So many coolant flushes!

Jfdeucetx

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Long time reader, first time poster. Very appreciative of all the knowledge poured out on these forums.

I hope ya'll can help. I've tried everything!

Jeep TJ 2.5 bought used in 2020 with about 130,000k miles on it. Drained the coolant and started doing flush cycles on it with distilled water and radiator flush chemicals. I have probably ran Presetone radiator flush 4-5 times and Thermocure at least twice. With the Prestone I would leave it in a few days and then flush out. With the Thermocure, once I left it in a few days and another time I left it in for about a month. Between those chemical flushes I have run countless gallons of distilled water through. It is not a stretch to say that I am over 50 flushes, does this put me into crazy territory?

Early along the way I replaced most of the cooling system after the radiator developed a leak - radiator, thermostat, water pump, hoses, gaskets. I am at my wits end on this. I am ready to button it up for the winter and put some coolant in but just can't bare to do it with the water still coming out muddy brown almost every time. More recently I did back flush the heater core and even tried a flush cycle with white vinegar.

Most likely rust in the engine block. Any other ideas to try? Should I just move on and try another series of treatments in a year or 2?
 
I'm a little confused. What is your current problem that you are worried about? Just not clear water coming out, or are you having temp issues?

If it's just dirty coolant, there should be a coolant drain on the block. That is usually the low spot of the internal coolant system, and where crap likes to accumulate. Open it up and start flushing with a water hose. You might need to remove the thermostat to really get in there.
 
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With the Thermocure, once I left it in a few days and another time I left it in for about a month.

A month? Here's what their web site says:

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If I were you, I'd call Evaporust (the manufacturer) and ask if the mud-colored water could be a result of running it too long...
 
I'm a little confused. What is your current problem that you are worried about? Just not clear water coming out, or are you having temp issues?

If it's just dirty coolant, there should be a coolant drain on the block. That is usually the low spot of the internal coolant system, and where crap likes to accumulate. Open it up and start flushing with a water hose. You might need to remove the thermostat to really get in there.

no temp issue. just dirty water that will not clear up. it just doesn't seem right to have it running so dirty like that but maybe that's what I am going to have to accept at some point.

I have run it with thermostat pulled and I have done sprayed water directly through with a hose. I've been unwilling to pull the drain plug from the block after hearing of others having issues breaking the plug or getting it back in.
 
A month? Here's what their web site says:

View attachment 375960

If I were you, I'd call Evaporust (the manufacturer) and ask if the mud-colored water could be a result of running it too long...

the dirty water pre-dates the extended run with the thermocure and I did many other cycles before trying the extended run. I've read of others doing extended runs with the product without issue. based on my understanding of the way the product works (chelating agent) I am not concerned with it causing the ongoing issue. When I first started cycling it out after the extended it run, it was a mess of gray and black sludge. However, that has since cleaned up and it is back to lighter tinted brown/black water coming out.
 
no temp issue. just dirty water that will not clear up. it just doesn't seem right to have it running so dirty like that but maybe that's what I am going to have to accept at some point.

I have run it with thermostat pulled and I have done sprayed water directly through with a hose. I've been unwilling to pull the drain plug from the block after hearing of others having issues breaking the plug or getting it back in.

If you don't want to pull the plug, and you aren't having any other issues, I'd just fill it and go. Maybe cycle some out at each oil change for a while to start clearing things later.

Make sure you're turning the heat on full blast when you're doing the flush to clear out the heater core.
 
the dirty water pre-dates the extended run with the thermocure and I did many other cycles before trying the extended run. I've read of others doing extended runs with the product without issue. based on my understanding of the way the product works (chelating agent) I am not concerned with it causing the ongoing issue. When I first started cycling it out after the extended it run, it was a mess of gray and black sludge. However, that has since cleaned up and it is back to lighter tinted brown/black water coming out.

I don't know why you wouldn't just pick up the phone and call the manufacturer, since they know their product better than anyone on the Internet would. I just called Evaporust for you (actually, the parent company is CRC - the big chemical company) because I was curious and as the Latin in my avatar says "semper discens," I'm always trying to learn new things:

1668198381681.png


Anyway, I called their tech support number (800-521-3168) and spoke to a rep named Ben. Here's what I've learned:

I asked Ben what would happen if someone ran Thermocure for a month, and he said they really don't know if it would cause permanent damage, but what it would likely do is turn all the steel it touched black as the chelating agent worked and worked. The black is apparently a result of the chelation process (there are several different chemical reactions occurring, and one of them results in a carbon compound left behind on the surface when the iron is chelated out of the steel. Carbon in elemental form is black, so that is why the surface turns black.

In addition, if you ran just water and Thermocure (no coolant) for that month, he suspected that iron oxide would start to reform since there are normally corrosion inhibitors in the coolant that prevent this. That is why they recommend adding Thermocure to your coolant - to prevent new iron oxide from forming. Iron oxide has a red/brown tint. He said that flushing after a month with water and Thermocure in the system would be washing these two compounds off the surface slowly, so you could see tints anywhere from red to brown and grey to black, and anywhere in between. He had no idea how long it would take to see clear water.

So, Ben at CRC believes that the tinted water you are seeing is very likely a result of running Thermocure too long. He emphasized that they really don't know if permanent damage can be done, but his advice was to flush with distilled water as best as you can to ensure mineral-free water is in there, then follow the normal procedure to refill with distilled water/anti-freeze at the appropriate ratio, and put it back in service to see if you have any lasting effects.

Good luck!
 
I asked Ben what would happen if someone ran Thermocure for a month, and he said they really don't know if it would cause permanent damage, but what it would likely do is turn all the steel it touched black as the chelating agent worked and worked. The black is apparently a result of the chelation process (there are several different chemical reactions occurring, and one of them results in a carbon compound left behind on the surface when the iron is chelated out of the steel. Carbon in elemental form is black, so that is why the surface turns black.

That is what happens when using EvapoRust, and how you know it is "spent". I've left heavily rusted parts in an EvapoRust bath for a few days before and everything turns black, but it just wipes off or washes off with something like brake clean/acetone. Of course, you can't just wipe off internal surfaces. I suspect the OP has no real damage, just that residue washing off.
 
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That is what happens when using EvapoRust, and how you know it is "spent". I've left heavily rusted parts in an EvapoRust bath for a few days before and everything turns black, but it just wipes off or washes off with something like brake clean/acetone. Of course, you can't just wipe off internal surfaces. I suspect the OP has no real damage, just that residue washing off.

Ben actually gave that same Evaporust story as part of his explanation to me because the products are of similar chemical composition. Apparently, one of their most popular calls is regarding black parts left in Evaporust for too long...
 
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when i flushed my coolant system with thermocure i left it in for two days. then filled with distilled water and ran that for a day. drained radiator and block. then installed new mopar radiator filled with zerex go-5 and distilled water mixed 50/50. thermocure was black as tar when drained and straight distilled water was a bit lighter color when drained. jeep maintains good temp. and that makes me happy.
 
FWIW, I was also hesitant to pull the drain plug. I didn't flush mine 50 times, but quite a lot between the Prestone, distilled water, Evaporust, distilled water, chasing thermostat housing leaks, etc.

Once I gathered up the courage to do it, pulling that drain plug was remarkably easy and simple, assuming you have the right drain plug wrench.
 
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The 8mm isn’t expensive. I’d advise get it, do it right, especially if you’re worried about it at all.

Hate to say, but you have to read the directions, if they say couple days, now you’ll have black deposits and you’re stuck with not knowing if it’s clean for a while.
 
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