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Improving the cooling on our TJs

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TexasTJ2004

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this is exactly my point. We need to have cold AC, as cold as the FSM defines in AC spec. The problem is that I think that most of us simply don’t get there, and that the main reason for it is weak cooling is that the cooling system of the engine is kinda weak.
 
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TexasTJ2004

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View attachment 345237
I’m going to be a jerk here. One site or two listing “discontinued” doesn’t mean they aren’t out there. Literally Amazon has a listing with 1 left in stock right now.

You have to search a little. I’m sure eBay has some, I’m not going to look there too, but if you want your Jeep to work right, I’d get on it asap.

Thanks a lot. I kinda missed the part that when Mopar discontinues, some still have stock.
 

mrblaine

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this is exactly my point. We need to have cold AC, as cold as the FSM defines in AC spec. The problem is that I think that most of us simply don’t get there, and that the main reason for it is weak cooling is that the cooling system of the engine is kinda weak.

The cooling system in stock form is not even remotely close to a tiny bit weak and is in fact, quite the opposite. I've worked on many of them, folks know I do so they get with me to solve cooling issues. I don't supply parts, so I give them a parts list. Guy shows up with the parts, we pull the fan shroud to start the job and I notice mud in the radiator. We pull the radiator and notice that there is only a clear spot free of mud right in front of the fan blade about the size of a dinner plate. I ask him about it and he relates it has been almost a year since he went mudding in Azusa. In the meantime his rig has had no cooling issues until it started to warm up to 90+ and he was running up the mountain to Big Bear during which it was just starting to move a couple of needle widths to the right of 210.

We put the pressure washer on high flow low pressure, cleaned all the mud out, did a quick flush with some distilled, put in new Mopar coolant and sent him on his way with a promise to let us know how it worked. It did not run warm on the way up to Big Bear on hotter days. That doesn't happen with a limited capacity system nor will a limited system keep the rig running fine until very warm days running up the hills.
 
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TexasTJ2004

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The cooling system in stock form is not even remotely close to a tiny bit weak and is in fact, quite the opposite. I've worked on many of them, folks know I do so they get with me to solve cooling issues. I don't supply parts, so I give them a parts list. Guy shows up with the parts, we pull the fan shroud to start the job and I notice mud in the radiator. We pull the radiator and notice that there is only a clear spot free of mud right in front of the fan blade about the size of a dinner plate. I ask him about it and he relates it has been almost a year since he went mudding in Azusa. In the meantime his rig has had no cooling issues until it started to warm up to 90+ and he was running up the mountain to Big Bear during which it was just starting to move a couple of needle widths to the right of 210.

We put the pressure washer on high flow low pressure, cleaned all the mud out, did a quick flush with some distilled, put in new Mopar coolant and sent him on his way with a promise to let us know how it worked. It did not run warm on the way up to Big Bear on hotter days. That doesn't happen with a limited capacity system nor will a limited system keep the rig running fine until very warm days running up the hills.

Thanks a lot for your explanation.
I am on path of installing everything Mopar, with one tiny problem - only Mopar radiators for TJ 2004 that I can find are for manual, not for automatic. I have Derale transmission oil cooler ( the one that goes on the frame in the back, waiting to be installed in my garage), but I don’t think that I can just skip having transmission oil passing through engine radiator. I mean I can take manual radiator, without oil cooler in the bottom, install it and have oil cooled by Derale only. The problem with this approach is that transmission oil will be get to working temperature fast enough.
If you can advise me with these 2 questions, I will pray for your Carma:
1. What do you think about sourcing manual radiator and relying on Derale only? This will get it cold enough, I believe,. But will not heat it up at all.
2. If not Mopar (only manual ones left), is there any other radiator that you would recommend?
 
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TexasTJ2004

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As @cpwolf said they are available. Ordered one on Tuesday night from Amazon (manual transmission) and it was at my door Friday mid day in a factory unopened box brand new.

Yeah, I can buy the manual transmission one right now as well. The problem is that I have automatic, and these are nowhere to be found (the real Mopar part, not copies).
 
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mrblaine

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Thanks a lot for your explanation.
I am on path of installing everything Mopar, with one tiny problem - only Mopar radiators for TJ 2004 that I can find are for manual, not for automatic. I have Derale transmission oil cooler ( the one that goes on the frame in the back, waiting to be installed in my garage), but I don’t think that I can just skip having transmission oil passing through engine radiator. I mean I can take manual radiator, without oil cooler in the bottom, install it and have oil cooled by Derale only. The problem with this approach is that transmission oil will be get to working temperature fast enough.
If you can advise me with these 2 questions, I will pray for your Carma:
1. What do you think about sourcing manual radiator and relying on Derale only? This will get it cold enough, I believe,. But will not heat it up at all.
2. If not Mopar (only manual ones left), is there any other radiator that you would recommend?

I looked today and bought a TJ MOPAR for an 05 which just has different connections at the radiator trans cooler that can be adapted. Keep looking, they are out there. Amazon even has one.
 
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TexasTJ2004

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I looked today and bought a TJ MOPAR for an 05 which just has different connections at the radiator trans cooler that can be adapted. Keep looking, they are out there. Amazon even has one.

Just bought this guy on Amazon:

55037653AC​

It is for 2005 automatic, but as you advised, I will adapt the transmission cooling lines.

83836FBA-0830-46A5-BE4C-873F608291A5.png
 
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TexasTJ2004

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I purchased the manual radiator and then added a trans cooler.

I thought about this option, as I am installing separate Derale cooler for my transmission. But, the problem with this approach is that the engine radiator is supposed to heat up the oil to the working temperature, and with separate cooler it will never happen.
 

TNHEADDUCK

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Dec 3, 2015
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Music City USA
I thought about this option, as I am installing separate Derale cooler for my transmission. But, the problem with this approach is that the engine radiator is supposed to heat up the oil to the working temperature, and with separate cooler it will never happen.

Interesting, I never knew the trans fluid used the radiator coolant to get it up to temp. On all of the purpose built rock crawlers I have owned and built I have used trans coolers with fans that come on when I switch my radiator fans on after startup, never had any issues with any of them :unsure:.
 

mrblaine

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I thought about this option, as I am installing separate Derale cooler for my transmission. But, the problem with this approach is that the engine radiator is supposed to heat up the oil to the working temperature, and with separate cooler it will never happen.

Not that you should but there are thermostatically controlled transmission cooler bypass valves specifically made for that problem. They circulate the fluid back into the transmission until it gets warm enough to open the bypass which then shunts it through the cooler and then back into the transmission.
 

JPHikr

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Jun 27, 2020
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261
Location
East of Nowhere Airzona
Try about a 3 oz of water soluble oil in the radiator.

It will pull the temp down and keep the block from rusting.

Another trick that I have been doing for over 40 years.
 

cpwolf

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Not that you should but there are thermostatically controlled transmission cooler bypass valves specifically made for that problem. They circulate the fluid back into the transmission until it gets warm enough to open the bypass which then shunts it through the cooler and then back into the transmission.

I’ve never owned an automatic Jeep, but is this a real problem? The Trans fluid needs to be heated? I’m ignorant to this for sure.

Would letting the Jeep sit and idle like I have to on this CJ 304 do the trick?

You said “ not that you should” so I assume you wouldn’t necessarily. Is this a solution looking for a real problem?
 

mrblaine

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I’ve never owned an automatic Jeep, but is this a real problem? The Trans fluid needs to be heated? I’m ignorant to this for sure.

Would letting the Jeep sit and idle like I have to on this CJ 304 do the trick?

You said “ not that you should” so I assume you wouldn’t necessarily. Is this a solution looking for a real problem?

That means I know they exist, I know why they are used and if you are contemplating elimination of the radiator aspect, that may be a way to solve the issue in a cold region.

It is a real problem where it gets cold.
 

radiationfool

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Jul 24, 2022
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3
Location
Washington
My water pump on my '05 went out, and the radiatorblew it's top as a result. I have since replaced the water pump with one from FlowKooler, the fan clutch with Hayden 2771, the radiator with an aftermarket aluminum model from ExtremeTerrain, as well as the thermostat and hoses. I ran a chemical flush, then flushed with water before replacing with Zerex coolant for Mopar vehicles.
Now the engine overheats constantly, regardless of ambient temperature or traffic. By the time it's warmed up, it's already overheating. The gauge goes past 220 and then keeps moving toward the red zone. I am unable to drive more than a few miles before having to pull over.
The overflow reservoir overflows a bit, but then goes back down when cooling off. I run the heater at full blast, but the air doesn't feel hot. The oil appears normal in color, so I don't think the block is cracked or the head gasket damaged.
Any ideas what might be happening here? I know many are going to say I should have gone with Mopar, and you're right about that. Even so, the TJ should be drivable regardless, even with a slightly higher engine temp. I am in the PNW, and we are seeing temps in the 70-80 degree range. Overheating in this weather must be due to something more than non-OEM parts.