How to flush the cooling system on your Jeep Wrangler TJ

[Stinkbug]

Quick question on flushing chemicals like Prestone or Blue Devil… I have limited time to work on my Jeep these days. If I drain, flush with distilled water, then add one of these chemicals can I safely drive it occasionally, but leave it in for the next 7-8 days without damaging things like an aluminum heater core?

 

[mrblaine]

Quick question on flushing chemicals like Prestone or Blue Devil… I have limited time to work on my Jeep these days. If I drain, flush with distilled water, then add one of these chemicals can I safely drive it occasionally, but leave it in for the next 7-8 days without damaging things like an aluminum heater core?

I'm not a fan of leaving it quite that long but only because I have the same concerns. That said, unless you have swapped it out for the aluminum version, your heater core is copper and brass, or was when it came from the factory. I can't prove that a longer interval damages anything though.

 

[Stinkbug]

I'm not a fan of leaving it quite that long but only because I have the same concerns. That said, unless you have swapped it out for the aluminum version, your heater core is copper and brass, or was when it came from the factory. I can't prove that a longer interval damages anything though.

Thanks, I guess I will do the flush and just run distill ed water for a few days. Then just add the chemical a day or two prior to the day I can flush it again. You also caused me to look through my receipts and I found I replaced the heater core with OEM back in 2011. I guess the picture I had in my mind was the aluminum evaporator in the box with it…

Edit: Both chemicals seem to be available locally, do you prefer one over the other?

 

[mrblaine]

Thanks, I guess I will do the flush and just run distill ed water for a few days. Then just add the chemical a day or two prior to the day I can flush it again. You also caused me to look through my receipts and I found I replaced the heater core with OEM back in 2011. I guess the picture I had in my mind was the aluminum evaporator in the box with it…

Edit: Both chemicals seem to be available locally, do you prefer one over the other?

I have used the Prestone drive around version many times with success. The last time I explained that to someone, none of the pictures they sent me matched the product I have used. That means it changed and I'm not familiar with the new stuff or they could not find what I used. I don't have any experience with other similar products.

 

[Ardalan11B]

I just went through all this and used the liquimoly radiator cleaner. No acids or alkalines per them, I think it did a great job. I also ran it for about 30min and let is sit for a few days. Did flush with a ton of distilled water post cleaner, until not foamy. Everything looks amazinly clean now. Last owner mixed coolants, looked like pink and gold/orange. I changed thermostat (what a Pain in the ass, so much dried up rtv everywhere), overflow tank, and cap at same time.

 

[Viking Jeeper]

Quick question on flushing chemicals like Prestone or Blue Devil… I have limited time to work on my Jeep these days. If I drain, flush with distilled water, then add one of these chemicals can I safely drive it occasionally, but leave it in for the next 7-8 days without damaging things like an aluminum heater core?

When my Jeep was about 15 years old but maybe 25,000 miles on it and relatively new to me. I decided to do a flush and drive it for a few days. A no notice wheeling trip came up about 1.5 hours each way there plus any time spent there. I did not plan to drive that much with the flush in there but I thought it would be ok. My heater core started leaking on that trip and has been bypassed since, still same radiator. I will never be able to prove it was the flush that caused the core to fail but I am not going to do it like that again.

 

[mrblaine]

Did flush with a ton of distilled water post cleaner, until not foamy.

No reason to do all that flushing with distilled. Use hose water until it runs clear and a couple rounds of distilled to dilute the hose water.

 

[BlueC]

Quick question on flushing chemicals like Prestone or Blue Devil… I have limited time to work on my Jeep these days. If I drain, flush with distilled water, then add one of these chemicals can I safely drive it occasionally, but leave it in for the next 7-8 days without damaging things like an aluminum heater core?

I've never used the two products named, but I have used Thermocure a few times. The instructions specifically state the product can be used "up to several days", although a full week might be pushing it. If you need additional time, you might want to give this a try. https://www.evapo-rust.com/thermocure-cooling-system-radiator-rust-remover/

 

[Ardalan11B]

No reason to do all that flushing with distilled. Use hose water until it runs clear and a couple rounds of distilled to dilute the hose water.

I hear ya, my hose water makes me nervous, my tds is super high as the water in my parts is atrocious. For the $20 in distilled water I probably went through, if all it does is make me feel better, I'm ok with it lol.

 

[mrblaine]

I hear ya, my hose water makes me nervous, my tds is super high as the water in my parts is atrocious. For the $20 in distilled water I probably went through, if all it does is make me feel better, I'm ok with it lol.

I fully regret offering sound advice.

 

[Jeme]

I used thermocure and it made my coolant rust color regardless of how much or how long I flushed my system.

 

[Kerry]

Im having trouble finding the coolant drain plug on the engine block of my 05, can any 05 owners help me out?

 

[MikeE024]

Im having trouble finding the coolant drain plug on the engine block of my 05, can any 05 owners help me out?

I drained my 05 block many times by placing an extension between the Pre-cats on the left side. That same plug is now covered up by the aftermarket exhaust manifold I installed.

 

[bigjeffb]

For the life of me I can't get the block drain plug out. Breaker bars, penetrating oil, heat, you name it.
Am I just wasting time doing a flush (I was going to use Blue Devil) if I can't get the plug out? I just keep picturing all sorts of crap accumulating down there that will never come out....

 

[chili_pepper]

For the life of me I can't get the block drain plug out. Breaker bars, penetrating oil, heat, you name it.
Am I just wasting time doing a flush (I was going to use Blue Devil) if I can't get the plug out? I just keep picturing all sorts of crap accumulating down there that will never come out....

I flushed mine without removing the block drain plug shortly after I purchased it. Wasn't aware of the plug at the time.

 

[BlueC]

For the life of me I can't get the block drain plug out. Breaker bars, penetrating oil, heat, you name it.
Am I just wasting time doing a flush (I was going to use Blue Devil) if I can't get the plug out? I just keep picturing all sorts of crap accumulating down there that will never come out....

Flush it as best as you can. Don't worry about forcing that plug out. Using the block drain will just help get more of the crud out. Getting 90% of the crud out is better than getting none of the crud out.

 

[MikeE024]

For the life of me I can't get the block drain plug out. Breaker bars, penetrating oil, heat, you name it.
Am I just wasting time doing a flush (I was going to use Blue Devil) if I can't get the plug out? I just keep picturing all sorts of crap accumulating down there that will never come out....

Forget the plug ever existed and do the flush.

Thermocure is likely worth doing as well since it should deactivate the rusted bits in the bottom of the block.

 

[hear]

I'm sure I have a reply in this thread about also not being able to get that block drain out. I gave up, figuring that stripping it or breaking it would end up worse than whatever draining benefit I might gain.

 

[Garvin]

This was incredibly helpful, just flushed the coolant on my 97 TJ. Thank you.

 

[carmangary]

I flushed used thermocure and flushed my coolant system really well back in January until in ran clear. I went through a lot of hose water, distilled water, and then fresh coolant. I drained drained the radiator last week (in June of same year) and my coolant was looking kind of grayish and there is black bits floating around in it. The black stuff is sludegy, not hard. I sent some coolant to Blackstone for an analysis and they said there was no trace of oil or engine exhaust and that the coolant was fine, as far as coolant goes.

I think the best thing for TJs and their rust prone blocks is just to do a bleed and feed every 6 months to a year. A bleed and feed is basically just draining the radiator and refilling it. If you do that periodically enough, the bad stuff gets diluted enough to stay fresh. You can buy a gallon of concentrated prestone and a gallon of distilled water for well under $20 so it doesn't cost much. It takes about 2.4 gallons to drain the radiator and refill.