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Jeep Too much radiator ?

DaveB

DaveB

Long Jeep Fan
Location
Holladay, Utah
My son's Comanche has had heating issues ever since we put in the stroker motor. I have fixed several things that have helped but he still has problems. Today I did a test on some of the vehicles that call my driveway home and found some interesting results. The test I did was to use an IR temp gauge to see the temperature difference between the top radiator hose and the bottom radiator hose to see how much of a temperature drop was being done by the radiator. The test was done at idle when up to temp. The results I found were as follows: 73 Commando with 5.7 GM engine 60 degrees of cooling, 01 WJ Grand Cherokee 4.7 HO 40-50 degrees, 97 XJ 4.0 20 degrees, old rusty Toyota my son drives 30 degrees and the Comanche 0-5 degrees. So it looks like his radiator isn't working. The odd thing is that it is a Novak V8 conversion radiator that is massive compared to a stock radiator. They claim it should cool almost any motor. Is it too much radiator for his Jeep ? I wouldn't think so but I have to wonder why it isn't performing well. Any thoughts ?
 
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4x4_Welder

Well-Known Member
Location
Twin Falls, ID
It needs a thermostat. I just went through this on my box van, it would get hot on anything resembling a grade, despite having a new engine. Thermal camera showed no difference top to bottom of radiator, and when I fired it up cold I could see coolant flow with the cap off.
Just a couple hours ago I pulled the thermostat housing, and it was empty.
 
Caleb

Caleb

Well-Known Member
Location
Riverton
4x4_Welder said:
It needs a thermostat. I just went through this on my box van, it would get hot on anything resembling a grade, despite having a new engine. Thermal camera showed no difference top to bottom of radiator, and when I fired it up cold I could see coolant flow with the cap off.
Just a couple hours ago I pulled the thermostat housing, and it was empty.
Click to expand...

That’s where I was going as well. The wrong t-stat or even a faulty t-stat will do the same thing.
 
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Omgbecki

Well-Known Member
Location
Ogden
Definitely correct me if I'm wrong but wouldn't this also fall into a problem with the fan? I mean if it's just sitting at idle the fan would be responsible for all the air coming though right? My limited knowledge would hint that not enough air is being pulled through the radiator and such to actually cool the fluid inside it. Maybe the explanation of such a small difference in temperature?
 
DaveB

DaveB

Long Jeep Fan
Location
Holladay, Utah
The engine does have a 195 thermostat and you can see it working as it should with the IR gauge as well as watching the flow with the cap off. The fan could be an issue, The fan clutch seems to be tight enough but with how thick the radiator is I'm not sure it's pulling enough air through. I was going to try a ZJ clutch, which is a common upgrade, but they are too long to get on with the thickness of the radiator. I agree there shouldn't be an issue with too much radiator but I'm at a loss to explain what I'm seeing.
 
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4x4_Welder

Well-Known Member
Location
Twin Falls, ID
Too much radiator would make the returning coolant colder. Does it have a high flow water pump? Have you made sure the radiator isn't clogged? The only way for returning coolant to keep it's heat is if it went through the radiator too fast.
 
DaveB

DaveB

Long Jeep Fan
Location
Holladay, Utah
The engine does have the FlowKooler high flow water pump, high flow thermostat and housing. When it was in my Jeep it had all of the same parts except my radiator was for a V8 CJ and it cooled things fine. The shroud is ok but we did have to modify the mounts for it on the bottom side since the radiator didn't come with tabs for the shroud. The radiator looked clean when we installed it but my son did find it at the junk yard in the back of a Jeep. I think I will do another test with the radiator cap off to make sure the thermostat is doing what it should once the engine is up to temp.
 
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DaveB

DaveB

Long Jeep Fan
Location
Holladay, Utah
I just went and did some testing. I duct taped all around the air shroud and even extended it a bit with some aluminum and it seemed to help the fan pull better but didn't help the temp issue. I did use the IR meter and check different tubes on the radiator and found that some were cooler than others so maybe some blockage. This radiator must be an older Novak design as it has single crossflow tubes that are close to 3 inches wide. The temperature of the tubes from front to back was not consistent. The newer Novak radiators have two tubes not just one monster single tube. The single tube should have more cooling surface but maybe doesn't flow as well ? The thermostat did stay closed to 195 but after that it didn't seem to close most likely because the radiator isn't cooling well enough.
 
DAA

DAA

Well-Known Member
Supporting Member
Location
West Bountiful, UT
Throwing another dart...

From your posts, I'm guessing you do have a wide band on it and do know it's not running lean?

- DAA
 
Spork

Spork

Tin Foil Hat Equipped
Location
Saratoga Springs, UT
Does it overheat when you're driving 55? Or just slow speed or stopped? If it stays cool when you're driving but not when stopped then I don't think you have enough air from the fan
 
DaveB

DaveB

Long Jeep Fan
Location
Holladay, Utah
I do have a wideband and it is running good numbers at all speeds except wide open throttle stays in closed loop running 14.7. The high flow stuff was on my Jeep and had no issues. The temp stays fine when going slow, its going on the freeway or up a hill where you give it more throttle that has issues.
 
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Omgbecki

Well-Known Member
Location
Ogden
I'm not sure it's the high flow pump. According to their info the pump flows normal speed above a certain rpm. Unless I misunderstood it was like 150% at 1800 rpm and down and 100% above 1800 which it's freeway driving. Is the radiator a single core?
 
DaveB

DaveB

Long Jeep Fan
Location
Holladay, Utah
Omgbecki said:
I'm not sure it's the high flow pump. According to their info the pump flows normal speed above a certain rpm. Unless I misunderstood it was like 150% at 1800 rpm and down and 100% above 1800 which it's freeway driving. Is the radiator a single core?
Click to expand...
The radiator is a single core but the core is close to 3 inches wide.
 
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