Cooling system cleanliness

JasterMereel42 said:
The water pump is weeping, and the mechanic that I took it to when I bought it a month ago said this. I want to do it on my own. I bought this Wrangler as a project and it needs a decent amount of work. I'm thinking of doing the water pump first because it'll help to circulate everything within the cooling system. I know the cooling fluid is old/dirty/rusty. With a bad water pump, I don't know how well it will circulate everything. I've already had the Jeep overheat once.
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for the water pump to be the culprit in an overheat would require significant damage to the impeller via corrosion or cavitation. You know your Jeep though...if you're concerned that you won't be able to avoid reproducing the scenario that led to the previous overheat then it's probably best to just go ahead and drain it, swap the water pump, and then do the thermocure flush.
 
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freedom_in_4low said:
for the water pump to be the culprit in an overheat would require significant damage to the impeller via corrosion or cavitation. You know your Jeep though...if you're concerned that you won't be able to avoid reproducing the scenario that led to the previous overheat then it's probably best to just go ahead and drain it, swap the water pump, and then do the thermocure flush.
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The Jeep has been in my garage for 2 weeks now so I don't really know it that well yet. I'm learning a lot though.

I am probably going to swap out the water pump on Saturday. I have the entire day blocked off to get that done, and I can probably get it done in a single day. I know the Thermocure process takes a few days because it is a lot of waiting around. Once I get the water pump replaced, I'll do the coolant system flush right after that.
 
mrblaine said:
Stop being an engineer for 10 seconds. It takes 2 gallons of coolant and 1 gallon of distilled to get 3 gallons of 70ish/30ish.
Using 3 of the empty jugs that held distilled, pour the coolant into them until all 3 have the same amount in each. Top off all 3 to full with 1 gallon of distilled. Now you have 3 gallons of pre-mix 2/3 coolant and 1/3 distilled.
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I was going to reply to @freedom_in_4low with this Youtube clip, but your reply is better.

 
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P man said:
You guys are making me feel terrible..I can't say I've ever flushed a cooling system let alone put this much thought into it.
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1. I've pretty much only ever done it on Jeeps, but I also subject my Jeeps to much worse situations and I don't want problems in a place I can't just call roadside assistance.

2. Every time I take something off, I clean it. Since I'm replacing the water pump anyway, I might as well clean it up inside. I've already had the fan, shroud, and water pump pulley out in the driveway soaked with Simple Green and scoured with the pressure washer.
 
psrivats said:
Mathologer is a youtube treasure. One of the channels who's content that I enjoy 100% and I have been watching for years.
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my username is actually supposed to be 'hbar' as in Planck's constant over 2 pi, but my Mac autocorrected to to 'hear' w/o me noticing. Which is simply to say that (a) I love the math/physics content like that and (b) my attention to detail apparently sucks.
 
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hear said:
my username is actually supposed to be 'hbar' as in Planck's constant over 2 pi, but my Mac autocorrected to to 'hear' w/o me noticing. Which is simply to say that (a) I love the math/physics content like that and (b) my attention to detail apparently sucks.
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You can get @Chris to change your username if you ask nicely :)
 
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I was pretty pissed when I clicked the confirmation email and saw that it had autocorrected me. b is nowhere near e on the keyboard, so it's not like I fat fingered it.

Back on topic: both TJ's are running around 199-201F in this crazy heat. I figure I need to flush them, but I also don't want to mess with what is clearly working great.
 
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ok, so here's the update.

I may be going overboard, but I'm so pissed that I'm doing this again 2 years after doing it that I'm not messing around. To minimize the time spent with tap water inside, I will ONLY be using it for flushing out the thermocure. Everything else will be distilled. It's only $1.22 a gallon at my local Walmart anyway.

First I drained the radiator, into a funnel with several sheets of paper towels and a coffee filter, to see if it came out clean enough to reuse. It doesn't look half bad just looking at the stream as it's poured, but in a white bucket it still looks like butt.

PXL_20230721_191139227.jpg


Next I filled with distilled water, ran it up to temp and shut it down when the top radiator tank was hot. Drained that out, added the thermocure, and then filled it back up with distilled water again, and put straight distilled in the overflow reservoir. Went and tooled around in town running some errands for a couple hours.

Got back and the thermocure appears to be doing it's job based on what has made it's way to the reservoir.
PXL_20230721_212831287.jpg


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I'd be curious what Thermocure would come out looking like if I ran it on a brand new car fresh off the dealer lot. Would it still be black? Or does that actually mean it's doing something?

I was really hoping to do the water pump and thermostat tomorrow because it'll only be in the upper 80s but I guess I'm gonna have to wait until Monday to give the Thermocure the time it needs. I'm running out of weekends before my Colorado wheeling trip and I still have more to do, like grease my freakin Johnny Joints.
 
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I found a photo of inside the cylinder head water jacket behind the thermostat housing from the last time I did this. At the time I deemed the amount of remaining rust to be acceptable because it was waaay cleaner than I ever got my 99 to be. But maybe I needed more time? Or another round of thermocure?

IMG_20210205_220421.jpg


For contrast, this was in the block behind the water pump on my 99. It's coolant was dirty again pretty much immediately after flushing and replacing the pump, thermostat, radiator, and hoses (so all the junk was in the block and head)

20180811_220711.jpg
 
Last edited:
Just for a point of reference of you overthinking things…my 04 has 156,000 miles on it, and I’ve never done thermocure, or a flush, or anything like that. It’s on the list, but hasn’t happened. I have replaced the cooling system, but no flush. I don’t even know if my block drain would come out!

Anyway, it still runs with the needle just below the 1 in 210. The inside of the block is uncoated cast iron. It is going to rust. It will be OK.
 
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freedom_in_4low said:
ok, so here's the update.

I may be going overboard, but I'm so pissed that I'm doing this again 2 years after doing it that I'm not messing around. To minimize the time spent with tap water inside, I will ONLY be using it for flushing out the thermocure. Everything else will be distilled. It's only $1.22 a gallon at my local Walmart anyway.

First I drained the radiator, into a funnel with several sheets of paper towels and a coffee filter, to see if it came out clean enough to reuse. It doesn't look half bad just looking at the stream as it's poured, but in a white bucket it still looks like butt.

View attachment 443291

Next I filled with distilled water, ran it up to temp and shut it down when the top radiator tank was hot. Drained that out, added the thermocure, and then filled it back up with distilled water again, and put straight distilled in the overflow reservoir. Went and tooled around in town running some errands for a couple hours.

Got back and the thermocure appears to be doing it's job based on what has made it's way to the reservoir.
View attachment 443292

View attachment 443293

I'd be curious what Thermocure would come out looking like if I ran it on a brand new car fresh off the dealer lot. Would it still be black? Or does that actually mean it's doing something?

I was really hoping to do the water pump and thermostat tomorrow because it'll only be in the upper 80s but I guess I'm gonna have to wait until Monday to give the Thermocure the time it needs. I'm running out of weekends before my Colorado wheeling trip and I still have more to do, like grease my freakin Johnny Joints.
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Thermocure turns black as it interacts with ferrous. Not sure what the process is but if you leave a chunk of iron in a bucket of Evaporust too long, it greatly decreases the effectiveness of it and turns the liquid black.
 
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freedom_in_4low said:
I found a photo of inside the cylinder head water jacket behind the thermostat housing from the last time I did this. At the time I deemed the amount of remaining rust to be acceptable because it was waaay cleaner than I ever got my 99 to be. But maybe I needed more time? Or another round of thermocure?

View attachment 443333

For contrast, this was in the block behind the water pump on my 99. It's coolant was dirty again pretty much immediately after flushing and replacing the pump, thermostat, radiator, and hoses (so all the junk was in the block and head)

View attachment 443335
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When we do it, this is almost good enough.
1690037872976.png
 
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Mike_H said:
Just for a point of reference of you overthinking things…my 04 has 156,000 miles on it, and I’ve never done thermocure, or a flush, or anything like that. It’s on the list, but hasn’t happened. I have replaced the cooling system, but no flush. I don’t even know if my block drain would come out!

Anyway, it still runs with the needle just below the 1 in 210. The inside of the block is uncoated cast iron. It is going to rust. It will be OK.
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I'd not be as much concerned with some non flaky surface rust as I am with the scale that appears similar to heavy calcium build-up.

I suspect we deal with a lot more abused cooling systems that have been run with tap water than others do. Also why we run the Prestone drive around flush and then the Thermocure. I don't think the Thermocure removes as much scale as the Prestone does.
 
P man said:
It's understandable that you may be feeling frustrated or uncertain about whether or not to flush your cooling system.
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I don't have a subjective view. I'm not going to spend several hours swapping on new parts and wind up with other than perfect performance out of them by not making sure I've given them the best possible chance to perform perfectly and I can't do that with a rusty scaled out block.

I did get a brain tickle as I was writing that which reminded me of a gent that moved here from your neck of the woods with his TJ. I noted that he was only going to the store at night when the temps dropped below 90 and asked him what was up with that silliness? I can't drive it without it overheating so I go at night with the heater on full blast to be able to make it there and back.

Was it doing this before? No, never an issue up north but as soon as I get here, it starts. We did our normal stuff to it including the flush and he was then able to do all the normal stuff in our heat.

Point being, a lot of stuff slips by in different regions that won't fly for one second in others. Our cooling systems have to work very well.
 
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Mike_H said:
Just for a point of reference of you overthinking things…my 04 has 156,000 miles on it, and I’ve never done thermocure, or a flush, or anything like that. It’s on the list, but hasn’t happened. I have replaced the cooling system, but no flush. I don’t even know if my block drain would come out!

Anyway, it still runs with the needle just below the 1 in 210. The inside of the block is uncoated cast iron. It is going to rust. It will be OK.
Click to expand...

A great deal of my concern is rooted in the fact that it doesn't seem like my other vehicles have this issue, and haven't had nearly as much maintenance.

I've developed a hypothesis of how I got here though. I think that maybe last time (February 2021) I didn't give the prestone enough time, maybe needed another round, and there was a pocket of rust protected by scale.

Last September on a wheeling trip to Colorado my cooling system suddenly changed behavior. Previously it would warm up quickly to 195, maybe settle in to 192 and hang there if I was idling, or come back up and stay in the 190s unless it was super hot. On day 2 of that trip and ever since, it's been getting to 180 and just stays there unless it's at least 90-100 outside. My hypothesis is that a chunk of rust broke free on that trip, a flake got stuck in my thermostat holding it open enough that it ALMOST warms up, and the rest of it disintegrated and contaminated the entire coolant charge with rust dust.

I should be tearing into it tomorrow so I'll at least be able to check my thermostat theory.
 
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