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Closed cooling system upgrade with Mac's Radiator expansion tank questions


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So I bought an 89 Comanche, plan to start a thread soon, but it already had the cooling system completely redone.  It's got a brand new radiator, hoses, thermostat, and water pump...

 

It has the original pressurized tank and I wanted to upgrade that, so I decided I wanted to get the expansion tank from Mac's Radiator.  It will mount in the stock location and I can use the new nice radiator.

 

It's expensive, but I'm fine with that to keep all the rest stock.

 

http://macsradiatorshop.com/miscellaneous/replacment-jeep-radiator-fill-tanks.html

 

So my question is now I need an overflow tank, and I've read about tons people have tried, but I am trying to figure out which overflow bottle is used below, it looks like a great fit.

 

overflow.jpg

 

 

Also, once I use this new expansion tank I assume I will fill things up differently.  With the pressurized tank you wanted it about half full when cold and had to struggle to bleed the system a little.  With the new expansion tank, shouldn't I fill the expansion tank all the way up to the top and then the overflow tank half full and bleed the system like a newer XJ open system?

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The best expansion tank to get is a OEM Mopar that is for a Jeep with a 2.5 liter 4 cylinder. There were some on ebay a while ago. And yes fill just as you described. Also do the burp by removing the temp. sending unit on the back of the head.

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http://www.ebay.com/itm/Jeep-CHRYSLER-OEM-84-90-Cherokee-2-5L-L4-Engine-Coolant-Recovery-Tank-52003213-/271879570919?hash=item3f4d4905e7&vxp=mtr

 

There are still some for sale. Mopar doesn't make these anymore and I think they are better than the ones from Crown. I had a Crown one that leaked. What makes this bottle nice is all the mounting holes are already there, it just bolts in with 2 little screws.

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Mine came with a new radiator also or I would have bought a newer model with the fill neck in the rad.  This is what I used  much cheaper and if you shop around and check the size of your hose the link is just the style you may find one cheaper. http://www.ebay.com/itm/Moroso-63740-Radiator-Hose-Filler-Inline-Aluminum-Natural-1-5in-1-25in-/261934147245?hash=item3cfc7de6ad&vxp=mtr

I removed the tank and the mess of hoses including the heater valve which is not needed and ran two standard heater hoses just like the newer XJ`s.  I used a overflow tank like the one in your picture same spot but have upgraded to a 2.5 overflow for a better fit just havent installed it yet.

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Awesome, I ordered that just now... I keep reading conflicting info, some say in an 89 with 4.0 it fits right in, others say they have to move some stuff around like egr stuff and something else, we will see.

 

Also, since the system will be open, can't I burp it by just keeping overflow full? No need to unscrew temp sensor anymore right, just take time heating and cooling and keeping levels good and it will normalize itself, that's all I do on my CJ and my old newer XJ with open systems.

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http://www.ebay.com/itm/Jeep-CHRYSLER-OEM-84-90-Cherokee-2-5L-L4-Engine-Coolant-Recovery-Tank-52003213-/271879570919?hash=item3f4d4905e7&vxp=mtr

 

There are still some for sale. Mopar doesn't make these anymore and I think they are better than the ones from Crown. I had a Crown one that leaked. What makes this bottle nice is all the mounting holes are already there, it just bolts in with 2 little screws.

I wish I had thought of the 2.5L overflow bottle when I did my expansion tank upgrade.

 

Live and learn.

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Awesome, I ordered that just now... I keep reading conflicting info, some say in an 89 with 4.0 it fits right in, others say they have to move some stuff around like egr stuff and something else, we will see.

 

Also, since the system will be open, can't I burp it by just keeping overflow full? No need to unscrew temp sensor anymore right, just take time heating and cooling and keeping levels good and it will normalize itself, that's all I do on my CJ and my old newer XJ with open systems.

 

You can get rid of all the egr stuff to make room. Just remove all the plastic hoses and whatever and cap off where they went with rubber caps. Its a whole lot of stuff that doesn't  do anything.  You will also have to relocate your ballast resistor, but that's easy too.

 

I would still recommend removing the temp sender to burp.

 

Forgot to say good choice on the Macs. What's the saying? "Buy once cry once"  You will never have a problem with it.

 

Wish I could post some pics, good luck. 

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  • 6 years later...

Just got the Mac’s overflow tank installed. I see that people are using the 2.5L overflow and installing it over by the air box. My only question

is, isn’t that too long of a run? Has anyone used the 97-01 XJ overflow? Anyone have any pics of either set up? 
PFA

C38EF6FF-C54D-4B2B-87FA-E43E9C311AFD.jpeg

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2 hours ago, Rubikahn said:

Just got the Mac’s overflow tank installed. I see that people are using the 2.5L overflow and installing it over by the air box. My only question

is, isn’t that too long of a run? Has anyone used the 97-01 XJ overflow? Anyone have any pics of either set up? 
PFA

C38EF6FF-C54D-4B2B-87FA-E43E9C311AFD.jpeg

Yes install the 2.5 expansion bottle by the air cleaner. Mounting holes are already there. Run your hose alone the fire wall and behind the washer fluid bottle. Works just fine.

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Ok, so I got the 2.5L expansion tank and some hose. For some reason the cap didn’t come with the tank, and it says it’s no longer available. What did everyone use for a cap? The original cap from the 4.0 overflow tank does not fit on the 2.5L tank.

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On 8/14/2021 at 5:17 PM, Rubikahn said:

Gotcha, I’m still running a closed system 

 

Once you use the Macs tank with the 2.5 expansion bottle you have an open system. Fill the Macs tank to the top and the expansion bottle between the high and low marks.

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23 hours ago, PIKE said:

 

Once you use the Macs tank with the 2.5 expansion bottle you have an open system. Fill the Macs tank to the top and the expansion bottle between the high and low marks.

Didn’t even think of it that way, duh… thank you 

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