know where the freeze plugs are or, what they look like, it is better you follow normal flushing procedures thru the radiator hoses.
 

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how does one remove the coolant from the engine then if you just drain from the radiator?
I've had a lot of cars, but have never seen a drain in a block. The only thing even slightly close to that are freeze plugs. They're meant to pop and save the block if there is too much water in the coolant and it freezes. You don't want to be pulling those under any circumstance.

I have always just drained at the radiator petcock and filled, being comfortable with a 90% replacement. Never dealt with the fear of contaminated coolant though. I'd say eat the price of the flush if you're that concerned, its the only way you're going to know the heater core has been cleared. Perhaps just confirm the coolant the mechanic is going to use.
 

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how does one remove the coolant from the engine then if you just drain from the radiator?
Drain the radiator, close the drain plug and refill it with water. Run the engine for 30 seconds or so and drain it again. Do this several times until it drains out clear.
 

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Drain the radiator, close the drain plug and refill it with water. Run the engine for 30 seconds or so and drain it again. Do this several times until it drains out clear.
This the way I have flushed the system on various vehicles. To keep contaminants out of the cooling system I use distilled water instead of tap water when flushing.
 

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The only engine I know of that a block drain plug was the 7.3l Powerstroke Diesel. It had a bolt on the drivers side to drain the block.

Flash
 

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Discussion Starter #11
I've had a lot of cars, but have never seen a drain in a block.
https://www.youtube.com/watch?v=WOu_Si3gdbs

Fast forward to 2:17.

My concern is that if i run distilled water to flush the coolant. How do you get the water out of the engine block when refilling with antifreeze? the 50/50 premix stuff is tweaked if there is still water left in the engine block during a flush right... ?

Is removing the lower radiator hose at the engine block the same thing essentially?
 

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My concern is that if i run distilled water to flush the coolant. How do you get the water out of the engine block when refilling with antifreeze? the 50/50 premix stuff is tweaked if there is still water left in the engine block during a flush right... ?
That's why I always buy the concentrate instead of the premixed. I look up the specs for the total system capacity and then add 1/2 of that amount of pure antifreeze. Then I add distilled water until the system is full.
 

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That's why I always buy the concentrate instead of the premixed. I look up the specs for the total system capacity and then add 1/2 of that amount of pure antifreeze. Then I add distilled water until the system is full.
That's what I do. It's not an exact science but it has worked thus far. No frozen blocks or rusted cooling system.
 

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Fast forward to 2:17.

My concern is that if i run distilled water to flush the coolant. How do you get the water out of the engine block when refilling with antifreeze? the 50/50 premix stuff is tweaked if there is still water left in the engine block during a flush right... ?

Is removing the lower radiator hose at the engine block the same thing essentially?
How about that? Looks like an old 350 Chevy pickup. I had an S10 with a 2.8 and don't remember that having a coolant drain in the block, always just used the radiator drain. My wife has a new Traverse, I'll have to see if it has one.

Thanks for the link!
 

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My concern is that if i run distilled water to flush the coolant. How do you get the water out of the engine block when refilling with antifreeze? the 50/50 premix stuff is tweaked if there is still water left in the engine block during a flush right... ?

Is removing the lower radiator hose at the engine block the same thing essentially?
You're over thinking this. Adding some water to a pre-mix will not change the freeze temperature that much. Mix is good to -30F, 40/60 will move you to around -20F.
 
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