Coolant System Flush with Thermocure

[djy5005]

I'm posting a step-by-step on how I plan to flush the system. Please advise if any of the steps may be incorrect - it looks like I'm posting steps that aren't defined in the "How-To", which is the only reason I'm starting a new thread.

In the next few weeks I plan to do a coolant system flush with a product I've read about called thermocure (https://www.evapo-rust.com/thermocure/) (https://www.amazon.com/dp/B00R74I5UY/?tag=wranglerorg-20).

I plan to drain the whole block. I already bought this tool (https://www.amazon.com/gp/product/B00FRLBF4M/?tag=wranglerorg-20) to remove the block drain plug.

Here's the following steps I plan to take.
0) Catch as much antifreeze as I possibly can in a container throughout this process.
1) Pull the block drain plug.
2) Pull the thermostat and replace housing. Use new gasket, even if temporary, to create new seal.
4) Run TAP (Hose) water through the system to get as much crap out as possible. The only reason I'm using tap water at this point is because I plan to use the Thermocure. Figured there's no reason to throw $$$ away since there's no benefit to the distilled water, yet.
(EDIT - Added step) 4a) Open up drain petcock on the radiator to drain radiator as well.
5) Remove heater core hoses. Forward flush and reverse flush the heater core with TAP (hose) water.
6) Replace heater core hoses.
7) Fill system with Thermocure and TAP (hose) water. (Still no thermostat installed)
8) Run the car for a few hours in the driveway or drive around town. (Possibly leave it in the block for a week since I can only work on it during weekends.)
9) Pull the block drain plug again once the engine cools down.
10) Use only DISTILLED water, and run the system again for a few minutes. No more tap water to prevent any mineral deposits.
11) Drain again. Repeat steps 9 and 10 until the fluid drained is clear.
12) Replace thermostat.
13) Fill with 50/50 mix (using distilled water, of course). Let system Burp as needed and then top off when necessary.

Questions:
A) When using the themocure, should I use Distilled water instead, and if so, why? I'd assume that tap water wont cause any scaling since it's just in the system for a few hours, and the thermocure is probably able to get rid of any hazards from the minerals in the water.
B) Is it safe to drive around town without that thermostat in there for a few hours? I would assume it wouldn't do anything bad, just maybe not get as good gas mileage for the couple days it's like that. It's not a Daily driver, so it'll just be used for that day (or the days I'm working on it).

 

[Jerry Bransford]

Is your engine currently overheating? Do you see evidence of hard water/calcium buildup inside the radiator when you look inside under the radiator cap after dropping the level enough to see the core underneath?

That product won't help overheating that isn't directly caused by large amounts of calcium build up that would only be caused by using tap water instead of distilled water.

If your engine is overheating, have you eliminated all other possible sources like a sticking thermostat or a bad water pump?

And I'll never add tap water to the cooling system, I use strictly distilled water purchased by the gallon at my grocery store.

 

[djy5005]

Is your engine currently overheating?

Nothing's overheating at all - this is just a regular preemptive maintenance job.

Since I've had it, the coolant is green, and its also pretty dirty (which could potentially be rust buildup). I've no idea if the PO used tap water vs. distilled at all, either. I'd rather clean the system (and the overfill tank) fill it with G-05 and know that it was done right, since I have no documentation on anything that was done with the jeep before I bought it.

Would it be beneficial to use both the Thermocure, followed by a descaling product (separately used) to do this job? It looks like on some descaling product instructions that they use a hose (which I'd assume is tap water) to flush the system, assuming that the block drain is opened. I don't see why tap water would be bad to use (with the added benefit of water pressure being pumped through the system), as long as distilled is used in the endgame.

(EDIT) I guess I could see the use of distilled water and any descaling product used, just running the engine and having the water pump do the work of pushing it through the system. If I did that, though, I still don't see a need to use distilled water if i do the thermocure BEFORE i use any descaling agents, as the descaling agent would grab any leftover mineral deposits with it.

 

[djy5005]

Do you see evidence of hard water/calcium buildup inside the radiator when you look inside under the radiator cap after dropping the level enough to see the core underneath?

I actually haven't looked at this yet to determine if there is any calcium buildup - the radiator was relatively new when I bought it though, so I'm not sure if this would be a true indicator if there wasn't some other buildup throughout the system as well.

 

[Jerry Bransford]

Look inside the top of the radiator as suggested above, you'll be able to tell if there's calcium build-up where Thermocure etc. would be warranted. If there are no visible calcium/hard water deposits up up on top where you can see it under where the radiator cap is, odds are they're not anywhere else either. A flush wouldn't hurt but unless you see a problem, I wouldn't also add the descaler.

 

[Chris]

A) When using the themocure, should I use Distilled water instead, and if so, why? I'd assume that tap water wont cause any scaling since it's just in the system for a few hours, and the thermocure is probably able to get rid of any hazards from the minerals in the water.

Never, ever use tap water. Always use distilled water, even if you're just flushing it. That's my opinion and I stand by it. You don't want any tap water (or other water with minerals) trapped in your cooling system, as it will cause issues over time with rust, among other things. Distilled water is usually 99 cents or less at the grocery store, and two gallons would be more than enough to flush the system.

B) Is it safe to drive around town without that thermostat in there for a few hours? I would assume it wouldn't do anything bad, just maybe not get as good gas mileage for the couple days it's like that. It's not a Daily driver, so it'll just be used for that day (or the days I'm working on it).

If you drive around without the thermostat in there, you're going to have coolant running through your system constantly, and it's going to take forever to get up to operating temperature. I don't see any reason it wouldn't be safe to do for a short period of time though.

 

[Mr. Bills]

I wouldn't use Thermocure or a descaler. In your case it would be a fix looking for a problem. Similarly, I would not change the thermostat if there are no signs of failure or overheating. It is better to subscribe to the motto "if if ain't broke don't fix it" than "fix it 'til it breaks."

Here is what I would do: Drain the old coolant, refill with distilled water, circulate well via some routine driving with the heater on, drain again, refill with distilled water again. Repeat the process until water runs clear, measuring the approximate volume of water drained out the final time. Two cycles should be enough, three if the coolant was in really bad shape or if one has OCD tendencies.

Assuming that 50% of the total cooling system was drained on the final cycle (1/2 of 10.5 qts.), you could add that amount of concentrated G-05 coolant to the distilled water remaining in the system and call it a day. However, that is seldom the case so you will need to do the math and adjust the amount of concentrated coolant accordingly to end up with a 50/50 mix of coolant and distilled water. (Don't worry about whether it is exactly a 50/50 mix, just get as close as you can.) Then drive normally until the air bubbles work themselves out and adjust the coolant level accordingly.

 

[djy5005]

Just a note before I address previous posts: The thermocure shown in my first link is a rust-related product, not calcium. Would rust only become a concern if there was calcium buildup as well (i.e. there'd have to be calcium to cause rust)? I'd assume an iron block with around 250k miles might have rust even if there was no calcium buildup.

Look inside the top of the radiator as suggested above, you'll be able to tell if there's calcium build-up where Thermocure etc. would be warranted. If there are no visible calcium/hard water deposits up up on top where you can see it under where the radiator cap is, odds are they're not anywhere else either. A flush wouldn't hurt but unless you see a problem, I wouldn't also add the descaler.

Will do - By "drop the level" in the previous post, I assume you meant that I would just need to use the drain petcock and not the block drain to see it, so I'll pull it and check when the radiator is drained.

If you drive around without the thermostat in there, you're going to have coolant running through your system constantly, and it's going to take forever to get up to operating temperature. I don't see any reason it wouldn't be safe to do for a short period of time though.

I wasn't planning on it getting up to temperature - just to get all the distilled water run through the system to flush out any cavities.

Similarly, I would not change the thermostat if there are no signs of failure or overheating.

Assuming that 50% of the total cooling system was drained on the final cycle (1/2 of 10.5 qts.), you could add that amount of concentrated G-05 coolant to the distilled water remaining in the system and call it a day.

The reason I was going to pull the thermostat was just so that I could flush the entire system as a whole in a single shot - getting all of the distilled water run through the system so I can drain it in one shot and not have to worry about calculating the right amount of coolant left in the system because the thermostat isn't open (not that it's hard, I know). I don't mind eating the cost of the gasket, and it's not like it's hard to get to.

 

[Mr. Bills]

I think you are making this project more difficult than it needs to be.

You don't need to give your cooling system a chemical enema if there are no indications that it needs one. Similarly, there is no reason to remove the thermostat unless it isn't working properly.

 

[Altonymous]

I had heating issues with mine.. did a flush with Thermocure, no more heating issues.. but I can't get the smell out.. I've been through 20 gallons of distilled water.. still the smell. I haven't tried running distilled water through it constantly with the motor running and the drain valve on the radiator open. Can you see any issues with this to try and get it clean?

The smell is putrid and it's getting really old.

(Hoping that resurrecting an old thread doesn't cause any hi-jacking issues and keeps the information about Thermocure consolidated. Let me know if I should create a new post and I will.)

 

[hyperdub808]

I love Thermocure! It cleaned out my cooling system really good!