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Improving the cooling on our TJs

mrblaine

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From what I've read, at least in computer applications, the heat pipes used have sintered metal bonded to the inside and they use it since it's very cost effective. But I'm no expert in this area and I'm curious to know what other methods are used in other applications that @freedom_in_4low may know more about.


I've always understood sintered parts to be pressed into a mold and then heated up to bond the particles in place. The parts always have a distinct look that is very smooth but porous. The bubble stones in aquariums are typically sintered as are lots of fuel filters. I got confused by the just dumping in of the metal powder around a mandrel.
 

Ericshere03

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Running 180 thermostat cannot be a solution. For sake of experiment, I even ran w/o a thermostat at all, it didnt change anything compared to running with thermostat.
Don’t want to be a boring engineer (which I am as a matter of fact), but you cannot cheat thermodynamics (but you can hack computer SW or HW :) )
The difference between 180F and 195F thermostats is just in a spot where the flow of coolant to radiator will start. The moment that Coolant reaches 210F, it does not matter whether the coolant started to flow at 180F or 195F.
Simple equation of how much heat engine generates per second, and how much radiator can dissipate in a same second.

Engineer to engineer … you forget to include “Duty Cycle” in your thought process … the thermostats job isn’t to wait to get to its set point and stay open. It should be modulating flow through the radiator …

It seems that on our Jeeps the cooling system/thermostat is running wide open once it’s warmed up.

In my experience with classic cars and true analog gauges and much better designed cooling systems. A thermostat change WILL in fact lower the engines operating temperature.

To get super technical, not only does a 195 degree thermostat offer lubrication and wear advantages, also the temperature differential between the coolant and the atmosphere is greater allowing the cooling system to move more energy out of the coolant.

So, I do not believe a thermostat should be part of any sort of “repair”, rather our cooling system capacity needs to be increased… this is done by increasing air flow across the radiator or increasing the surface area of the radiator.

This is likely why the OEM radiator works so well, Chrysler engineers said “oh crap we designed ourselves into a corner, we didn’t design in enough space for a proper radiator”, so engineer B says, we’ll with this design radiator, we can eek out a bit more capacity … aftermarket junk misses the finite details, as we see here.

I am saving my pennies for a all aluminum, fully welded, 2 1.25” row American made radiator. This should increase cooling capacity by 50%. I need to inquire about the fins per inch and find out if the fins are serrated, both factor in heat rejection.

I think the rule of thumb is each subsequent row in a radiator is only half as effective and the one before it.
 
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psrivats

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I've always understood sintered parts to be pressed into a mold and then heated up to bond the particles in place. The parts always have a distinct look that is very smooth but porous. The bubble stones in aquariums are typically sintered as are lots of fuel filters. I got confused by the just dumping in of the metal powder around a mandrel.

I found a good video on YouTube.


Seems there are several ways to do it .. I'm fascinated.

Screenshot_20220813_104511.jpg
 
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TexasTJ2004

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The only thing running without will do is lower the operating temp of the engine IF you have enough capacity in the system to over cool it and the TJ actually does in stock form.

My main reason for running w/o a thermostat was to make the flushes to happen faster. With thermostat I would have to wait till the engine is hot, then wait till engine is cold and only then drain the block. Without the thermostat this cycle worked really fast.
 
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TexasTJ2004

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Engineer to engineer … you forget to include “Duty Cycle” in your thought process … the thermostats job isn’t to wait to get to its set point and stay open. It should be modulating flow through the radiator …

It seems that on our Jeeps the cooling system/thermostat is running wide open once it’s warmed up.

In my experience with classic cars and true analog gauges and much better designed cooling systems. A thermostat change WILL in fact lower the engines operating temperature.

To get super technical, not only does a 195 degree thermostat offer lubrication and wear advantages, also the temperature differential between the coolant and the atmosphere is greater allowing the cooling system to move more energy out of the coolant.

So, I do not believe a thermostat should be part of any sort of “repair”, rather our cooling system capacity needs to be increased… this is done by increasing air flow across the radiator or increasing the surface area of the radiator.

This is likely why the OEM radiator works so well, Chrysler engineers said “oh crap we designed ourselves into a corner, we didn’t design in enough space for a proper radiator”, so engineer B says, we’ll with this design radiator, we can eek out a bit more capacity … aftermarket junk misses the finite details, as we see here.

I am saving my pennies for a all aluminum, fully welded, 2 1.25” row American made radiator. This should increase cooling capacity by 50%. I need to inquire about the fins per inch and find out if the fins are serrated, both factor in heat rejection.

I think the rule of thumb is each subsequent row in a radiator is only half as effective and the one before it.

Our thermostats don’t have any defined duty Cycle AFAIK. They open at 195F and close somewhere at the same neighborhood.
Let’s assume that you have super effective radiator with super effective fan. In this case thermostat will opening and closing instantly. Now let’s assume that fan and radiator suck and can barely keep the coolant at 220F. In this case thermostat will
Simply never close.
Thermostats goal is to keep the engine running at 200/210F, which are operational temperatures for the engine, so if it needs to stay open to keep the engine in this area if will stay open forever.
 
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TexasTJ2004

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To be an engineer there should be a prerequisite as a mechanic which I am a master mechanic! So cool. Have you checked you head? For cracks if you have done everything and all is in spec I would look else where for the issue. Even as simple as a bubble of air. I’ve installed a barbed fitting on upper hose with a bleed screw. Works great.

The only prerequisites to get into university were the grades in physics and math, and some more exams.
But I did take classes in thermodynamics, where I learned that thermal, mechanical and electrical cables circles work the same, and one can be translated into another.
After all the flushes I did, I performed the exhaust in coolant detection test, to check whether gases and coolant mix (head gasket problem usually). I have also performed the positive pressure test, to detect leaks from the cooling system (13PSI is is the pressure that I have generated, and verified that it didn’t drop over multiple hours.
I am running autozone radiator, which does not leak, but it’s cooling capacity seems to be slightly weaker than what TJ needs, and it can be observed only in full AC, plus 95F+ ambient and idle.
 

Larry221

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The only prerequisites to get into university were the grades in physics and math, and some more exams.
But I did take classes in thermodynamics, where I learned that thermal, mechanical and electrical cables circles work the same, and one can be translated into another.
After all the flushes I did, I performed the exhaust in coolant detection test, to check whether gases and coolant mix (head gasket problem usually). I have also performed the positive pressure test, to detect leaks from the cooling system (13PSI is is the pressure that I have generated, and verified that it didn’t drop over multiple hours.
I am running autozone radiator, which does not leak, but it’s cooling capacity seems to be slightly weaker than what TJ needs, and it can be observed only in full AC, plus 95F+ ambient and idle.

A stock replacement radiator should cool just as well as an OEM. If you are in heat often. Why not run a 3 core aluminum radiator with a high CFM electric fan, wired auto/on-high. Super cool additive with the 195* thermostat you should be around 210 I don’t see how it wouldn’t be. Flush is reallly well ?? Like for a day and I’m not kidding I ran my hose for 6 hours lol.
 

mrblaine

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A stock replacement radiator should cool just as well as an OEM.
Based on what logic? The big challenge with the TJ in hot climates is finding a radiator that cools as good as OEM. The instant we find one, we'll never buy another Mopar.
If you are in heat often. Why not run a 3 core aluminum radiator
Why don't you know that radiators only have one core with a number of rows of tubes, 1 row, 2 row, 3 row, etc.?
with a high CFM electric fan, wired auto/on-high.
Mainly because it is very difficult to find a high CFM fan with a higher output than the OEM mechanical fan.
Super cool additive with the 195* thermostat you should be around 210 I don’t see how it wouldn’t be. Flush is reallly well ?? Like for a day and I’m not kidding I ran my hose for 6 hours lol.
No
 
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TexasTJ2004

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A stock replacement radiator should cool just as well as an OEM. If you are in heat often. Why not run a 3 core aluminum radiator with a high CFM electric fan, wired auto/on-high. Super cool additive with the 195* thermostat you should be around 210 I don’t see how it wouldn’t be. Flush is reallly well ?? Like for a day and I’m not kidding I ran my hose for 6 hours lol.

I did flush (BlueDevil, Prestone, Thermocure) multiple times. I did drain the block like at least 5 times for in total. Verified that the engine and the radiator is now clean. Saved the before and pictures for the sake of history

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9BE55711-C2D8-41F1-821B-AF13B196F2BC.jpeg


2B53DFC8-D8F0-4AE3-BCB7-1D1CFC0D776F.jpeg


FC68FA00-56E5-4A2C-809C-0D1A583B39E4.jpeg
 
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TexasTJ2004

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Why not run a 3 core aluminum radiator with a high CFM electric fan, wired auto/on-high.

I do not want to run electric.
The main reason to go electric is to save gas and have less noise. I am not concerned too much with the gas consumption or with noise.
Electric fan that will be as powerful as the mechanical one will create a load on the alternator, wiring, fuses and what not. If anything fails in this circuit, you go straight into overheat zone.
Mechanical fans are far more reliable in general, and you don’t risk loosing your cooling system because of one fuse.
 

freedom_in_4low

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Engineer to engineer … you forget to include “Duty Cycle” in your thought process … the thermostats job isn’t to wait to get to its set point and stay open. It should be modulating flow through the radiator …

It seems that on our Jeeps the cooling system/thermostat is running wide open once it’s warmed up.

In my experience with classic cars and true analog gauges and much better designed cooling systems. A thermostat change WILL in fact lower the engines operating temperature.

To get super technical, not only does a 195 degree thermostat offer lubrication and wear advantages, also the temperature differential between the coolant and the atmosphere is greater allowing the cooling system to move more energy out of the coolant.

So, I do not believe a thermostat should be part of any sort of “repair”, rather our cooling system capacity needs to be increased… this is done by increasing air flow across the radiator or increasing the surface area of the radiator.

This is likely why the OEM radiator works so well, Chrysler engineers said “oh crap we designed ourselves into a corner, we didn’t design in enough space for a proper radiator”, so engineer B says, we’ll with this design radiator, we can eek out a bit more capacity … aftermarket junk misses the finite details, as we see here.

I am saving my pennies for a all aluminum, fully welded, 2 1.25” row American made radiator. This should increase cooling capacity by 50%. I need to inquire about the fins per inch and find out if the fins are serrated, both factor in heat rejection.

I think the rule of thumb is each subsequent row in a radiator is only half as effective and the one before it.

The thermostat does modulate in most normal conditions. If it's 85 degrees or less outside, mine mostly hovers in the 190s. Even if it's 100 outside I can idle all day at 194 as long as I don't turn the AC on. I can even log it during initial warmup and see the ECT drop 3-4 degrees as the thermostat opens and dumps a radiator full of ambient coolant into the block, and then it gradually climbs back up and stabilizes.

The thermostat modulates when (195 - inlet air temp) provides for more heat rejected to the air than the engine is adding to the coolant. Once the inlet air temp rises or the load increases enough that more differential is required, the thermostat is no longer in control or of any consequence.

So, you install a 180 thermostat, sure it'll reduce your operating temp when it's mild or cold outside and you'll see the needle resting a little farther to the left, but once you hit that 100 degree day it's going to wind up right back at 210+ just like it does with the 195.
 
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Ericshere03

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The thermostat does modulate in most normal conditions. If it's 85 degrees or less outside, mine mostly hovers in the 190s. Even if it's 100 outside I can idle all day at 194 as long as I don't turn the AC on. I can even log it during initial warmup and see the ECT drop 3-4 degrees as the thermostat opens and dumps a radiator full of ambient coolant into the block, and then it gradually climbs back up and stabilizes.

The thermostat modulates when (195 - inlet air temp) provides for more heat rejected to the air than the engine is adding to the coolant. Once the inlet air temp rises or the load increases enough that more differential is required, the thermostat is no longer in control or of any consequence.

So, you install a 180 thermostat, sure it'll reduce your operating temp when it's mild or cold outside and you'll see the needle resting a little farther to the left, but once you hit that 100 degree day it's going to wind up right back at 210+ just like it does with the 195.

I totally agree, and that’s sort of my point. Our systems are to taxed that thermostats are not even part of the equation for operating temperature. Our rigs blow past the thermostat temperature and the cooling system is all in trying to keep cool.

In other words, the ONLY ONLY ONLY true fix for or Jeeps is a good radiator, hence why some on this forum are critical about using Mopar, they’re designed for the vehicle at hand, not a generic core, THEY WORK! Otherwise we didn’t have very good options.
 

freedom_in_4low

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I totally agree, and that’s sort of my point. Our systems are to taxed that thermostats are not even part of the equation for operating temperature. Our rigs blow past the thermostat temperature and the cooling system is all in trying to keep cool.

In other words, the ONLY ONLY ONLY true fix for or Jeeps is a good radiator, hence why some on this forum are critical about using Mopar, they’re designed for the vehicle at hand, not a generic core, THEY WORK! Otherwise we didn’t have very good options.

I admittedly haven't gotten as deep into any cooling system as I have the TJ, so I don't know how typical it is to go 15-25deg past the thermostat setting. I've also never pushed one as hard as I push the TJ, by the time I fit it with a set of 75 pound tires, put a winch in front of the radiator, run AC on max with no windows just to get that occasional wisp of cold air that didn't get whipped away in the wind, etc.
 
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TexasTJ2004

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I totally agree, and that’s sort of my point. Our systems are to taxed that thermostats are not even part of the equation for operating temperature. Our rigs blow past the thermostat temperature and the cooling system is all in trying to keep cool.

In other words, the ONLY ONLY ONLY true fix for or Jeeps is a good radiator, hence why some on this forum are critical about using Mopar, they’re designed for the vehicle at hand, not a generic core, THEY WORK! Otherwise we didn’t have very good options.

You have 4 variables:
- Radiators efficiency in dissipating heat
- Coolant
- Airflow (mainly depends on fan in idle, but not when you actually drive)
- water pump that pushes the volume of coolant

In the coolant area you cannot really change a lot.
Water Pump is already good enough. Could be stronger, but without increasing airflow or better radiator it is pointless.
You can increase the airflow by putting more powerful electric fan. But, then you need better alternator, you take a risk of this failing and getting stuck w/o cooling if anything goes wrong.
I think that I will go towards hybrid approach, with small auxiliary radiator (large heater core) taking the hoot coolant from heater line and cooling it with electric. This way, if the electric fails, you still have the mechanical fan. The small additional fan should cover for hot idle.

Even the crappy autozone radiator works fine while I am driving in Texas heat with AC on. But the auxiliary will help in hot idle with AC on, where it is challenging for existing cooling setup
 

Ericshere03

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Just add an Auxiliary radiator plumbed to the heater hoses and be done with it.

I have been do this for over 50 years.

You can fit it behind the grill.

He is a CJ3 heater core, $35 from Rock Auto,

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View attachment 350902

That’s an idea … never thought of that … I have however thought of an OIL cooler mounted ahead of the radiator, which could/should offload some of the burden from the radiator.

Actually, your idea is also pretty cool. Too bad you can’t fashion an inline thermostat set to 205 (yes they make ‘em). With the oil cooler idea i mentioned, they do make bypassing thermostats. Basically the oil circuit would bypass until a certain temperature then the oil would pass through the heat exchanger …
 
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TexasTJ2004

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That’s an idea … never thought of that … I have however thought of an OIL cooler mounted ahead of the radiator, which could/should offload some of the burden from the radiator.

Actually, your idea is also pretty cool. Too bad you can’t fashion an inline thermostat set to 205 (yes they make ‘em). With the oil cooler idea i mentioned, they do make bypassing thermostats. Basically the oil circuit would bypass until a certain temperature then the oil would pass through the heat exchanger …

I mentioned above in my post that:
I think that I will go towards hybrid approach, with small auxiliary radiator (large heater core) taking the hoot coolant from heater line and cooling it with electric. This way, if the electric fails, you still have the mechanical fan. The small additional fan should cover for hot idle.

I will find an inline thermostat, or worst case I would do a simple switch that works based on AC, if AC is on the fan will be on
 

mrblaine

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I mentioned above in my post that:
I think that I will go towards hybrid approach, with small auxiliary radiator (large heater core) taking the hoot coolant from heater line and cooling it with electric. This way, if the electric fails, you still have the mechanical fan. The small additional fan should cover for hot idle.

I will find an inline thermostat, or worst case I would do a simple switch that works based on AC, if AC is on the fan will be on

I might be inclined to add a bit of complexity but do so with an eye on overall improvement. Tap into the heater hose with a temp or switch controlled valve(s) that route the coolant through the small aux radiator but at the same time stops the coolant from circulating full time in the heater core. That would cool down the inside of the HVAC box and add additional capacity out in the air flow (electrical or otherwise).
 
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TexasTJ2004

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I might be inclined to add a bit of complexity but do so with an eye on overall improvement. Tap into the heater hose with a temp or switch controlled valve(s) that route the coolant through the small aux radiator but at the same time stops the coolant from circulating full time in the heater core. That would cool down the inside of the HVAC box and add additional capacity out in the air flow (electrical or otherwise).

I was initially thinking about simple mechanical valve for hot water, which should work nicely at 240F. Basically manually switch between aux radiator and heater core. Like in hot summer month put it to aux radiator, but after than switch to heater core like in October. However, given that I am planning to have the aux radiator in the area w/o natural airflow, I think that I might just keep them serial, as I don’t have want stale fluid inside anything for too much time. I will have to perform measurements to see how it ends up.
My motivation is precisely to decrease excessive heat in the HVAC box, so AC can work little less hard.
I bought this YJ heater core and 6 inch fan, for which I need to build a small frame (similar to what Derale cooler for 42RLE), and add a thermostat for the fan to activate at around ~200F ish,
The location of the aux unit will be in the back, under the tab. There a place under the tub, close to the where the ebrake cables are, where it will fit perfectly. This way it takes the heat out of engine Bay Area, and does not have negative impact on the airflow to the main radiator.
The sole purpose of this aux radiator is to help with hot idle, or very slow stop and go traffic, this is why i want to put it far from engine bay.

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