M923a2 Coolant System Drain and Flush:

[87cr250r]

A modern extended life coolant with nitrites is best. A conventional coolant with nitrites is second best.

Distilled water doesn't do anything so there is no reason to flush with it. IF you think your system is corroded use phosphoric or sulfamic acid to clean it, then flush with whatever water is available, then fill with your coolant mixture.

Utility grade water needs to not be corrosive to the pipes that transport it so it usually meets all of the requirements to be used as engine coolant. I would only buy distilled water if you're on a well. Your utility should publish regular water quality reports that you can compare to your engine manufacturer's requirements.

 

[Tacitus]

A modern extended life coolant with nitrites is best. A conventional coolant with nitrites is second best.

Distilled water doesn't do anything so there is no reason to flush with it. IF you think your system is corroded use phosphoric or sulfamic acid to clean it, then flush with whatever water is available, then fill with your coolant mixture.

Utility grade water needs to not be corrosive to the pipes that transport it so it usually meets all of the requirements to be used as engine coolant. I would only buy distilled water if you're on a well. Your utility should publish regular water quality reports that you can compare to your engine manufacturer's requirements.

OK thank you

 

[Defcon-1]

Coolant drain and flush is going really well so far, almost done. On the initial drain, it was very cloudy so instead of doing just distilled water I used garden-hose (city-provided utility) water. I flushed the system 5+ times, filling then running to temp (also taking on the road), and then dumping. I didn't even know about the left-side radiator drain port bc the TM only mentions the petcock on the right-side of radiator but there is a plug on the left side, when I removed that a lot more crud came out. I also at one time simultaneously ran the engine while it was draining and adding fresh water at the top (had a helper in the Cab to monitor temps) and then I started taking off heater hoses and turning valves open to make sure all the water was being ejected out. Having the engine running while adding water the same time as draining here and there really helped clear it up. I also made valves for both sides of the radiator so I could rapidly dump the water out, the petcock is too slow lol. I'm on my last drain and flush now (using distilled water this time), and then going to add distilled water / concentrate on the final fill-up. On the last flush when I opened up the after-cooler valve (while filling) when water started to come out it legit looked like drinkable fountain water, so I'm getting there.

Note: I did want to buy 45' npt fittings to angle it away from the glad-hands, but they were all out in-store so I went with a straight section, also thought I had hose in the garage to connect to but I didn't, oh well maybe next time lol. Also going to add an in-line coolant-filter on the heater hoses, have that on order but can add later since I can isolate those hoses from the rest of the system via the block valves.

 

[87cr250r]

Is there corrosion in your cooling system? Coolants can't protect corroded surfaces from further corrosion. Water flushing doesn't really do anything. If your system is oil contaminated you need to do a detergent wash. If it's corroded you need to do an acid wash. If it's oil contaminated and corroded you'll need to do both but you must start with the detergent wash.

 

[Defcon-1]

Is there corrosion in your cooling system? Coolants can't protect corroded surfaces from further corrosion. Water flushing doesn't really do anything. If your system is oil contaminated you need to do a detergent wash. If it's corroded you need to do an acid wash. If it's oil contaminated and corroded you'll need to do both but you must start with the detergent wash.

That's a negative on the oil contamination, no presence or evidence of oil in any of the drains. Can you further explain what would constitute as corrosion? On the first couple of drains the water was coming out murky, but not like any chunks or flakes of rust, very small and very fine particles I would say. Over the 8 fill-and-drains I did, I took (x4) samples throughout the process, I still have them in water jugs and will post up soon, but the last 2 samples (#6 and #8 were pretty clear/clean. After sitting for a few hours, the "sediment" from all those samples floated to the bottom, with #8 looking like drinkable water lol. Additionally, just curious on how would you stop the cast-iron block from rusting even if you did the acid wash? Anything to slow down or inhibit corrosion or is it just naturally a part of the system aging?

 

[WillWagner]

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.

Nope on the pink. Fleetguard sca was blue. Another "opinion". Look into Fleetguard antifreeze, the blue stuff. It is conventional but will mix with ELC types. And, yes, STAY AWAY from the red, orange extended life stuff, old engines have pieces internally that the ELC will attack and you end up with issues. Any conventional coolant that is low silicate will be fine with or w/o SCA, that can be added. If regular non low silicate coolant is used, you will have water pump leaking issues.

 

[87cr250r]

Only one Fleetguard coolant is "conventional"

https://cms.fleetguard.com/en_NA/literature/which-fleetguard-coolant-product-right-you/lt36237

The rest are OAT long life coolants.

Defcon, corrosion is any rust on the surface of the cooling passages. If the block is clean the corrosion inhibitors in the coolant will keep it that way. On well treated engines I have replaced timed out components such as water pumps that look like they just came out of the box.

 

[Defcon-1]

Defcon, corrosion is any rust on the surface of the cooling passages. If the block is clean the corrosion inhibitors in the coolant will keep it that way. On well treated engines I have replaced timed out components such as water pumps that look like they just came out of the box.

Thanks for the info, I'm going to have to continue to monitor the system over the winter time. The water coming out of the block was super clean after the drain and flushes, I didn't use any acid and thought the corrosion inhibitors in the concentrate would work. The first drain the water wasn't transparent, that was (most likely) due to no maintenance record on the truck done pre-August 2023 (when I bought it) so that coolant could've been 30 years old at that point lol. I lost a hose behind the water-pump (the one that goes 90' off of the block behind the alternator) so I wasn't planning on doing the coolant system work until spring when it warmed up, but kind of got forced into doing it way early with a very narrow window to get the block-heater in and antifreeze up to par before we have sub-freezing weather (which was legit the day after I finished working on it). I am going to install a coolant filter (WIX 24763 / 24070) so I'm hoping that will assist with the coolant condition, but I totally see where I possibly missed the mark on doing the acid wash to make sure the block was in good shape (even though I had clear running water after 8 drains/fills/run-ups to 185'). For the acid wash you mentioned, what ratio should I be looking to do (in the future)? Going to get pix of the samples I took throughout the process soon, it is a night/day difference from the original inherited condition I bought the truck in, but I can see now what you're saying that it will slowly degrade over time if the block isn't treated, hopefully the filter will help out with this lol. At least know I have the correct coolant-type in there with SCA's and correct antifreeze ratio, even though I might have to do it all over again in Spring to get the block clean lol. I'll have to take another sample in the next few months to see how it compares with the current system sample, I am going to keep them for continued monitoring.

 

[Nutman]

I run a lot of farm equipment, we always drain the coolant, fill with distilled water then run for 20 min. Drain and repeat until there is no color when you drain the water. It usually takes 2-3 times with distilled water. I personally run Mobil delvac coolant or John Deere coolguard 2. Cat ELC is probably made by Mobil just like their oil is. The Mobil delvac coolant has an 8 year 8000hr service life with electrolysis preventative additives. I personally only run pre diluted coolants to help reduce the chance of making a mistake.

 

[Nutman]

I run a lot of farm equipment, we always drain the coolant, fill with distilled water then run for 20 min. Drain and repeat until there is no color when you drain the water. It usually takes 2-3 times with distilled water. I personally run Mobil delvac coolant or John Deere coolguard 2. Cat ELC is probably made by Mobil just like their oil is. The Mobil delvac coolant has an 8 year 8000hr service life with electrolysis preventative additives. I personally only run pre diluted coolants to help reduce the chance of making a mistake.

Also don’t forget to burp your system, an air pocket can cause you to overheat and other problems.

 

[Defcon-1]

Also don’t forget to burp your system, an air pocket can cause you to overheat and other problems.

Yes Sir I was able to burb it and then added more coolant/anti-freeze to get it to the correct (final) level. Running at 185' now steadily.

 

[Defcon-1]

This is all just informational, the first "drain" was a total loss of coolant because I had to remove the lower hard-pipe section where the radiator connects to and where it goes into the transmission oil cooler, that was for changing out that leaking hose behind the alternator, so I wasn't able to recover any fluid from that first dump. However, I did a total of 8 drain and flushes on the truck, each time running to temp, then taking the truck out for a spin to get the thermostat to open, then dumping the fluid and doing the process over again. I measured the water going in and coming out, each of these samples were taken at gallon #4 (which was the 1/2 way point since I could only add about 8-9 gallons each time due to unable to FULLY drain the block, aka, some water I could not remove from the engine even with that lower line pulled out). There is a night/day difference between samples 2, 4, 6, and sample 8 was the (last) distilled water fill-and-drain. Then fully drained, added the concentrate and remaining distilled-water on a final fill up. Hoping that adding the coolant filter will assist along the way keeping the system clean. Going from "not being able to see the bottom of the coolant overflow reservoir" to "clear lake water" I'm sure will make a difference. I'm going to order test strips for the SCA levels too.

 

[87cr250r]

That's nasty. I would suggest doing a proper acid flush when you can. The cloudiness of the coolant doesn't affect it's performance. Coolant corrosion inhibitors are film forming type and can't form films under rust.

Remember that SCA levels are minimums. It's not possible for them to be too high. The minimum is usually 1500ppm. I strongly recommend an initial dose of 3000ppm.

 

[Defcon-1]

That's nasty. I would suggest doing a proper acid flush when you can. The cloudiness of the coolant doesn't affect it's performance. Coolant corrosion inhibitors are film forming type and can't form films under rust.

Remember that SCA levels are minimums. It's not possible for them to be too high. The minimum is usually 1500ppm. I strongly recommend an initial dose of 3000ppm.

The concentrate I bought was SCA pre-charged, but would like to monitor it as you mentioned. Is there an additive of just SCA I could add if I wanted to increase the PPM? Or do I have to drain some coolant out and mix the concentrate at a higher ratio? Also, what product would you recommend to test the SCA levels?

 

[87cr250r]

SCA is the concentrate. It stands for Supplemental Coolant Additive.

Caterpillar sells it, they simply call it SCA. Nalcool 2000 is another brand. For smaller quantities (<5gal) Pencool 2000 is probably easiest to find.

 

[Defcon-1]

Nope on the pink. Fleetguard sca was blue. Another "opinion". Look into Fleetguard antifreeze, the blue stuff. It is conventional but will mix with ELC types. And, yes, STAY AWAY from the red, orange extended life stuff, old engines have pieces internally that the ELC will attack and you end up with issues. Any conventional coolant that is low silicate will be fine with or w/o SCA, that can be added. If regular non low silicate coolant is used, you will have water pump leaking issues.

The coolant concentrate I bought from Napa (SCA pre-charged) was blue, or, it's a weird kind of purple lol.

 

[Defcon-1]

SCA is the concentrate. It stands for Supplemental Coolant Additive.

Caterpillar sells it, they simply call it SCA. Nalcool 2000 is another brand. For smaller quantities (<5gal) Pencool 2000 is probably easiest to find.

Yes Sir sounds good. The coolant-concentrate I bought from Napa is SCA pre-charged, but not sure how to test I have the correct levels? Could I also just use a SCA charged filter to maintain the levels, (post coolant-filter install), or should I just add some of the SCA liquid after so many miles/hours?

 

[87cr250r]

Various companies make coolant test strips. Fleetguard comes to mind.

Yes, you are supposed to add additional SCA every 300 hours and replace the coolant every 3000 hours or 3 years. Changing coolant filters replaces periodic dosing as the filters have additional SCA in them.

 

[WillWagner]

It is wise to get test strips and check concentration. Over charging causes issues just like non low silicate. Too much SCA will cause w/p seals to leak and coat liners with a thick coating that takes heat transfer away from the liner. Make sure the strips are compatable with the coolant you are using.

 

[Defcon-1]

Make sure the strips are compatible with the coolant you are using.

Uh oh, now I'm lost again lol. Different brands of coolant require different types of test strips for SCA levels?