How to flush the cooling system on your Jeep Wrangler TJ

[Jeepwx03]

help needed_ so I bough that 8mm square socket sprayed the coolant plug in the engine block with pj blaster and it still rounded off theplug. So I can not get it out. How’s else can I do a complete coolant flush and get what’s in the engine out, or flushed?

Do you have a picture of how rounded it is?

You may need to weld a nut onto the plug, which will heat it up. You could also abandon draining it from that area and use the method I posted to flush it and maybe just do a little less distilled water on your 50/50 mix to try and balance out the mixture.

 

[SSTJ]

help needed_ so I bough that 8mm square socket sprayed the coolant plug in the engine block with pj blaster and it still rounded off theplug. So I can not get it out. How’s else can I do a complete coolant flush and get what’s in the engine out, or flushed?

Hello. Welcome to the forum.

You don't necessarily have to remove that plug. If you flush the system enough times, you will eventually clear out whatever is currently settling in that part of the system.

Your profile doesn't say what year and model your TJ is. Mine is a 97 2.5, and my coolant flush notes are here.

 

[Cheeks]

 

[GregBelleville]

I have a question about the flush process specifically. I've been running Blue Devil and distilled water in my system for a couple days, so I'm getting ready to drain it and flush with distilled water.

My question is whether flushing with the distilled water simply by pouring it into the radiator/heater core hose/temp sensor hole is enough for the flush, or should I be using a garden hose to flush everything with a bit more pressure? If I used a garden hose I would still completely drain the system once the water was running clear, then run distilled through it to make sure the hose water is completely flushed. Then final step would be refilling with 50/50 HOAT coolant/distilled.

Is using the hose a bad idea, even if I plan to completely drain the cooling system afterwards?

 

[JasterMereel42]

@GregBelleville I wouldn't worry about using a garden hose. It is just introducing water with minerals into the cooling system. You are going to have to flush out the cooling system with distilled water so putting hose water into it is just adding more steps to the process.

To speed up the process, many people take out the thermostat. Without a thermostat, the cooling system will start circulating immediately. It is still a good idea to let it run for about 10ish minutes to flush everything around. With a thermostat in, you have to wait for the engine to get up to operating temperature before it starts circulating, and then wait 10ish minutes to have everything circulating.

If you want to speed up the flushing process, there is also an engine block drain plug that you can pull out. It can be a pain to get to though so many people skip it and do a couple of extra flushes instead. It is on the driver side of the block. I've done it a few times and I've found that a 6" extension and a breaker bar are the best things to use to get to it. If you don't remove the engine block drain plug, about a liter of fluid is left in the engine block. The point of doing multiple flushes is to get the remaining fluid in the cooling system diluted to the point that it is practically all flushed out. It is nearly impossible to flush it out completely though so the goal is to get it good enough.

 

[GregBelleville]

@GregBelleville I wouldn't worry about using a garden hose. It is just introducing water with minerals into the cooling system. You are going to have to flush out the cooling system with distilled water so putting hose water into it is just adding more steps to the process.

To speed up the process, many people take out the thermostat. Without a thermostat, the cooling system will start circulating immediately. It is still a good idea to let it run for about 10ish minutes to flush everything around. With a thermostat in, you have to wait for the engine to get up to operating temperature before it starts circulating, and then wait 10ish minutes to have everything circulating.

If you want to speed up the flushing process, there is also an engine block drain plug that you can pull out. It can be a pain to get to though so many people skip it and do a couple of extra flushes instead. It is on the driver side of the block. I've done it a few times and I've found that a 6" extension and a breaker bar are the best things to use to get to it. If you don't remove the engine block drain plug, about a liter of fluid is left in the engine block. The point of doing multiple flushes is to get the remaining fluid in the cooling system diluted to the point that it is practically all flushed out. It is nearly impossible to flush it out completely though so the goal is to get it good enough.

Thanks for the advice! I'll plan to skip the garden hose and instead just pull the TS and will plan to fill and drain the entire system a couple times (running the engine in between drains) to ensure everything is running clear before refilling with coolant.

I've already located the drain plug in the block and removed it when I originally drained the system to add the blue devil stuff.

 

[hear]

If you want to speed up the flushing process, there is also an engine block drain plug that you can pull out. It can be a pain to get to though so many people skip it and do a couple of extra flushes instead. It is on the driver side of the block. I've done it a few times and I've found that a 6" extension and a breaker bar are the best things to use to get to it.

FYI It takes a square drive, but I forget the size. Luckily amazon remembers.

https://www.amazon.com/dp/B00FRLBF4M?tag=wranglerorg-20

 

[JasterMereel42]

Thanks for the advice! I'll plan to skip the garden hose and instead just pull the TS and will plan to fill and drain the entire system a couple times (running the engine in between drains) to ensure everything is running clear before refilling with coolant.

I've already located the drain plug in the block and removed it when I originally drained the system to add the blue devil stuff.

If you remove the engine block drain plug again, and you remove the TS, you can probably get by with just 2 DW flushes before putting coolant back in. I would recommend 3 though just to be safe. You can likely have all of this done in about 60-90 minutes.

 

[JasterMereel42]

FYI It takes a square drive, but I forget the size. Luckily amazon remembers.

https://www.amazon.com/dp/B00FRLBF4M?tag=wranglerorg-20


View attachment 581459

Yeah, I forgot about that. I've got this set for $30 that contains pretty much every single plug that I could potentially need.

 

[GregBelleville]

Well here were the results flushing my Jeep. Far left is the coolant drained at the beginning. Second from left is what I drained this morning after running this stuff with distilled water for a couple days. Probably drove it about 50 miles.

I flushed it 5 times today and still never got it to completely run clear, but it was running noticeably clearer at the end though hard to tell looking at the jugs. This Jeep has 193k miles on it, pretty sure this sort of maintenance has never been done on it.

 

[gbirk]

I did a flush last week after replacing all the hoses. It looked pretty similar to yours.
I did not use a descaller and did three flushes with distilled water and not pulling the plug on the block.

 

[JasterMereel42]

View attachment 581705

Well here were the results flushing my Jeep. Far left is the coolant drained at the beginning. Second from left is what I drained this morning after running this stuff with distilled water for a couple days. Probably drove it about 50 miles.

View attachment 581706

I flushed it 5 times today and still never got it to completely run clear, but it was running noticeably clearer at the end though hard to tell looking at the jugs. This Jeep has 193k miles on it, pretty sure this sort of maintenance has never been done on it.

I went through a similar process whenever I got my TJ. My cooling system was very bad. I flushed it at least 10 times and it still wasn't clear at the end. Good enough is good enough. I would maybe to 2 more flushes and then call it good and fill it up with coolant.

 

[MikeE024]

I went through a similar process whenever I got my TJ. My cooling system was very bad.

I hope your system wasn't as bad as mine was.

I flushed it at least 10 times and it still wasn't clear at the end. Good enough is good enough. I would maybe to 2 more flushes and then call it good and fill it up with coolant.

Yea, you could have done 10+ more rounds of flushes and it still wouldn't have been clear. Just gotta know when to call it. I did many flushes before I finally bent the knee. The only time I see it run clear is when using hose water to flush/back-flush the system.

 

[JasterMereel42]

I hope your system wasn't as bad as mine was.



Yea, you could have done 10+ more rounds of flushes and it still wouldn't have been clear. Just gotta know when to call it. I did many flushes before I finally bent the knee. The only time I see it run clear is when using hose water to flush/back-flush the system.

This was the inside of my radiator when I get my Jeep.

 

[MikeE024]

This was the inside of my radiator when I get my Jeep.

View attachment 581921

Not ideal.

Mine overheated on the first drive (to emissions) and sprung a freeze plug leak (from the rust) within a week of ownership. The story on that got worse, but I'll stop there.

My ECTs are excellent, but I still flush the system once a year because I don't know if it's wise for me to go longer than that. I'm currently running a higher coolant ratio so we'll see if that helps.

 

[Captain Phoenix]

Yeah, I forgot about that. I've got this set for $30 that contains pretty much every single plug that I could potentially need.

Do we have a need for any of those on a TJ other than the 8mm engine block drain plug or are the others just for other automotive needs?

 

[MikeE024]

Do we have a need for any of those on a TJ other than the 8mm engine block drain plug or are the others just for other automotive needs?

FWIW, I got the square 8mm to remove the plug and then replaced it with an internal hex version...the plug stays on the hex tip way better providing an easier install.

Edit: you may want to spray the original plug with some liquid wrench to aid with the removal.

 

[CJ with a TJ]

Flushed mine recently, now I have to figure out what to do with about 10 gallons of old coolant mix. I thought that the local parts stores would take it, but nope, no coolant.

 

[MikeE024]

Flushed mine recently, now I have to figure out what to do with about 10 gallons of old coolant mix. I thought that the local parts stores would take it, but nope, no coolant.

I’ve read different potential options for Boston.

 

[CJ with a TJ]

I’ve read different potential options for Boston.

View attachment 620620

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Appreciate the tips!!!