Coolant flush

[Usnavy700]

I have a 2015 ram 2500 had with the hemi 6.4l
My question is last winter I was have heat issues. I live in northern Minnesota. Had the heater core flushed. Worked well for a bit. Summer came and went and it’s cold again. Surprise!!!! Heat issues again. I have read several threads and talk to a few people knowledgeable on rams. Should I flush just the heater core again? Flush the whole cooling system? Replace the water pump? Or but the bullet and switch out the heater core? One guy recommended using the works toilet bowl wasn’t but flushing it out really well after 10 minutes. I know there is a chance of springing a leak if I do that. I’m kinda leaning towards flushing it again with radiator flush and doing that multiple times over time. It has 136,000 miles. I’m also partially tempted in adding radiator flush into the red out and running it for a while and flush the entire system. Thoughts?

 

[indept]

First are your heater hoses both hot? If so then it's most likely blend doors. If not, then do a total flush then fill with OEM coolant. Water pump & thermostat are optional but a good idea depending on your mileage. Check all of the other hoses too, this is the best time to replace them.
I like spending your money.

 

[mrack]

Flush it out. Cheap and easy and by far the most likely cause of your problem. Not uncommon at all to have to flush it every fall

 

[GTyankee]

If it was my vehicle ....

I would disconnect the 2 hoses that pass through the firewall & go to the heater core in the cab.
Use house water, usually a house has 50 pounds of pressure, use about 1/4 of that, about 11 pounds of pressure.
Run water into one hose & out the other, then reverse hoses.
Some ppl use a cleaner, like CLR & let it sit in the heater core for about 20 minutes, flush it out, run the house water again to flush it out.

If you still want to flush the Engine, grab enough hose to make a loop that excludes the heater core inside of the cab.
Maybe 2 or 3 foot of hose ought to do it.
Run the engine, until you are satisfied.

When you are satisfied, remove the short loop of hose & hang it in the garage for the next time it is needed.
Drain as much of the house water as you can. Displace it with either Distilled or Purified Water.
Distilled Water can be purchased for about $1.25 a gallon

Then Rams 2013 & newer use OAT antifreeze, 50/50 mix
There may still be a sticker under the hood that confirms that.

I may have not included every step, but someone will fill the rest in

 

[Jeepwalker]

Like said above, make sure it's not something else. Like blend doors, or a bad head gasket. If it seems to be the h/c, I've flushed heater cores using full house 50 psi pressure lol! Reverse-flush of course. Yeah, a lot of crud came out (it was a Jeep, not a Ram). Sometimes like you experienced before, it can make a major improvement.

You could get some CLR at Menards and fill it and let it soak a good while. But I have an old story where I once had a car years ago where I used a variety of very aggressive chemicals including straight lye. I 'cooked' that heater core probably 5 times thinking I could get it unclogged. The heater core would get so HOT with some chemicals, you couldn't touch it. And I let it soak overnight with like CLR or whaterver I did at that juncture. I wasted a lot of time on it. Never really improved the heat a whole lot. Got 'some' but not much.

Eventually on that car (fortunately the heater core was very easy to get in/out), I bought a new GM heater core for like $120 and I had instant heat ...to the extent I could heat a house! Moral of the story is, sometimes you just can't get those fine passages unclogged if a heater core gets really limed up, and it can be a waste of time to unclog. But it doesn't hurt to try. But if it doesn't produce results, you might have to buy a new one ...and go through the work to replace.

I'd probably flush it with straight water and disconnect the lower hose and let all and any crap in your system 'RUSH OUT' taking any debris with it. And heed the above suggestions of using distilled water & the right coolant for the final fill (using the right bleed process too). Although, i've used long-life green coolant in my Jeep 4.7 for 10 yrs ...and that's supposed to use special coolant. Haven't had any problems at all. But I do exchange it a little more often.