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?'s about Cooling System Swap


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Most of my questions are pretty simple stuff, but like I said before I'm not a mechanic nor do I claim to be one, however I do enjoy upgrading my own stuff (89 MJ) with the help of the comanche club of course :clapping: . So my question is: 1. What all is involved in switching cooling systems to where I don't have the old pressurized system? 2. How do I do it? 3. Is it a difficult swap? 4. How much does it cost? Thanks all help is greatly appreciated.

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The "old" radiator and the "new" radiator are exactly the same size and both operate at the same (or nearly the same) pressure. I am constantly mystified by the number of people who seem to think changing to the new style ("open") cooling system is in any way an up-grade.

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I just considered it an upgrade because it was newer. All I was thinking of doing was replacing the old cooling system with a newer one. One that you actually put coolant in the radiator with out the pressurised bottle. Yes I know they operate at the same pressure.

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Instead of using an "open" radiator, I spliced the water inlet from a 99 durango 4.7 into the upper rad hose. Still swapped over the newer heater valve. System works great, no temp issues, but if I were to do it again id consider swapping radiators.

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Instead of using an "open" radiator, I spliced the water inlet from a 99 durango 4.7 into the upper rad hose. Still swapped over the newer heater valve. System works great, no temp issues, but if I were to do it again id consider swapping radiators.

 

I pretty much did the same, although I got rid of the heater valve entirely - haven't had any problems with the heat or A/C yet. Got an overflow bottle from AutoZone:

 

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So basically all I have to do is get a radiator (that you put the coolant directly into) and swap them out. That's it? Thanks

No, that's not all you have to do.

 

If you have air conditioning, the auxiliary electric fan is controlled by a sensor that mounts in the left hand (driver's side) tank of the radiator. Because the auxiliary fan is controlled by the ECU on the 1991 and newer systems, most of the "open" style radiators don't have a bung into which to install the sensor. So then you're faced with trying to figure out how you're going to get the aux fan to turn on when needed.

 

There have been a LOT of different ways proposed over the years. Most of them didn't work.

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[because the auxiliary fan is controlled by the ECU on the 1991 and newer systems, most of the "open" style radiators don't have a bung into which to install the sensor.

 

Disagree. Most all XJ/MJ replacement radiators are now truly universal - fit all. Coolant ports for the AW4 are there, the bung hole for the Renix aux fan sensor is there in the left tank, as well as the HO fill port. Just make sure before you buy.

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[because the auxiliary fan is controlled by the ECU on the 1991 and newer systems, most of the "open" style radiators don't have a bung into which to install the sensor.

 

Disagree. Most all XJ/MJ replacement radiators are now truly universal - fit all. Coolant ports for the AW4 are there, the bung hole for the Renix aux fan sensor is there in the left tank, as well as the HO fill port. Just make sure before you buy.

Some aftermarket rads are indeed "universal" -- with both the radiator/fill cap and the temp sensor bung. One of the most popular is the GDI, and the last time I bought one it did NOT have the bung. We know because the radiator shop didn't understand the significance when I ordered one for a 1988 Cherokee so he just ordered the same one he usually orders, and most of what he had been seeing was the new style. It had a radiator cap but no sensor bung, so we had to send it back.

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I hooked my ele fan to a toggle switch in the cab. Along with a 160 thermostat my jeep runs real cool. Only use the eletric fan when I'm in the woods. Still plan on puttin vents in my hood.

 

Acualy used the tranny power toggle. haha since i have swaped to a 5 speed. On power my fan is on.

226597_1806328597907_1230685607_31857996_2505790_n.jpg

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Instead of using an "open" radiator, I spliced the water inlet from a 99 durango 4.7 into the upper rad hose. Still swapped over the newer heater valve. System works great, no temp issues, but if I were to do it again id consider swapping radiators.

 

I pretty much did the same, although I got rid of the heater valve entirely - haven't had any problems with the heat or A/C yet. Got an overflow bottle from AutoZone:

 

 

yeahthat.gif Been done on all the XJs and MJs my "band" owns. Works well.

 

We got all the parts from Summit - filler neck and overflow bottle delivered for bout $55 +/-

 

got to keep stock closed radiator. Truthfully, the radiator isn't the problem, the pressure bottle is.

 

Eliminate the bottle, fill it an alternative way (remote filler neck) move on...

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  • 1 month later...
Instead of using an "open" radiator, I spliced the water inlet from a 99 durango 4.7 into the upper rad hose. Still swapped over the newer heater valve. System works great, no temp issues, but if I were to do it again id consider swapping radiators.

 

I pretty much did the same, although I got rid of the heater valve entirely - haven't had any problems with the heat or A/C yet. Got an overflow bottle from AutoZone:

 

 

 

 

Sorry to bring back an old thread but what is the black knob in your heater hose? Is that a shut off valve? Wanting to do this to mine as my bottle is cracked.

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It's part of the Prestone cooling system flush kit that I got at Walmart for $3. It's just a plastic tee with a cap on it. I had no idea what the condition of the cooling system was when I first got this truck, so I had that's been installed since before this swap. You don't need it, I just didn't want to get rid of it.

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