Coolant Flush

[Iggy913]

I'm sure most of you guys know how to flush and fill your own cooling system, it's really a simple procedure and not much different than on a normal vehicle, just a lot more fluid.

On my 923A2 even though the coolant looked bright green and relatively new I figured I would empty it out, run a hose through the various areas to see what came out, and refill it. That way I would know exactly when the coolant was changed last for the purpose of record keeping.

I drained the coolant through a combination of opening the valve on the bottom of the radiator and pulling the silicon hose off the joint between the transmission cooler and lower radiator hose. While at first I got bright green coolant as it got closer to being empty the color started to change from green, to a brownish green, to almost exclusively mud like. I stuck my garden hose in the overflow/fill tank and allowed it to run for almost five minutes before the water came out clean finally! I also stuck it in the "out" of the transmission cooler and got still more "mud".

It was pretty surprising really since the coolant looked so good. I did notice the transmission ran about 20-30 degrees cooler than the engine while driving around town and previously the motor and transmission would be nearly the same. The motor itself seemed to run a good 10-20 degrees cooler as well! So, unless you guys have done this procedure yourself I would highly reccomend doing it, you may be surprised like I was.

 

[Scar59]

What coolant brand did you replace it with? Spoke with a Cummins rep and he advises strongly to use diesel engine approved coolent, normally orange in color.
JC

 

[emr]

Both my deuces and cckw 352 when I had them I pulled the rads and flushed like crazy, had em boiled... That is the best of the best , But like you said flush her like crazy before something goes wrong !! The 925 is only getting the flush like you did because the rad is just so much bigger, and I hope only being an 1982 its good enough, if I get a ton of muddy water I will pull it though///,

 

[Iggy913]

My truck was a rebuild in 2012 and the radiator looked new, found out it was just a nice paint job on an older unit when I pulled the hose connections loose, you could see several coats of CARC over the rebuild cycles the truck has seen.

As far as what coolant I ran I plan on just using regular Prestone. I'm not sure what a "diesel specific" coolant would entail over any commercially available product. I actually didn't put any coolant back in the truck yet, it's not going to be anywhere near freezing around my area for at least another month or two. I'm going to run the water through it for a few days and see what it looks like when I drain it. I may take the radiator out if the water in it now isn't clean and have it boiled, if I end up doing that I'll probably take the transmission cooler and the fill tank out and have the three of them clean, you have to figure if there was sludge in any one of them it's in them all.

 

[Jakelc15]

A coolant filter is a cheap insurance also. I flushed my radiator and it also had a lot of mud in it.
I installed my coolant filter on my heater lines. I replace it once a year, when it starts to get cold outside, so my heat works at its best.
Wix coolant base 24019
Filter 24070 (no additive)
24071 24072 24073 24074 24075

 

[juanprado]

I also found lots of nastys in the heater core when I installed my coolant filter and flushed the lines. Ditto on the reservoir. I also found allot in the bottom of the radiator.

Hd "fleet" diesel antifreeze will say it on the bottle but if you install a coolant filter with the dca it will time release to keep the correct balance.

http://www.napaonline.com/Catalog/C...Cooling-System-1-GAL/_/R-FCRFCA053_0410678467

Make sure NOT to use red/orange dexcool for gm vehicles as it does not mix well with regular green formula and can turn to a jello like gel.
All hd fleet antifreeze I have seen is green, not sure if there is newer stuff out there?

You can look at my build here on ss "Major Zippidy" as I just posted recently some pics of my coolant filter install

 

[Scar59]

Juan,
Good info, the fleet diesel coolant I used was 50/50 pre-mix, orange tint in color. I'll have to get a jug out to see the manufacture, it wasn't a name brand. I'll get back.
JC

 

[thegreydog]

I just did mine today. I poured 5 gallons of Fleet and it was a bright magenta, even the Napa cool stuff matched it.

 

[jw4x4]

These engines are made with cylinder sleeves and highly recommend fleet coolant with SCA's (Supplemental Coolant Additives). The regular green stuff will work fine as coolant, but could possibly lead to corrosion issues farther down the road. When I replaced my oil cooler, there was regular green coolant in the system. I may or may not have contained additives. After flushing, I refilled the system with fleet coolant from Truck Pro.

 

[gimpyrobb]

Make sure you guys test the sca level. Too much can be as harmful as too little. I think its as easy as litmus paper tests. I am sure if you ask the "parts guy" he will be able to lead you to the test kits.

 

[jw4x4]

Use either the additives with regular coolant, or fleet coolant which already has additives, but not both. Also be aware if you have a coolant filter, it may also contain time release additives. Too much or too little is a bad thing. Gimpy is right on with recommending the test strips.

 

[Csm Davis]

Okay I can say that with the exception of a handful of y'all I have let the fluids out of more of these trucks than you have ever touched, that said every truck out there should flush and run a filter.

 

[Tow4]

You can also use an ELC coolant that doesn't need the SCA's. I use Rotella ELC coolant in all my diesel engines.