M923a2 Coolant System Drain and Flush:

[87cr250r]

If you don't know the history of your coolant then you must change it. If the system is in good condition, drain it, fill it with fresh water, drain it, and fill it with new coolant of your choice. Use the OEM coolant if you have any concerns about compatibility. Otherwise you'll need to do a little research to pick what is right.

 

[Defcon-1]

I'm not gonna lie it's kinda discouraging seeing all this potential for major problems with all the different coolants.

Just got the block heater in a few days ago, (super easy, it was cake), but now have to do a fill-and-flush with distilled water. Then... going to research more on the best fluid to use as a final-refill, as it is "clear as mud" so to speak on what setup is ideal. Probably going the route of "1 gallon of distilled water to 1 gallon of anti-freeze concentrate" until it's full, then add SCA bottle at the end, then pray lol.

 

[DampLemonade]

Just got the block heater in a few days ago, (super easy, it was cake), but now have to do a fill-and-flush with distilled water. Then... going to research more on the best fluid to use as a final-refill, as it is "clear as mud" so to speak on what setup is ideal. Probably going the route of "1 gallon of distilled water to 1 gallon of anti-freeze concentrate" until it's full, then add SCA bottle at the end, then pray lol.

let me know what brand & type of coolant you end up using. I've got some contacts in heavy diesel repair shops and I'll respond in this thread if they have anything of substance to say.

The heater install itself seems to be the easiest part by a landslide lol

 

[DampLemonade]

If you don't know the history of your coolant then you must change it. If the system is in good condition, drain it, fill it with fresh water, drain it, and fill it with new coolant of your choice. Use the OEM coolant if you have any concerns about compatibility. Otherwise you'll need to do a little research to pick what is right.

I know the TM calls for 50/50 ethylene glycol to water, but every major parts store only seems to carry the Extended Life Coolants. Was that link that Jbulach posted good to use?

 

[87cr250r]

The pre-diluted extended life coolants ARE 50/50 ethylene glycol and water with corrosion inhibitor.

You MUST not run any coolant without corrosion inhibitors.

If you WANT conventional coolant hit up your local Caterpillar dealer and ask for Cat DEAC coolant. It comes pre-diluted 50/50 and has SCA for engines that require it.

 

[Jbulach]

I know the TM calls for 50/50 ethylene glycol to water… Was that link that Jbulach posted good to use?

This is 100% ethylene glycol, so you need to dilute it with distilled water, and I’m about 90% sure it is IAT due to it meeting all these pro OAT specs… “Hot Surface Aluminum protection requirements of ASTM test D4340 and Cummins Heavy Duty Low Silicate requirements, and is designed to meet the requirements of TMC RP-330, GM1825M, GM1899M, Chrysler MS7170, and Ford ESEM97B44A”.

 

[Jbulach]

Miles has an online chat they could probably confirm IAT, OAT, or HOAT. No luck for me trying to chat on my phone…

 

[Jbulach]

https://www.napaonline.com/en/p/ZRXZXPCRU1?cid=paidsearch_shopping_dcoe_google&store=27554&campaign=GSC-Chemicals&campaign_id=6478876245&adgroup_id=115972171828&adtype=pla&gclsrc=aw.ds&gad_source=1

Thinking this would be good to go as well…

 

[Jbulach]

Zerex Antifreeze Coolant, 1 gal., RTU ZXPCRU1 | Zoro

Order Zerex Antifreeze Coolant, 1 gal., RTU, ZXPCRU1 at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for an account.

www.zoro.com

This Zerex does specify IAT

“Application
Offers protection against liner pitting and hard-water scale deposits in heavy-duty diesel engines. Proprietary inhibitor chemistry helps protect all cooling system metals, including aluminum, against corrosion. Universal coolant can also be used in gasoline engines and light-duty vehicles. Compatible with major American ethylene glycol-based coolant brands. IAT formula. 150,000 mi/3000 hr/3 yr”

 

[DampLemonade]

Zerex Antifreeze Coolant, 1 gal., RTU ZXPCRU1 | Zoro

Order Zerex Antifreeze Coolant, 1 gal., RTU, ZXPCRU1 at Zoro.com. Great prices & free shipping on orders over $50 when you sign in or sign up for an account.

www.zoro.com

This Zerex does specify IAT

“Application
Offers protection against liner pitting and hard-water scale deposits in heavy-duty diesel engines. Proprietary inhibitor chemistry helps protect all cooling system metals, including aluminum, against corrosion. Universal coolant can also be used in gasoline engines and light-duty vehicles. Compatible with major American ethylene glycol-based coolant brands. IAT formula. 150,000 mi/3000 hr/3 yr”

So from my understanding so far, looks like buying this and a dose of SCA should be good and safe?

 

[87cr250r]

If it's pre-charged or fully formulated you DO NOT need the additional dose of SCA on the initial fill. With that said, you cannot add too much SCA. You could literally run an engine on straight SCA without doing damage. Normally dosed, you DO need to add SCA every 300 hours and change the coolant every 3000.

If you can accept that the newer ELC coolants are superior and are the reason IAT coolants are so hard to find you can fill your system once and forget it for the next 10 years. I do suggest HOAT coolants for older diesel engines. Caterpillar ELC is a HOAT.

 

[Defcon-1]

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[Defcon-1]

So from my understanding so far, looks like buying this and a dose of SCA should be good and safe?

This look like it already has the SCA's added, bc it talks about liner pitting, which through some reading, is the 8.3's downfall because it is more susceptible to cavitation (via the coolant barrier) because the cylinders have removable liners instead of being solid-bored.



There is also a "Heavy Duty EL" version of this fluid, and it looks like that it *does not* have the additives in there because it talks about using a blank filter (a coolant filter without SCA additive) and then adding the "Extender" to it per 50 quarts.

 

[Defcon-1]

I do suggest HOAT coolants for older diesel engines. Caterpillar ELC is a HOAT.

What do you consider to be an older diesel engine? You mean older model like the NHC250 vs 6CTA8.3? Or older as in operational hours / total age in years?

 

[Defcon-1]

let me know what brand & type of coolant you end up using. I've got some contacts in heavy diesel repair shops and I'll respond in this thread if they have anything of substance to say.

The heater install itself seems to be the easiest part by a landslide lol

This is the route I'm going, choosing this over the Zerex 50/50 mix because when using the concentrate it will be cheaper buying 1-gallon distilled waters and adding it to the system. 48 qts = 12 gallons, so buying 6 of these (actually 8 to have extra) and then going to add 6 gallons of distilled water. (I'll add a gallon at a time going back and forth between concentrate and distilled water to make sure it's even).

Therefore it's essentially 1/2 price than buying pre-diluted gallons (would need 12 gallons of the Zerex compared to 6 of these Napa, since they are both roughly $12). I'm not sure if these are "fake on sale" being listed at $22.99 and now being $12.99 each, but I think it's a reasonable route to go.

 

[87cr250r]

I would consider anything pre-aluminum radiator an older diesel. Nitrites can cause problems with brazed aluminum radiators.

Nitrited or Nitrite-Free Coolants? | Chevron Lubricants (US)

www.chevronlubricants.com

 

[DampLemonade]

I would consider anything pre-aluminum radiator an older diesel. Nitrites can cause problems with brazed aluminum radiators.

we don't have brazed aluminum radiators on the 939 right? looks like all the coolants mentioned in this thread have nitrites, I just wanna be safe.

I am a big noob with coolants so I really appreciate all of your input

 

[juanprado]

Correct, we have old school radiators no aluminum

 

[DampLemonade]

This is the route I'm going, choosing this over the Zerex 50/50 mix

I just made the exact same purchase lol. 8 gallons of concentrate for $100 isn't bad at all.

Thanks for the help everyone!

 

[Tacitus]

I haven’t posted much due to work, just retired so now have time to work on my M923. Completely new to owning & maintaining this truck. It is all stock as far as I know. Plate on the engine for emissions is stamped 1983, I assume that’s build date? I’m a little OCD about truck maintenance so I plan on using distilled water to flush. I don’t know if this is aluminum radiator. What exactly do I need to use for coolant and additive? I want the best for this truck, thanks in advance for your time and assistance.