How to flush the cooling system on your Jeep Wrangler TJ

[zscott]

This is a project I plan on tackling this weekend if given the chance and some decent weather. I've got a few questions regarding this process. The first is with the heater core.

Flush Heater Core

1. Found on the heater core inlet hose where I wanted the TEE fitting. Made 2 cuts removing a 3/4" section. This helps make up for the width of the TEE.
2. Use a funnel to put a gallon or less of distilled water through the hose.
3. Disconnected the heater core outlet hose and reverse flush the heater core.

Use the clear plastic tube to direct any coolant flushed from heater core hoses into the drain pan.

1. In the above-mentioned steps, what is the purpose of installing the "TEE Fitting"? Is this just to help with the refill process, or does it assist in the next time you go to flush the system? Maybe it helps with flushing out the air in the system?

2. I see you want to pour distilled water into the TEE?

3. I don't think I understand what reverse flush of the heater core means.

Lastly, I have a general question on the flush process here. When flushing the entire system with water, would it not be okay to completely remove the thermostat during however many flushes required until you get clear water coming out? Also when going through these multiple flushes to clear the water, do I need to repeat draining the engine block each time or can I just drain the water out of the radiator/reservoir?

Thanks in advance!

 

[01TJ-Blues]

Hello everyone,

I'm doing the flush cooling system on my tj 4.0 1999.

Does anyone know what is the diameter and type of thread of the drain plug?

I want to replace it with an exagonal head cap.

Thank you in advance for your answers

3/8 pipe thread.

 

[zscott]

Delay my previous post in this thread. I went ahead and tackled this project yesterday. I knew I was overthinking it and well a quick read on what a backflush was solved my curiosity. I will say, I bought 10 gallons of distilled water and I needed way more than that. Also what wasn't mentioned, was just because you can open your radiator cap doesn't mean that the coolant that is sitting in your engine isn't enough to make you sprint out from under your jeep once you pull that drain plug. All in all, great write up.

 

[hear]

Can anyone post a picture of this TEE setup? I'm not understanding how it works, or what advantages it gives.

I'll answer my own question, hopefully this is what everyone is talking about. I used it, and it seemed to work great. Only cost about $3

[URL]https://www.walmart.com/ip/Pre...jB7_pAyRNvLYXHG80emlOlq_s6aZPt7RoCZjcQAvD_BwE[/URL]

 

[Viking Jeeper]

I'll answer my own question, hopefully this is what everyone is talking about. I used it, and it seemed to work great. Only cost about $3

https://www.walmart.com/ip/Prestone...jB7_pAyRNvLYXHG80emlOlq_s6aZPt7RoCZjcQAvD_BwE

I may have posted this in the thread already but I had one of them disintegrate on me Christmas Day in rual IL with no cellphone and no parts or tools.

 

[invmgmt]

So, if it's not the Prestone one, where do you get the "Tees" referenced?

 

[hear]

So, if it's not the Prestone one, where do you get the "Tees" referenced?

you might be able to cobble something together from home depot fittings?

 

[illest83]

Just did this to my new to me 2003 TJ. Wasn’t too hard. I didn't add a Tee to the lines. Just put a funnel on them and pour distilled water in. Did the same thing throught the thermostat with engine plug in, and then with the engine drain plug out. Ended up replacing the radiator, thermostat, fan clutch, and belt while I was in there.

 

[TBeeson87]

What if I cannot get the engine block drain plug out? Looks like the prev owner already partially stripped the plug so I am hesitant to try and remove it. Is there another way to flush the block? I am only doing the flush since I have no idea how old the coolant it...

Could I drain the radiator/clean the reservoir/flush the heater core then run the system with distilled water then re-flush it all?

 

[BlueC]

Could I drain the radiator/clean the reservoir/flush the heater core then run the system with distilled water then re-flush it all?

That will work, it just might not be as thorough as pulling the plug out. I suggest using a product like Evapo-Rust Thermocure, or your choice of coolant system flush, to get it cleaner in there.

 

[mrblaine]

That will work, it just might not be as thorough as pulling the plug out. I suggest using a product like Evapo-Rust Thermocure, or your choice of coolant system flush, to get it cleaner in there.

It is always as thorough when done correctly. I think we need a refresher course on the difference between rinsing out the cooling system and actually doing a flush that cleans the scale and rust out because I'm fully convinced that most of these folks believe that a good rinse is doing something good. It isn't.

 

[TJosh02]

So I finished overhauling my entire cooling system last week and then drove it ~400+ miles with a couple of trail rides as well. Everything worked fine and I am running about 10-15 degrees cooler than before. These threads were really helpful for someone like myself with little engine mechanic knowledge.

 

[JasterMereel42]

So I finished overhauling my entire cooling system last week and then drove it ~400+ miles with a couple of trail rides as well. Everything worked fine and I am running about 10-15 degrees cooler than before. These threads were really helpful for someone like myself with little engine mechanic knowledge.

Could you list out the steps that you did for your cooling system overhaul?

 

[TJosh02]

All the threads here detail it better than I could. I watched a number YT videos as well to make sure I understood correctly. I don't have any experience working on engines but I am fairly engineering minded and handy, so it wasn't hard.

I replaced:

• Fan Clutch
• Thermostat
• Radiator
• Hoses
• Water Pump
• Gaskets
• then used this thread to flush everything (radiator didn't need it obviously, since new one went in and engine mostly drained taking out the water pump and thermostat).

I did this in an underground parking garage without access to a hose or electrical outlet, so I think pretty much anyone can do it. I did need a fan clutch tool to break the bolt. Bought it on Amazon. If I had access to angle iron, I would have made one like some here did. Probably would have worked as well or better.

https://wranglertjforum.com/threads/jeep-wrangler-tj-cooling-system-overhaul-faq.3397/

 

[JasterMereel42]

All the threads here detail it better than I could. I watched a number YT videos as well to make sure I understood correctly. I don't have any experience working on engines but I am fairly engineering minded and handy, so it wasn't hard.

I replaced:

• Fan Clutch
• Thermostat
• Radiator
• Hoses
• Water Pump
• Gaskets
• then used this thread to flush everything (radiator didn't need it obviously, since new one went in and engine mostly drained taking out the water pump and thermostat).

I did this in an underground parking garage without access to a hose or electrical outlet, so I think pretty much anyone can do it. I did need a fan clutch tool to break the bolt. Bought it on Amazon. If I had access to angle iron, I would have made one like some here did. Probably would have worked as well or better.

https://wranglertjforum.com/threads/jeep-wrangler-tj-cooling-system-overhaul-faq.3397/

You and I come from similar backgrounds where we haven't worked on cars much, but are engineering minded.

I did pretty much refresh my cooling system by replacing the water pump, t-stat, t-stat housing, radiator, and hoses over the last few weeks. I didn't do the fan clutch because mine seems to be fine.

I just need to do the Prestone+Thermocure flush and then I think I'm done with the cooling system.

This weekend's project is to drop the skid plate, clean it up, change out the fluid in the transfer case, change out the fluid in the trans, and put on a new trans oil pan and gasket.

 

[CoopJeep]

No heat in my 2003 Jeep TJ. Changed thermostat, 195 degree, checked heater vane door and actuator booth OK, flushed heater with water and no difference. Used Blue Devil radiator flush and cycled reverse flush with drill pump for 45 minutes. Forward flush for half hour, finished with water flush. Now have lots of heat.

 

[JasterMereel42]

No heat in my 2003 Jeep TJ. Changed thermostat, 195 degree, checked heater vane door and actuator booth OK, flushed heater with water and no difference. Used Blue Devil radiator flush and cycled reverse flush with drill pump for 45 minutes. Forward flush for half hour, finished with water flush. Now have lots of heat.

Sounds like your heater core was clogged up and the flush cleaned it out.

 

[jcw]

Would anyone be able to distill (no pun intended) this thread down to an actionable checklist to take with consideration into replacing the cooling system (radiator, water pump, fan clutch, thermostat etc)? Also considering a thermocure flush just to cover all bases. Thanks

 

[Viking Jeeper]

Would anyone be able to distill (no pun intended) this thread down to an actionable checklist to take with consideration into replacing the cooling system (radiator, water pump, fan clutch, thermostat etc)? Also considering a thermocure flush just to cover all bases. Thanks

Sounds like a great idea. Post it up here!

 

[JasterMereel42]

Sounds like a great idea. Post it up here!

And until that happens, I guess the first post in this thread will have to suffice.