Favorite Chemicals for Coolant Flush

I've done plenty of coolant flushes in mostly the automotive and powersports world, but usually I do it is as PM instead of a response to a problem.

My Kubota L305DT is getting warm when at PTO Operating speed and tends to stay up there until I throttle back and reduce the load. I've had a slight amount of coolant boil over and after inspecting the radiator, the cores look to be a bit scaled up and in need of a good cleaning. So my question is - who has used what and what do people recommended? I'm looking for a chemical additive (or different process than garden hose flush) to aid in getting the cooling system clean and operating efficiently again.


There's a bunch of different home remedies and off the shelf "mechanic in a bottle" solutions so lets here some opinions!


To cover the bases about the overheating, here's what I know about the situation:
-Screen and fins are clear
-Haven't pulled the thermostat, but this isn't suspect because the temps regulate back to normal and stay there. I can also sustain the "high temp" where it is at based on load and always bring it back down by unloading the tractor. I could always pull it and check it on the stove, but I need to clean the system regardless
-Water pump appears to be circulating coolant through the radiator properly, whether it's "up to spec" or not, I can't verify. I am doubtful this is the problem.
-Head gasket isn't in the mix as I'm not getting coolant in the oil/white smoke out the exhaust/black floaties in the coolant/or over-pressurization of the coolant from combustion gases
-Have checked temps with a different gauge and am getting up to about ~220F before I start lowering the load. It probably could go higher, but i don't push it at that point
-Oil has been changed recently and is still clean (not overheating from the engine oil)

ipz2222 said:

I was in the same boat with a neglected bx2230. Out of several suggestions, I chose Arm and Hammer washing powder. Drained the radiator, mixed 1 full cup of powder with 1/2 gallon of HOT water. Poured the hot mixture and toped it off with water. Run the eng for at least 1/2 hour. Drain it out, run again, drain, fill, run... 4 to 5 times, gets all the soap out. It was amazeing how clean the radiator was when I finished. Fill with Fleetcharge antifreeze from TSC.

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I've heard about the Arm & Hammer solution - I may have to give that a whirl just from a simplicity and low cost aspect! If it doesn't work - hey I'm not out a whole lot!

GWD said:

Hopefully, you have checked and cleaned the radiator screen and cleaned the exterior of the radiator as well. (You mentioned that this was done.)

But to your question, I use Tri-sodium phosphate (TSP). It doesn't foam and does a great job of cleaning. It doesn't foam either.

http://www.homedepot.com/p/SAVOGRAN-1-lb-Box-TSP-Heavy-Duty-Cleaner-10621/202935861

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Radiator screen is clean

I've used TSP for other projects, but can't say I've ever thought to use it in a cooling system... I know it works well on grease and the likes, but does it work well on scale buildup? I suppose it wouldwork very similarly to the Arm and Hammer as they both have a pH relatively close to each other... Sodium Bicarbonate (aka Arm & Hammer Washing Soda) has a pH of 11.6 where as the TSP has a pH of 12.0. So in theory (all other chemical reactions ignored - I'm not a chemist ), the TSP should work better right?

I agree on not using Draino - too harsh for my liking... has anyone ever tried using one of the many citric acid cleaners? I know is a relativity gentle acid - I use it for cleaning brass for reloading ammo, but not sure if it would be strong enough for scale in a cooling system.

Just thinking out loud at this point...

I'll probably try TSP followed by vinegar if needed. Any idea if I should run the tractor with either of these cleaners in it to get some heat and pressurized circulation into the system or is better just to let it sit?

Heck - maybe I'll just fill the thing with Coca-Cola!!!!

Stubbyie said:

There's more going on in the chemical reactions involved in radiator crud cleaning than can be judged by simply increasing the pH of the cleaning material.

And to further comment on the temperture increase, a rule of thumb (worth what most such rules are) is that a temperature increase of 10-degrees Celsius (approximately 18-degress F) doubles the rate of chemical reaction.

So if you bring your engine up to 170-deg F on the gauge from a cold start of 70-deg F then you have increased the temp 100-deg F so you could expect the cleaning reaction to proceed at approximately 5 times faster in the hot engine than the cold. For our purposes close enough.

So whatever cleaning reaction is going on is happening much faster than you thought and may for that reason be much more aggressive.

As for powdered products, dissolved in water, then used in the cooling system? I think this is a prescription for problems. Temperature and pressure changes inside the engine (pressure drop through the thermostat or through an interior cooling channel) or radiator could conceivably result in that powder dropping out of solution. And which due to chemical and structural changes, the powder once back in solid form may not want to be dissolved back into water. Now a real problem may exist that didn't previously.

Personally, I wouldn't introduce anything into a radiator I cared about other than distilled water or glycol.

I think if an owner really truly thinks the cooling system needs cleaning to that extent their first move should be removing the radiator, having it professionally disassembled and rodded and vatted and cleaned, reinstalling it with pure water and glycol, and then seeing if there is still a problem that the engine itself needs attention.

Offered for continued comment by this knowledgeable community of users.

Please post back your experiences so we may all learn.

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Stubbyie

I agree that none of these methods will yield a radiator as clean as bringing it to a professional to be worked over. I also agree that a new radiator would be an acceptable fix, although a bit more expensive. However, these methods will only clean the radiator and not address the rest of the cooling system. One could go another step and pull the motor, have it hot tanked/magnafluxed and the like to make sure the rest of the cooling system is cleaned, but then costs start getting quite high. There may be other ways that professionals can clean the entire cooling system that I am not aware of (controlled circulation of certain chemicals in a controlled environment could be one )


The purpose of starting this thread was merely to discuss cost saving alternatives to these methods stated above. Something that can help the regular Joe do some wrenching on his tractor at home to help improve his cooling systems efficiency. I understand why you may not want to jeopardize the integrity of your system with the home remedies as discussed so far, but my thoughts are that if I am going to have to pay someone to clean my radiator (or replace it), I might as well give it a low cost whirl at home first! Let's just hope that the gaskets hold up to the chemicals . I just don't want to get too far away from the main topic.

Ok - got sidetracked there... my bad Now on to the theory.

From past chemistry classes, I understand the heat acts as a catalyst to speed up the reaction but didn't know how much - thanks for those rough figures! I didn't know off the top of my head that the speed approximately doubles for every 18F. However, if we are talking mixtures and solutions, wouldn't a powdered cleaner dissolved in water technically be a solution? unless too much powdered cleaner was mixed in and it became more of a mixture... I know it is much more difficult to separate out a solution than a mixture. Essentially the solution would have to undergo a phase change or chemical change that precipitates out the cleaner. This would be a clear example where more cleaner would not work better than the proper amount of cleaner.

I am not sure here, but I wouldn't think the pressure or temperature differentials observed in a cooling system would be great enough to pull the cleaner out of solution. Since the cooling system only gets charged to less than 20 psi, I don't think the pressure differential would be greater than 20 psi would it?

I could see where something would happen if cavitation is a factor, but I wouldn't think that the cleaner would be subject to prolonged exposure to the extreme conditions of cavitation - therefore making this almost negligible.

I wouldn't want to truly "Operate" and "Work" the tractor going through this cleaning process, but merely have it running to get ambient heat into the cooling system to speed up the cleaning process. This would keep some of the more extreme operating conditions out of the picture.

None of this is meant to be contradictory or argumentative to what you have said - merely just thinking out loud and having a discussion.

Either way, I will be trying one or more of the methods previously discussed and will report back what I find! Hopefully I'll be able to get some bore scope images of before and after treatment. It might just be a little while before I get to it because i'm not sure what the meaning of "free time" is these days

Very well put OldeEnglish. Although more work in the long run, I think that is a superior approach to doing everything in one shot.

I guess my thought with running the cleaner through the block was that if I can get most of the scale into suspension it would make it easier to flush out. I am not worried about surface rust building in the cooling passages as it should be somewhat minimal and a thin coating. I am more worried about any kind of lime/calcium deposits or other mineral deposits from a past owner not using distilled water.

My initial thoughts were to run a solution of TSP through the engine using a 5 gallon bucket and a pump as a circulation method. Simply pull the thermostat, drain the cooling system, refill with TSP solution, fill 5 gallon bucket with TSP solution, use pump to introduce solution to the cooling system and have a drain line back to the 5 gallon bucket. I may actually use a couple 5 gallon buckets set up in a weir configuration with a simple improvised filter or two to help solids drop out before being introduced back into the cooling system. When effluent looks clean, drain system and flush with hose.

I do like the idea of pulling the radiator and treating them as two separate systems though. I haven't looked at the cooling passages through the block yet, but I do expect that I will need to introduce some sort of cleaner to the block passages.