M923a2 Coolant System Drain and Flush:

[Defcon-1]

Hello and Good Day Gents,

Just to preface this, I am in the TM (9-2320-272-24-1 section 3-150 “Coolant System Maintenance”) so I have the Technical portion of the process in-hand. However, I have a few questions regarding the coolant system and am requesting some advice / wisdom from those who have the experience, thank you. I want to install a block heater on my M923a2, so at the same time I thought it would be appropriate to drain and flush the entire coolant system, so my questions are regarding the coolant flush. The block heater install looks pretty straight forward, but the coolant flush there are some things I’m wondering about…

• What type (and I’m talking about brand-specific) of anti-freeze should I be using to meet the 16-quart requirement (per the lowest temp in my region at 0’ F)? This is my first diesel vehicle, so I’m not used to anything that has those protection elements in it, not really sure what to use as the anti-freezer additive.
  
  
• Is it appropriate to use something like Thermocure / Prestone Cooling System Cleaner to aid in the coolant flush? Is that worth doing because I see that those products only treat up to 3 gallons, they are kind of expensive so would I need to get enough to treat 11+ gallons worth for the entire coolant system?
  
  
• When I do the system flush with water, (fill and drain), can I just use garden-hose water or do I have to fill it up with distilled water each time? This is not to keep the water in the engine, I’m talking about specifically filling up the system, running it for a little bit, then immediately draining it out to get all the debris out. I know I have to fill it with distilled water to run it long-term, but wasn’t sure if adding regular water (temporarily) would harm anything?
  
  
• Down the road, let’s say I have to top off the coolant system. Is it ok to add Prestone 50/50? (Related to my inexperience with diesel engines)
  
  
• Are there any additives I should be including into the anti-freeze / distilled water (final) fill up? Anything to further help protect the coolant or engine? I read something on another thread about a SCA from Fleetguard? How much of that do I need? Again, this is related to my inexperience with diesel motors.
  
  
• Are there any plugs on the engine block that I need to remove to assist in draining the coolant? The TM only mentions the radiator drain valve and the aftercooler drain, shouldn’t there be a low-point drain on the engine block itself?

Any help or advice is appreciated, ty!

 

[thedmaxman]

Hello and Good Day Gents,

Just to preface this, I am in the TM (9-2320-272-24-1 section 3-150 “Coolant System Maintenance”) so I have the Technical portion of the process in-hand. However, I have a few questions regarding the coolant system and am requesting some advice / wisdom from those who have the experience, thank you. I want to install a block heater on my M923a2, so at the same time I thought it would be appropriate to drain and flush the entire coolant system, so my questions are regarding the coolant flush. The block heater install looks pretty straight forward, but the coolant flush there are some things I’m wondering about…

• What type (and I’m talking about brand-specific) of anti-freeze should I be using to meet the 16-quart requirement (per the lowest temp in my region at 0’ F)? This is my first diesel vehicle, so I’m not used to anything that has those protection elements in it, not really sure what to use as the anti-freezer additive.
  
  
• Is it appropriate to use something like Thermocure / Prestone Cooling System Cleaner to aid in the coolant flush? Is that worth doing because I see that those products only treat up to 3 gallons, they are kind of expensive so would I need to get enough to treat 11+ gallons worth for the entire coolant system?
  
  
• When I do the system flush with water, (fill and drain), can I just use garden-hose water or do I have to fill it up with distilled water each time? This is not to keep the water in the engine, I’m talking about specifically filling up the system, running it for a little bit, then immediately draining it out to get all the debris out. I know I have to fill it with distilled water to run it long-term, but wasn’t sure if adding regular water (temporarily) would harm anything?
  
  
• Down the road, let’s say I have to top off the coolant system. Is it ok to add Prestone 50/50? (Related to my inexperience with diesel engines)
  
  
• Are there any additives I should be including into the anti-freeze / distilled water (final) fill up? Anything to further help protect the coolant or engine? I read something on another thread about a SCA from Fleetguard? How much of that do I need? Again, this is related to my inexperience with diesel motors.
  
  
• Are there any plugs on the engine block that I need to remove to assist in draining the coolant? The TM only mentions the radiator drain valve and the aftercooler drain, shouldn’t there be a low-point drain on the engine block itself?

Any help or advice is appreciated, ty!

I'm working on the same thing now, and have similar questions.

 

[silverstate55]

I use distilled water only to flush…too many impurities in tap water. If there’s oil in your antifreeze then add some Cascade dish soap to clean it all out (and find/fix the problem), if you’ve got lots of rust & scale then flush with white vinegar.

Otherwise go to NAPA to get the green Low-Silicate coolant made for heavy duty diesels, you can add a small container of SCA (NAPA has them in small bottles). If you’re not using the truck to haul regularly heavy loads or for over-the-road long haul trucking you shouldn’t have much to worry about.

Get an extra jug or two to keep on hand for topping off.

When I did my 8.3 Cummins I followed the directions in the TM you mentioned, it seemed to work fine Over the past few years.

 

[Valor]

There is a block drain on the passenger side of the engine. You can take that out and use a hose to squirt water in and around the cylinders to clean out the block. Just let it drain out. Fill the radiator with hose water and let it run out and see what kind of gunk comes out. I used cascade with hose water mix to flush mine. Just mix it so it's soapy and doesn't have any sediment in the mix. I used fleet charge antifreeze to refill. My old coolant looked like muddy coffee! The block drain is circled in red in the pic.

 

[Defcon-1]

Otherwise go to NAPA to get the green Low-Silicate coolant made for heavy duty diesels, you can add a small container of SCA (NAPA has them in small bottles). If you’re not using the truck to haul regularly heavy loads or for over-the-road long haul trucking you shouldn’t have much to worry about.

Is the Green Low-Silicate Coolant already deluded? Or does it come in a concentrate and then you have to do the calculation per water ratio? I'm used to only adding Prestone 50/50 to all my vehicles for initial fill-up and top-off lol.

 

[Defcon-1]

There is a block drain on the passenger side of the engine. You can take that out and use a hose to squirt water in and around the cylinders to clean out the block. Just let it drain out. Fill the radiator with hose water and let it run out and see what kind of gunk comes out.

Excellent, ty so much. Did you run the engine when you filled it up with hose-water / dish-soap to get everything churned up? Or did you just do a fill-and-drain until it came out clean?

 

[silverstate55]

Is the Green Low-Silicate Coolant already deluded? Or does it come in a concentrate and then you have to do the calculation per water ratio? I'm used to only adding Prestone 50/50 to all my vehicles for initial fill-up and top-off lol.

I usually got it as a concentrate…. But if you pour half a jug into a clean 5-gallon bucket & mix an equal amount of distilled water into the half-jug, you now have 50/50 mix. Use a large funnel to pour concentrate back into jug. I keep used antifreeze jugs to store my mixed 50/50 antifreeze in, so it’s ready to go. Quick and easy.

 

[DeMilitarized]

@Elijah95 will tell you that running green coolant is a death sentence to your cooling system rather than running an extended life coolant. The green stuff will cause major cavitation issues with the liners and the block and will eat away the liners until they have holes in them. Running hose water for the flush is fine but you want to use distilled and make sure you have as much of that hose water out when you do your final coolant add and swap it for distilled. You will also want to check the rating of your mixed coolant with a cheap gauge from autozone or something to see the actual freezing capacity of the coolant.

 

[Jbulach]

Thats what SCA additives are supposed to be for, or buy precharged coolant, you can also get precharged filters that will help maintain your SCA levels. Just as many horror stories running ELC in these older engines. After reading both sides of the debate, I went with cheap green precharged coolant, and a non charged filter for the first season,
then switched to a charged filter the following year. Also, if your cooling system is full of the typical “mud” found in these trucks it will take many heat cycles or removal of the thermostat to flush most of it out. If I fid it over again I would have removed the thermostats, or flushed mine in the heat of the summer, so I could have got the thermostat to open quicker between flushes. Mine was so bad I flushed with tap water until I felt I had most of the crap out, then did a flush with straight distilled water to help dilute any remaining tap water, before adding my final mix. Also, the capacity of these systems are so big just start with a gallon of 100% concentrate then a gallon on distilled water then continue alternating until full. Then run through a heat cycle then test before topping off. Remember you wont get all of the straight water from the flush out.

 

[cbrTodd]

Jbulach is right. SCA additive at the right level added to the standard green coolant (and confirmed regularly with test strips or other means) will prevent liner cavitation. Unless you have changed your head gasket on your 6CTA out for the Dana graphite style, you have the Fel Pro kind with silicone coolant seals, and the ELC / organic acid style coolants will eat that away, regardless of what the label says. Use the orange or yellow coolants at your own peril on these older engines. Source - I went with Zerex G05 coolant after a flush, had a head gasket leak a year later, and confirmed the coolant seals were delaminating and partially gone. I had the fun of replacing a head gasket in my driveway.

 

[87cr250r]

Any coolant you buy at the auto parts store is going to be an organic acid type coolant. Conventional coolants are no longer sold at the consumer grade level.

If you do want a conventional coolant Caterpillar DEAC is still available. This coolant does require regular dosing of SCA.

If you want an extended life coolant and are concerned about liner cavitation, Cat ELC is a hybrid coolant with nitrites.

If you don't want to buy from Cat, Chevron ELC is a comparable hybrid coolant.

The flushing fluid is phosphoric acid. You can buy this at your local hardware store as concrete etcher if you want to save some money. Coolants cannot protect metal under rust so if you have corrosion in your cooling system you need to flush it with an acid.

 

[Defcon-1]

Any coolant you buy at the auto parts store is going to be an organic acid type coolant. Conventional coolants are no longer sold at the consumer grade level

- Is this the better option of the two? Organic-Acid over Conventional? I'm not sure what the standard would be.

If you do want a conventional coolant Caterpillar DEAC is still available. This coolant does require regular dosing of SCA.

- How regular are we talking? Annually or does it go per mileage / engine-hours?

Cat ELC is a hybrid coolant with nitrites.
If you don't want to buy from Cat, Chevron ELC is a comparable hybrid coolant.

- Do the ELC fluids already have the SCA's in them? I'm not sure about all this so am just double-checking to make sure I get the correct combination.

 

[Defcon-1]

Jbulach is right. SCA additive at the right level added to the standard green coolant (and confirmed regularly with test strips or other means) will prevent liner cavitation. Unless you have changed your head gasket on your 6CTA out for the Dana graphite style, you have the Fel Pro kind with silicone coolant seals, and the ELC / organic acid style coolants will eat that away, regardless of what the label says. Use the orange or yellow coolants at your own peril on these older engines. Source - I went with Zerex G05 coolant after a flush, had a head gasket leak a year later, and confirmed the coolant seals were delaminating and partially gone. I had the fun of replacing a head gasket in my driveway.

Definitely don't want to be doing any engine work because I messed up the coolant flush lol, no barn/pole-shed to work under lol. I never ever heard of the yellow/orange fluid before... definitely a newb to diesel engines that's for sure. Is that what you're running now? The green with SCA's added in?

 

[Defcon-1]

Thats what SCA additives are supposed to be for, or buy precharged coolant, you can also get precharged filters that will help maintain your SCA levels. Just as many horror stories running ELC in these older engines. After reading both sides of the debate, I went with cheap green precharged coolant, and a non charged filter for the first season, then switched to a charged filter the following year. Also, if your cooling system is full of the typical “mud” found in these trucks it will take many heat cycles or removal of the thermostat to flush most of it out. If I fid it over again I would have removed the thermostats, or flushed mine in the heat of the summer, so I could have got the thermostat to open quicker between flushes. Mine was so bad I flushed with tap water until I felt I had most of the crap out, then did a flush with straight distilled water to help dilute any remaining tap water, before adding my final mix. Also, the capacity of these systems are so big just start with a gallon of 100% concentrate then a gallon on distilled water then continue alternating until full. Then run through a heat cycle then test before topping off. Remember you wont get all of the straight water from the flush out.

This might seem like a dumb question, but, how do you have a coolant filter? Maybe I'm missing something in the engine bay lol.

 

[Jbulach]

Sorry, thought I read you where adding it as well as the block heater, I’ll see if I can dig up a link to a thread.

This is the coolant I used https://mileslubricants.com/product/show/miles_evercool_(multi_duty_green_antifreeze)_(5_gallon) maybe @87cr250r can confirm it’s old school, non-ELC conventional green? I’m shocked to hear parts stores no longer sell non-ELC.

 

[Jbulach]

See if this link works…


https://www.steelsoldiers.com/threads/adding-a-block-heater-and-coolant-filter-on-6cta-8-3.131589/

I posted pictures of my install on this thread, a little different than the OP’s install.

 

[87cr250r]

When you see this line: "formulated to be compatible with antifreeze/coolants of all major producers. " It can't be a conventional inorganic acid type coolant.

FYI, SCA has always been pink.

 

[87cr250r]

Dosing with SCA is supposed to be once every 300 hours if I remember correctly.

ELC coolants perform better provided the system is clean.

Not all ELC coolants protect against liner cavitation. Not all engines need protection. For example, Caterpillar requires a hybrid coolant with nitrites. John Deere forbids nitrites because they are corrosive to brazed aluminum radiators.

Do not add SCA to an ELC coolant.

If you are using a coolant filter make sure it is the correct one for your coolant. Don't use a filter with SCA with ELC.

Cat has a really good white paper on coolants. I'll have to dig it up when I have time.

 

[DampLemonade]

i'm also hopping in on this thread bc I plan to add a block heater to my NHC 250. I'm assuming these coolant concerns are the same across both the 14L and 8.3L?

I'm not gonna lie it's kinda discouraging seeing all this potential for major problems with all the different coolants. I had a bunch of Walmart brand prediluted semi-truck coolant in my shopping cart earlier but now I'm considering forgetting about the block heater, keeping the coolant thats in it now, and just building a small campfire under my oil pan this winter... I do not have a garage equipped to be pulling heads on a motor this size lol

 

[juanprado]

Adding a block heater to a nhc 250 is super easy. You can always capture and reuse the coolant with the drain cock if good.