Improving the cooling on our TJs

TexasTJ2004

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deal fellow TJers, I am looking into my TJ (4.0,42RLE) in which I am running new radiator, new coolant, new Hayden fan clutch, with properly working AC, and a winch mounted in the front. Thermostat and water pump seems to operate as expected, so don’t believe that I need to replace them.
What I see is that in stop and go traffic it gets always beyond 210, the same when parked in idle, even at the evening, with 87F outside.
I am in Houston area, so temperatures here easily reach 100F during the day. Also, as we all know the summers are getting hotter, so I am thinking about how to improve the cooling.
I have one step already on my schedule,. Which is adding Derale cooler for 42RLE, which will prevent the 42RLE from overheating.
Other step that is planned is to install louver (Poison Spyder), that will help to reduce the heat soak and heat buildup in the engine bay.
But, I am thinking about enhancing the engine cooling, using the following;
To tap into hot coolant line that go into the cabin, add a 3 way valve, that enables to route t he coolant into cabin or to additional cooler, and additional small radiator, with electric fan. I want to put somewhere near the Derale cooler for transmission, so that it takes away the heat from the engine Bay Area.
Before I jump into anything like, wanted to hear the opinion of experts here, I am sure that a lot of folks through about it before.

FFF453FC-F91C-4996-B280-DD0D103216B8.jpeg
 

Chris

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Aside from cooling the transmission (which you should do), you’re trying to solve a problem that doesn’t exist.

Your TJ was designed to operate just fine in the Texas heat. As long as your cooling system is maintained then you’re just fine.

Again, trying to solve a problem that doesn’t exist. That may not be what you want to hear, but it’s the truth.

As for louvers, I like they way they look and they did slightly drop the temps under the hood, but it wasn’t anything revolutionary.

The temp gauge in your photo is 100% normal for this time of the year in traffic.
 
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TexasTJ2004

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For some reason I thought that it should never go beyond 210F and that it will blow up in a minute.
How do you identify potential overheat then? Is it when the temperature goes further from 210F?
 

CharlesHS

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As Chris posted above; the factory cooling system is designed to operate is a variety of temperatures WHEN the system is operating properly.
IF that is the operating temperature of the engine even when the outside air temperature is 87* as you posted above; then there is something that is not performing properly.
When you replaced ALL the parts listed above; did you use a chemical cleaner when you flushed the engine?
Take another look at the cooling system parts that you didn't replace previously.
I would recommend replacing the thermostat with a quality part such as STANT; ensure there is a pop it valve in the thermostat body or drill a 1/16" hole in the flat section of the body to assist in the system burp after refilling the coolant. You do not need to drain the system when replacing the thermostat; only lower the coolant level in the radiator (about 2 quarts) below the upper radiator hose.
Check into replacing the temperature sensor on the thermostat housing with a OEM Mopar sensor.
 
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TexasTJ2004

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As Chris posted above; the factory cooling system is designed to operate is a variety of temperatures WHEN the system is operating properly.
IF that is the operating temperature of the engine even when the outside air temperature is 87* as you posted above; then there is something that is not performing properly.
When you replaced ALL the parts listed above; did you use a chemical cleaner when you flushed the engine?
Take another look at the cooling system parts that you didn't replace previously.
I would recommend replacing the thermostat with a quality part such as STANT; ensure there is a pop it valve in the thermostat body or drill a 1/16" hole in the flat section of the body to assist in the system burp after refilling the coolant. You do not need to drain the system when replacing the thermostat; only lower the coolant level in the radiator (about 2 quarts) below the upper radiator hose.
Check into replacing the temperature sensor on the thermostat housing with a OEM Mopar sensor.

I did not do proper chemical flush. I assume that I should do it then.
The thermostat is the original one from 2004.
 
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TexasTJ2004

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Radiator is 1 year old, I bought it from AutoZone, radiator cap is Mopar one, and Hayden 2771 was installed today.
 

CharlesHS

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IF your thermostat is from 2004; then it most certainly needs replacing.
The STANT thermostat is the best alternative to the Mopar thermostat.
IF you installed a knock off radiator instead of the Mopar OEM radiator; then I would recommend doing a search to find the Mopar radiator.
When you talk to most TJ owners on this forum; they will recommend the Mopar OEM radiator as the best part to install.
 
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TheBoogieman

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For some reason I thought that it should never go beyond 210F and that it will blow up in a minute.
How do you identify potential overheat then? I

That's what the red line is for, before the 260 mark. My Jeep survived 13 years in TX.
Red McCombs (2).jpg
 
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Jerry Bransford

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Is this the right part for TJ thermostat?
Mopar 5202 8186AC, Engine Coolant Thermostat https://a.co/d/0P2xaPm
Yes that's the correct thermostat, it has the specified 195 degree rating per the Mopar parts guide.

When your Autozone Duralast radiator fails, I'd not take them up on their "lifetime" warranty and replace it with another Duralast. I'd try to find a Mopar, hopefully there will still be some somewhere by then. Duralast is not a good brand and their radiators don't cool as well or have the quality of the Mopar. Don't take their lifetime warranty to mean it has good quality, it just means they'll give you another when it fails. That may not seem like a good business model but it is. By the time most people get around to replacing things like their radiators, water pumps, etc. they typically don't own their cars for long afterward so AutoZone doesn't end up having to replace it again after its first purchase. Us Jeep owners do tend to keep our Jeeps a long time so when replacing critical parts like that it's best to pay a little more to get better quality than Duralast. Mopar if you can find it for critical parts like radiators, water pumps, sensors, etc.
 
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TexasTJ2004

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IF your thermostat is from 2004; then it most certainly needs replacing.
The STANT thermostat is the best alternative to the Mopar thermostat.
IF you installed a knock off radiator instead of the Mopar OEM radiator; then I would recommend doing a search to find the Mopar radiator.
When you talk to most TJ owners on this forum; they will recommend the Mopar OEM radiator as the best part to install.

I have installed Idle Air Contoller from Autozone like 3 month ago, and it failed miserably in less than a month, not being able to stabilize idle properly. Then I looked for Mopar one, and found out that it is 90 day waiting for delivery. Ordered from amazon 3 cheap chinese Idle Air Controllers for same price as 1 autozone piece, installed one and keep 2 more in glovebox. The chinese garbage works fine, and I can replace it in 30 minutes if it goes bad.
Judging from my IAC expirience, the AutoZone radiator is going to fail same way:).
 
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TexasTJ2004

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Yes that's the correct thermostat, it has the specified 195 degree rating per the Mopar parts guide.

When your Autozone Duralast radiator fails, I'd not take them up on their "lifetime" warranty and replace it with another Duralast. I'd try to find a Mopar, hopefully there will still be some somewhere by then. Duralast is not a good brand and their radiators don't cool as well or have the quality of the Mopar. Don't take their lifetime warranty to mean it has good quality, it just means they'll give you another when it fails. That may not seem like a good business model but it is. By the time most people get around to replacing things like their radiators, water pumps, etc. they typically don't own their cars for long afterward so AutoZone doesn't end up having to replace it again after its first purchase. Us Jeep owners do tend to keep our Jeeps a long time so when replacing critical parts like that it's best to pay a little more to get better quality than Duralast. Mopar if you can find it for critical parts like radiators, water pumps, sensors, etc.

Thanks Jerry. I will source a Mopar radiator and put it in.
 
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xXDavidCXx

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Other step that is planned is to install louver (Poison Spyder), that will help to reduce the heat soak and heat buildup in the engine bay.

Read this first before getting the poison spyder louver.

 
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TexasTJ2004

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Read this first before getting the poison spyder louver.

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Thanks for the pointer. I have already ordered poison spyder.
It might sound laughable, but i think that the louver in addition to reducing the heatsoak, for which it is ideal (a lot of vents right on top of the fuel rail/exhaust manifold), it will also improve aerodynamics. The problem with TJ is that the fan pulling the air through the radiator, but the air pretty much nowhere to go.
However, adding two side vents like this guy added, might be a good idea. Cheap and good.
 

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TexasTJ2004

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The entire area under the engine is WIDE-open. Vents won't help engine cooling in the least.

But they will decrease the resistance on the airflow path, and hot air bubble build up under the hood in next to firewall.
However, I agree with you that the main problem is improperly operating cooling system, mainly because of old clutches, thermostats, knock off radiators, lack of proper cleaning etc.
I think that the best test is try to run the jeep w/o thermostat, and see whether it can cool itself just fine. If it does, then the thermostat is the problem.