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Whats the best way to do a coolant system flush on the 6.5?

Jaryd

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Im getting ready to install the Brass Works heater core that some of the forum members here donated to me and was coated by Twistedsteel Performance. I want to flush the system real good and do it right before I put the brass heater core in.

I thought about unhooking the radiator hoses and making some PVC adapters that I’ll hose clamp to the radiator hose and I can hook my hose pipe to the other end and use the pressure from the hose pipe to push everything out. I would do the block and then the radiator. There’s probably a little oil in the coolant to because I had to use a empty Rottella jug to fill up to get me home the night it started leaking. I’ve heard powdered dish detergent will work good for getting the oil flushed out but have never tried it?

Ive been looking at doing a bypass coolant filter that goes in the heater core hose. I feel like this would be my best way to keep everything good and clean but is it something that is really needed if you flush everything real good? I know that they make a see through tube with wire mesh in it that goes in the top radiator hose that I also thought about adding if I didn’t do the coolant bypass filter.

I want to do this right so I don’t mess up the new heater core and so everything will last like it should. What have y’all done to flush the coolant system in these trucks and what do y’all think about adding a bypass filter or the see through filter that goes in the top radiator hose?
 

MrMarty51

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I dont know how well those flush systems work, the ones that goes into the heater hose. I guess if the water is run long enough it should at least get the main of the old coolant removed.
I`ve always been skeptical about instilling detergents into the cooling system. I just dont know how well a person would be able to get it all flushed out, and I am sure that detergent bubbles would not have musch cooling capabilities.
I`m with AK diesel driver on the acid part of the flush. I would think if citrus acid is not available then I am sure that apple cider vinegar would also work, even if it is diluted down some.
I would think that the acid would also remove oil and petroleum products from the cooling system too.
 

Jaryd

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If I really wanted to clean the block I'd use citric acid and let it set overnight then flush really well, should look like brand new cast iron when your done. I'd also use only distilled water with the antifreeze you put back in
straight citric acid or diluted? I’m assuming diluted but by how much? I’m guessing drain coolant system and put the acid in and run the truck to get it flowing? Im assuming it won’t hurt the aluminum or gaskets or the Perma Tex Ultra Black that I used on some of the surfaces when I put it back together a few years ago? Take the TStat out so it’ll circulate without much effort or leave the TStat in and run it for a couple minutes?

As you can tell I’ve never used citric acid but if it’ll clean it up really good and everything can handle it I’m not against using it.
 

ak diesel driver

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won't guarantee it won't hurt anything but a buddy of mine has used muratic acid without any issues and I'd think it would be much harsher. Citric acid should mainly remove rust, lemon juice, orange juice, etc will do the same thing. There's a product called Deox C that does an amazing job as well and I believe it's just citric acid. I believe the solution is in the 5-10% range
 

Will L.

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What Ive always done is turn heater on, pop the upper hose off at the radiator point, take out the tstat(s). Then just hold the garden hose in the upper hose and let everything puke out the top of the radiator. Let the water run until it’s all clear as back flush. Then feed it the correct direction down the radiator until it’s clear the other way- barely anything comes out but water but still some. Obviously back and forth doesn’t hurt anything. Then start the engine because the waterpump can drive it through the heater hoses better on some rigs. But since replacing yours, I would keep it turned off. Let the chemical clean the radiator and engine better, not the part your replacing. For systems that have zero rust or mineral build up this is enough.

Depending what exactly you have to clean out is what acid to use. Read all over internet and phosphoric acid is suggested for rust but most don’t know you HAVE to scrub the part to do any good. If you don’t physically remove it the crystalline will keep most of the rust against the iron. So DONT use it for engine flush.

Citric is good like mentioned above. Hydrochloric acid/ Muriatic acid can be used also, just takes less time and all can be bought at hardware stores. Just make
Sure you wear gloves, eye protection, and only add acid to water, never water to acid.

Prestone flush is really good also, just takes a bit more time. If you don't have anything like lime build up in radiator or have a bunch of rust come out on first water flush- I would just use the prestone. It is a blend that chemists came up with to do the best all around job.
If you are already in freezing weather, you need to get antifreeze back in when done in 1 day. Otherwise driving through a few days hot and cold cycles helps remove more crap.

My method, I would do water on flush mentioned above, drain that then refill with water. Drain out 1 gallon and add 1 gallon of muriatic acid (pool acid) that is listed as roughly 30% on label. Then just 10 minutes of driving hot works wonders. ALL methods have to get it hot even if you have to cardboard block radiator. Drain acid mix. Flush with just water and hot drive again. If after drive it comes out clean-good. If not repeat acid step. some folks drive 1/2 hour instead of 10 minutes- but i get panicky and rather spend more cash and effort doing it twice. One cycle of muriatic has solved 95% of systems for me. Only ones that are CRAZY bad ever needed more than one cycle.

When doing ANY of the acid treatments other than prestone, always after pure water flush (Cant flush too much water through), you take a whole box of baking soda and mix with water- then run it through the system in drive cycle, then flush with water one last time. This is important because if you don't neutralize the acid, and the antifreeze you use don’t mix, there can be a layer of acid that lives against part of radiator or something that will continue eating away. There are other things to neutralize, baking soda is just easier for me.

Some folks worry about flushing water being mineral water and only use distilled to flush with. I rather pump 100+ gallons through and use house pressure to rinse, then I save the distilled for final fill up. Distilled even for flushing is better, but seriously flush over 100 gallons in my process. So if you mandate only distilled, purchase a pallet of jugs, or set up your distillery a couple days ahead.
 

Jaryd

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What Ive always done is turn heater on, pop the upper hose off at the radiator point, take out the tstat(s). Then just hold the garden hose in the upper hose and let everything puke out the top of the radiator. Let the water run until it’s all clear as back flush. Then feed it the correct direction down the radiator until it’s clear the other way- barely anything comes out but water but still some. Obviously back and forth doesn’t hurt anything. Then start the engine because the waterpump can drive it through the heater hoses better on some rigs. But since replacing yours, I would keep it turned off. Let the chemical clean the radiator and engine better, not the part your replacing. For systems that have zero rust or mineral build up this is enough.

Depending what exactly you have to clean out is what acid to use. Read all over internet and phosphoric acid is suggested for rust but most don’t know you HAVE to scrub the part to do any good. If you don’t physically remove it the crystalline will keep most of the rust against the iron. So DONT use it for engine flush.

Citric is good like mentioned above. Hydrochloric acid/ Muriatic acid can be used also, just takes less time and all can be bought at hardware stores. Just make
Sure you wear gloves, eye protection, and only add acid to water, never water to acid.

Prestone flush is really good also, just takes a bit more time. If you don't have anything like lime build up in radiator or have a bunch of rust come out on first water flush- I would just use the prestone. It is a blend that chemists came up with to do the best all around job.
If you are already in freezing weather, you need to get antifreeze back in when done in 1 day. Otherwise driving through a few days hot and cold cycles helps remove more crap.

My method, I would do water on flush mentioned above, drain that then refill with water. Drain out 1 gallon and add 1 gallon of muriatic acid (pool acid) that is listed as roughly 30% on label. Then just 10 minutes of driving hot works wonders. ALL methods have to get it hot even if you have to cardboard block radiator. Drain acid mix. Flush with just water and hot drive again. If after drive it comes out clean-good. If not repeat acid step. some folks drive 1/2 hour instead of 10 minutes- but i get panicky and rather spend more cash and effort doing it twice. One cycle of muriatic has solved 95% of systems for me. Only ones that are CRAZY bad ever needed more than one cycle.

When doing ANY of the acid treatments other than prestone, always after pure water flush (Cant flush too much water through), you take a whole box of baking soda and mix with water- then run it through the system in drive cycle, then flush with water one last time. This is important because if you don't neutralize the acid, and the antifreeze you use don’t mix, there can be a layer of acid that lives against part of radiator or something that will continue eating away. There are other things to neutralize, baking soda is just easier for me.

Some folks worry about flushing water being mineral water and only use distilled to flush with. I rather pump 100+ gallons through and use house pressure to rinse, then I save the distilled for final fill up. Distilled even for flushing is better, but seriously flush over 100 gallons in my process. So if you mandate only distilled, purchase a pallet of jugs, or set up your distillery a couple days ahead.

I don’t have a heater core in the truck right now. Been out for a few months. I just put a Pex ball valve in between the supply and return hoses and leave it in the on position so the water can circulate. I figured that I would do all the flushing with the ball valve in place and then install the new heater core before I filled with coolant. I’ll run some water through the new heater core before I install it just to flush it some but won’t do any kind of acid.

when I built my house I installed a couple hot water hose bibs outside beside the cold water hose bibs. I could flush and fill with with the hot water and already have a head start on getting the engine and flush water warm before I drive it.

I like the method that you said with the muriatic acid and then do the baking soda. Seems like the best way to get it good and clean and flushed out real good. I’ll hoping to be able to do this this weekend so I’ll read your post a couple more times before then.
 

Jaryd

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What are y’alls thoughts on a coolant bypass filter or the wire mesh filter?


The wire mesh filter. This is the first one that popped up on the search.


The coolant bypass filter. First one to pop up. I can build my own a lot cheaper than this.
 

Will L.

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Screen not worth the cost. What is it going to catch? Fine rust particles that could go through the 800um screen and I don’t see large material going through the system. If it had a magnet in it, maybe it would collect iron particles, maybe. It shouldn’t hurt anything other than a new point of failure, but low chance there.

On the filter- NO. Those coolant filters contain tablets that dissolve into the system adding nitrates and such. In a wet sleeve diesel thats good, but not in a 6.5. Those extra minerals are bad news. It is the exact opposite of using distilled water but times 100.

The filter is just a bypass system so any filtering it actually does is minimal. I’ve installed hundreds of them in fleets on semi trucks. Cut a bunch open and never anything of significance found inside.

Engine oil, fuel, tran, need filters. Even power steering benefits from filtering. But nothing in the cooling system really does imo.
 

Jaryd

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I agree on the mire mesh filter. To much money for what it is. Just wondering if y’all thought it would be worth it. Only thing I can see it catching is probably some gasket maker after doing head studs or a water pump change.

I figured between the two the bypass filter would be the best. I knew the bypass filter was filtering a little at a time but didn’t know if it was worth the investment. Didn’t know about it adding bad stuff to the mix. Im glad I asked.

I want to flush this thing and do it right before I install the brass heater core.
 

Jaryd

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Getting the sacrificial anode for the radiator/ heater core is a good idea worth spending nickels on.
Whats that

Just had time to look it up. I’m going to see if i can figure out what the drain plug threads are in my radiator. Hopefully I can find one that’ll thread in there. It’s the aluminum coil with plastic sides radiator so would it matter if the anode don’t screw against any type of metal. I see some with a way to ground it. If I cant find one with the ground wire wire attached I could solder a wire to the brass head and ground the wire if it needs it.
 
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ak diesel driver

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If you put the filter in with a ball valve to bypass then you could force the fluid through it occasionally. I don't know as I'd want it restricting the flow all the time
 

MrMarty51

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The drain cock on the 2000 K3500 is one of them plastic things that screws out a ways then with a pull it opens up full flow. Goofy thing but I think it is not pipe thread.
 

FellowTraveler

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Zink anodes are for salt water environment & cooling systems magnesium anodes are for vehicle cooling systems.

I suspect anodes will not do any good with nitrates or OATS type coolant.

This is another area waterless coolant will not flow current preventing electrolysis.
 
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Will L.

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Zink anodes are for salt water environment & cooling systems magnesium anodes are for vehicle cooling systems.

I suspect anodes will not do any good with nitrates or OATS type coolant.

This is another area waterless coolant will not flow current preventing electrolysis.
Unless it is a high mineral added system for wet sleeve diesels like the above shown coolant “filter”. Many of the minerals that have to be added to stop local point heating, some people still use and that makes it conducive. Imo a mistake to use those additives and the evans. But some engine warranties mandate the tablet filters, especially heavy equipment. If it were me using evans and a new truck requiring I would do the garden hose flush to wear out the tablet before it went on.

Evans is like 80-90% polypropylene glycol and no water. It in itself isn’t electrically conductive but can become so with additives. Thermally conductive and electrically rates are 2 different items, but never far off- one of wideman frantz law iirc.

It’s kinda like water: pure H2O does not conduct electricity- all the stuff floating in it does. Thats a part of how distilled water helps in cooling systems. Keep the Evans pure and keep your radiator and heater core electrically isolated and you have no problems.
 
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