How to flush the cooling system on your Jeep Wrangler TJ

Ericict said:
If you can find a local radiator shop, ask them to pressure check, and clean it. If all ok, no need to replace. That's what I did and it cost around $30 in Wichita. He told me to overhaul it, the cost was around $100.00 My 02 water pump was leaking when I did mine at 1320k. I did the complete flush and overhaul of the system. Mine was getting hot and I didn't realize the pump was leaking. I was getting drips from the rear main seal that I thought was a seal failure. When you do replace the pump, that's the best time to do it all again. Are you having any over temp issues?
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No, I run at or juuuust a hair above 210 pretty much all the time, just over being in those sweltering KC summers.

In the entire time I've owned it, I had two codes and they appeared at the same time - one related to me needing a new gas cap and one odd random code that indicated transmission running hot months ago. At that time, I did the standard procedure (checked fluid level and color, nothing obvious/odd) and ended up topping it off with some fresh ATF-4. Cleared the code and never had anything since.

I am leaning towards paying Jeep dealer for the full coolant/heater core flush and just eating the cost this time. I have other parts needing to be installed that have been sitting waiting for enough free time and I'd rather take care of this before summer hits since I DD mine.
 
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Not_Invented_Here_ said:
No, I run at or juuuust a hair above 210 pretty much all the time, just over being in those sweltering KC summers.

In the entire time I've owned it, I had two codes and they appeared at the same time - one related to me needing a new gas cap and one odd random code that indicated transmission running hot months ago. At that time, I did the standard procedure (checked fluid level and color, nothing obvious/odd) and ended up topping it off with some fresh ATF-4. Cleared the code and never had anything since.

I am leaning towards paying Jeep dealer for the full coolant/heater core flush and just eating the cost this time. I have other parts needing to be installed that have been sitting waiting for enough free time and I'd rather take care of this before summer hits since I DD mine.
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I'd add that I recently had to pass a state inspection for tag renewal and the results were the same as the first time when I bought it a year ago, leaky valve cover, possible oil pan leak, and mayyyybe the RMS - I personally think it's starting at the top and making its way down/back (fingers crossed heh)

No other leaks indicated on that report though.
 
Thanks guys for the write up I didn't know about the rear drain. I am driving around now with the "slow flush" running through the system and hope it does clear up a lot of the yuck I can see in the radiator. Also the heater isn't as hot as it should be compared to the new core I put in my prior jeep before the wreck. This one isn't leaking at this point.
 
Getting ready to do my coolant and I am trying to piece everything together and order what I need.

OP calls for:
2 gallons OE Mopar coolant
3 gallons distilled water

Link to coolant is dead so I'm trying to figure out, this is concentrate right?

Couple of more questions and my apologies for asking obvious, I'm doing this for the first time and I don't want to mess anything up.


Filling With Coolant
1. Added 5.25 quarts straight coolant to radiator. Topped off with distilled water.
5.25 quarts is 1.25 gallons. So at this point I have 0.75 left then.

2. Once coolant started coming out the TEE I screwed on its cap.
I'm not sure if I want to cut hoses and install this, most likely no but I'm wondering how is coolant coming out of there right now. My understanding is that the engine is still not running?

3. Filled coolant reservoir half way between Full and Add lines with premixed coolant/distilled water.
This is part where I'm confused cause it says premixed coolant/water. So I have 0.75 gallons of coolant left, how much water do I add to it? That container does not look that big so it can take all of it? I don't know how much I needed to top off radiator so what ratio do I mix this in?

4. Started engine and let idle.
5. Squeezed the upper radiator hose a few times trying to expel any trapped air.
6. Made sure radiator was full of water and installed radiator cap. Instructions say to wait until you see water circulating before installing radiator cap. I didn't for some reason.
At this point I should have all my coolant in and then add some water if I don't right?

7. Ran engine for 20 minutes after it reached running temp.
8. Checked for leaks.
9. Stopped engine and let cool.
10. Checked coolant level and mixture ratio.
How do you check mixture ratio?

I found an info that 4.0 takes 10.5 quarts total.
2 gallons of coolant is 8 quarts so to get to 10.5 I would have to add 2.5 quarts of distilled water which is about 0.625 gallons.
Should I not use all coolant? Try to aim more towards 70:30 mix or?
 
I drained my radiator, used Prestone flush with distilled (followed directions), and then drained the radiator and the block. I filled it with distilled and drained 4 more times. The last drained distilled looked ok, but I decided to do a Thermocure flush too. I figured a 15 year old cooling system could benefit from the Thermocure. Thermocure works.

Last distilled flush on right and Thermocure drain on the left.

IMG_0614.jpg
 
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TYTY, If I wanted to pull the inner fender liner I'd have all the room in the world to access that nut. Even as it sits I have a straight shot at it with a 10" extension.
 
I know this is an old thread but my question relates to a cooling system flush - I have in the past drained the radiator and overflow tank, filled with distilled water, ran it for maybe 15 minutes and drained it. I would do this several times before I got a clear color drained. Once I got that, I would then fill with coolant/water mix.

Am I not doing it right or getting a good flush? Never done it with a TJ before but I figured it would be similar???
 
I have flushed my cooling system the same way as you did. It has worked for me many times on many vehicles. I have also mixed Prestone flush in with distilled water and ran it a few days during summer months. Then drained and flushed with water. Just remember to check your antifreeze coolant mix when done.
 
Great to hear. I am doing the flush this weekend. The system seems to be cooling fine so all I was going to do was flush it. Anything I would be smart to change out while it is drained? Hoses look good but should I? T-stat even though it seems to be functioning fine.

I just bought it and have no service records from PO. It has 42k on it

Thanks
 
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In my opinion, others may disagree, but if everything looks good, and is running good? I would just do a good flush. If the flush comes out with chunky stuff or slimy parts, I would change the thermostat to be safe. Its just 2 bolts. Please use a good gasket and 195 degree thermostat. Its a very easy job.
 
I found that actually driving the vehicle was better than letting it sit in the driveway and idle. Get in the Jeep and run down to the store and back, get that fluid sloshing around everywhere.

First Photo is the Second and Third flush after I dumped the Thermocure. Jeep sat at idle in the driveway for 10ish min at 200+

Second Photo is the 4th and 5th flush actually driving the Jeep around. You can see how much darker the 4th flush is.

Flush.jpg


Flush 2.jpg
 
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I totally agree. Thats why i usually run mine for a few days. Thats a great visual aid. Alot of people seem to neglect the cooling system.
 
Bushfamily5 said:
I know this is an old thread but my question relates to a cooling system flush - I have in the past drained the radiator and overflow tank, filled with distilled water, ran it for maybe 15 minutes and drained it. I would do this several times before I got a clear color drained. Once I got that, I would then fill with coolant/water mix.

Am I not doing it right or getting a good flush? Never done it with a TJ before but I figured it would be similar???
Click to expand...

This stuff works great.

https://evapo-rust.com/thermocure/
 
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Thermocure worked for me as advertised. Last weekend I drained enough out of my radiator to put in the full bottle and drove it back and forth to work (12 mile round way trip) all week. Yesterday I flushed with distilled water a few times and the first batch I drained was really nasty looking. Obviously got better with each drain/refill. My heat was very sub-par before this flush, and it will run me out of the Jeep now.

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