Ram 5.7Hemi Coolant Flush DIY

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Hemi395

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Since I didn't find a writeup on this and it was requested by a couple members here, I decided to make one. I would recommend doing a flush of the cooling system every 5 years if you're planning on keeping the truck for any length of time. The steps I outline in this writeup involve flushing the cooling system with distilled water but if you decide do a radiator drain and fill with the proper coolant every 2-3 years, flushing with water isn't necessary IMO.

**IMPORTANT**
- 2009-2012 trucks use HOAT coolant or the Mopar 5 year/100000 mile (Orange in color) coolant. It is very important to only use a HOAT coolant in these trucks. DO NOT mix it with the newer OAT coolant or a sludge will form and your Hemi will overheat!!

- 2013-2018 trucks use OAT coolant or the Mopar 10 year/150000 mile (Purple in color) coolant. Again, DO NOT mix OAT with HOAT coolant or a sludge will form and your Hemi will overheat! NOTE: this coolant will change color to a pink/orange color after its been in the truck for awhile so don't be alarmed if its not purple like the new coolant.

- If flushing with water, ONLY USE DISTILLED WATER! DO NOT USE TAP WATER! Distilled water is less than a dollar/gallon so there's no excuse not to use it!!!

-5.7 Hemi coolant capacity is 16 quarts (dry fill)


Supplies needed:

-I highly recommend a spill proof funnel for adding coolant and bleeding air out of the system. Makes for very little mess.
https://www.amazon.com/gp/product/B00A6AS6LY/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

-10+ gallons of DISTILLED water (depends on how many times you want to flush the system)
-Thread sealant (I used Permatex)
-3 gallons of Mopar concentrated coolant. I recommend the concentrate because its easier to get a 50/50 coolant mix. Plus its essentially the same price as the premixed Mopar coolant so why pay for water?
-1/4" hose for attaching to the radiator petcock drain. Not necessary, but makes for less mess.
-Rags or shop towels

Tools needed:

-3/8" allen socket
-1/4" allen socket
-Torque wrench that goes as low as 10 ft/lbs
-14mm socket for the block drain plug
-13mm socket for the thermostat housing bolts
-Pliers for the hose clamps
-Antifreeze tester

Start on a cool or better yet cold engine. A hot engines cooling system is under pressure and can burn you!

Drain the radiator: Take the radiator cap off and set it aside. Attach the 1/4" hose to the drain nipple and feed it into a container. Rotate the petcock counterclockwise using the 3/8" allen socket until it opens completely. You will hear coolant start draining into your container. The radiator holds about 2 gallons of coolant so plan your containers accordingly.

Next go to the thermostat housing. This would be a great time to change your thermostat since you will be taking the housing off the water pump. Loosen the bolts on the water pump and remove the housing from the water pump. Remove the bleeder plug next to the thermostat housing using the 1/4" allen socket. Pry the outer gasket off the thermostat and reinstall the housing without the thermostat but with the gasket in place. This will ensure water flushes through the entire block.

Locate the heater core hoses at the bottom of the water pump. Remove both from the water pump noting where they attach to. Be ready with a drain pan under it because all the coolant in the heater core will flow out. At this point I took 12psi of compressed air to one heater core hose to completely blow out any remaining coolant. This isnt really necessary as most of the coolant flows out on its own but it doesn't hurt to do. DO NOT USE MORE THAN 15psi of air! Replacing the heater core is a big job that involves removing the dash and HVAC assembly.

Remove the lower radiator hose and allow anything left to drain into a drain pan.

Next comes the fun part, the block drains. The passengers side block drain is perfectly visible. Remove it slowly and allow it to drain slowly. If the whole plug is removed you will take a shower in coolant. Trust me, not fun. The drivers side block drain is perfectly behind the starter and front diff bracket. I didn't have any tools that would fit in there at that angle so I wasn't able to drain the drivers side of the block. If anyone can figure that out please post what tools you used!

Once you're satisfied that all the old coolant is out (with the exception of the the drivers side of the block) reconnect the heater core hoses, lower radiator hose, and put in the passengers block drain plug. Leave the bleeder plug on the thermostat housing out for now.

Now is the time to attach the spill proof funnel to the radiator. Fill the radiator with distilled water until it comes out of the thermostat bleed plug hole. Its going to take close to 2 gallons of water before that happens. Once it comes out put the bleeder plug back in.

Start the truck and let it run at idle. Make sure the hvac temp is on heat. It will immediately suck the water down inside the radiator. Continue filling the radiator with distilled water until its full. It will bubble and spatter water out of the funnel as the air bleeds out of the system. When I did this my truck never got above 130* because there was no thermostat installed.

Rev the engine to 2000RPMs for a minute or so several times and then shut the truck off.

Begin draining the water out of the radiator just like before as well as the heater core hoses, lower radiator hose, and remove the thermostat housing bleeder plug again. Let everything drain and then move to the passengers side block drain. Allow that to drain just like before and the drivers side as well if you can get it out. Once you're satisfied with how much water is drained out, put the drain plug back, bleeder plug back, and reattach all the hoses. Fill again with distilled water, run the engine like before, and drain again. If the water is clear you're done flushing. If not repeat the drain and fill proceedure until the water is clear.

Once you're satisfied with the flushing process, apply thread sealant to the block drain(s) and install them back into the block. Remove the thermostat housing and remove the gasket you put in earlier. Reinstall it onto the thermostat and reinstall the thermostat. Torque the bolts to 10ft/lbs. Leave the thermostat bleeder plug out for now. Reattach all the hoses. There is still some distilled water in the system so if you only put premixed 50/50 coolant in, it will be diluted to a point and you wont have the
correct freeze protection. I mixed 3 gallons of 50/50, so 1.5 gallons of Mopar concentrated coolant. I used this for the initial fill. Just like before, pour 2 gallons into the radiator until it comes out the thermostat bleeder port. Apply thread sealant to the thermostat bleeder plug and reinstall it.

Start the truck and let it idle. Fill the radiator with coolant until its full. Let the truck heat up to 203* (or less if you have a different thermostat) so the thermostat will open. When it does it will suck all the coolant down. Refill with 50/50 mix until the radiator is full. Check to make sure there's heat in the cab. Once the radiator is full and its mostly done bubbling, remove the spill proof funnel and put the radiator cap on. Check for leaks at all the hoses and drain plugs. Go for a short drive to circulate and mix the coolant. When you get back use the antifreeze tester check the freeze and boil over protection. If you were able to drain the drivers side block you should be pretty close to 50/50. Mine was a little low because I didn't drain the drivers side of the block. I ended up draining 2 quarts out of the radiator and putting 2 quarts of straight concentrate coolant in. Went for another drive and retested my freeze protection and it was at -34* which is a 50/50 mix.

Check the coolant overflow and fill it accordingly with 50/50.

That's it you're done! If I missed anything or anyone has a better procedure please post it up.

Heater core hoses on the water pump
4f8f06a47c88677e8e34287254ffa479.jpg

Radiator petcock
bf56b78c7418ad12c6ba7159b8073322.jpg

Passengers side block drain
c02508fb28288be2d1753ad596559407.jpg

View of the passengers side block drain plug from the wheel well
042024b7f072df452a59ae4cdc277ff2.jpg

Best view I can get of the driver's side block drain
5fc81173191cf49d3bbc6c20fa2cb5df.jpg

Removing the thermostat gasket temporarily
bb265460d4f7dfec2274b90e9e237fa2.jpg
 
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R.L.K.

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R.L.K.

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So like... What about 3rd gen? :anitoof:

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I have a 2014 Ram and my coolant looks just like yours ....mine should have definitely had the Mopar OAT Purple stuff [emoji106][emoji106][emoji44]

For 3rd gen , all you have to do is remove the T stat , couple a garden hose to the heater core out line , remove the radiator cap and turn the hose on Full Blast till it's clean and full of chlorine [emoji23][emoji23][emoji16][emoji106]
Ha ha , just kidding [emoji106]

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R.L.K.

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Great post Hemi395 !!

Below is a coolant flush video from Chris Fix , not a hemi but the steps are basically the same as yours .

Hope this helps ...




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S0CAL

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@Hemi395 nice job! Thanks for the detailed post. Very informative.
Glad you insisted on the distilled water. Haynes manual has you putting a garden hose in the top of the radiator to flush!
 
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Hemi395

Hemi395

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Glad you insisted on the distilled water. Haynes manual has you putting a garden hose in the top of the radiator to flush!
I'll be honest, in my small block chevy days I used to use the garden hose to flush it. But those had iron heads and mostly iron components. With all the aluminum parts on the modern Hemi distilled is the safe way to go

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S0CAL

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Doing this (HOAT for me) this weekend. Will let you know if I can get to the driver side drain plug. Doing this in conjunction with eFan and 180 T-stat.
 
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Hemi395

Hemi395

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Doing this (HOAT for me) this weekend. Will let you know if I can get to the driver side drain plug. Doing this in conjunction with eFan and 180 T-stat.
Awesome thanks. I'd love to see how its done.
 

Jwithing

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Well, looks like it's warming up, so time for me to flush my hoat/oat/windshield wiper fluid mix lol. Thanks for the write-up. I'm expecting sludge, any recommendations for anything additional to flush other than distilled water?
 
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Hemi395

Hemi395

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Well, looks like it's warming up, so time for me to flush my hoat/oat/windshield wiper fluid mix lol. Thanks for the write-up. I'm expecting sludge, any recommendations for anything additional to flush other than distilled water?
Prestone makes a coolant flush that you could add to the water when you flush it. The only issue is you have to make sure you get ALL of it out which could take awhile...

Windshield washer fluid??
 

Jwithing

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Prestone makes a coolant flush that you could add to the water when you flush it. The only issue is you have to make sure you get ALL of it out which could take awhile...

Windshield washer fluid??
Meh... I may pass on it then since the drivers side drain plug is difficult.

Yes, I'm a ******* and wasn't paying attention when I went to put more washer fluid in lol.
 

Jwithing

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Another question... My driveway has a good slope. Any issues with not being level? Would it be advantageous to orient the truck in a certain way on my slope?
 
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Hemi395

Hemi395

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Meh... I may pass on it then since the drivers side drain plug is difficult.

Yes, I'm a ******* and wasn't paying attention when I went to put more washer fluid in lol.
Oh man I ALMOST did that a few years ago. Like I had the bottle tipped ready to pour and I realized last second that it was the coolant reservoir and not the washer tank.

@S0CAL possibly is doing a flush this weekend and he's going to check out the driver's drain plug...
 
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Hemi395

Hemi395

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Another question... My driveway has a good slope. Any issues with not being level? Would it be advantageous to orient the truck in a certain way on my slope?
It could make the intial bleeding of air a lot easier if the front of the truck is pointed up. But it really should be level when filling it up.
 

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