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Discussion Starter · #103 ·
I drove the car around a little more tonight and the check engine light came on today . I used my scanner and it was a code p1126 which is a thermostat code so it finally came on with the thermostat out so I will be putting it back in next week
 

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The p1126 is a good sign. It seems that the original replacement radiator may have been either too small or had a blockage somewhere. The real test will be when you put the thermostat back.
 

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Discussion Starter · #105 ·
Yeah I hope it was just the radiator I will be putting the thermostat back in sometime next weekend and I will let everyone know. The replacement radiator like I said was off Amazon and it was only 5/8 thick and the one I have in it now is 1" 1/4 thick which is almost double the thickness so I am hoping that your right just the radiator
 

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'03 Xterra SE 2WD, 175K
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I tested the new genuine Nissan thermostat today and it works I put a thermometer in the water and it opened at 190°
Thar is the
Well I replaced the radiator top and the oem Nissan thermostat
What's the part # for the new Nissan thermostat you got & where did you order from, a local dealer? I thought the OEM for these is 180 deg. I'd love a 190 deg t-stat for my '03 - it takes forever to warm up in winter, but i haven't found reference to a 190 deg version anywhere.

Also, i'm not suggesting this is part of your original problem, but running withOUT a t-stat can make a vehicle run hotter, as the coolant shoots thru the system too fast for the radiator to cool it down.

Is there any chance one of your radiator hoses is installed without enough slack to let it relax in a fully round unrestricted shape?
 

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Discussion Starter · #107 ·
I don't usually.run any vehicle without a thermostat I am trying what others on here has told me try to eliminate the thermostat causing my problem. As far as where I got the thermostat it was from Nissan. I didn't say the thermostat was a 190° one I was stating that it started opening and my thermometer was reading like 190° roughly
 

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Discussion Starter · #109 ·
I changed the radiator to a thicker one and as of now it seems to be doing ok I will be putting the thermostat back in this week sometime. I am hoping to other radiator was to small or just wasn't enough flow going threw it. Got it from Amazon for less the $100 so probably was junk
 

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2004 Xterra XE 4WD Auto 3.3L NA V6
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... snip ...
Also, i'm not suggesting this is part of your original problem, but running withOUT a t-stat can make a vehicle run hotter, as the coolant shoots thru the system too fast for the radiator to cool it down.
... snip ...
There are 2 camps about that statement, both equally insistent that the engine will run hotter or cooler. Both can't be true. I'm not convinced one way or the other, but if I had to guess, I'd lean toward the cooler side of the fence.

A t-stat controls the flow on 2 circuits, not just to the rad. The part that opens to let coolant flow to the rad does so to help cool the fluid as the engine warms up. The other part of the t-stat that sticks out controls the amount going to the bypass. When fully open, the bypass is closed off; when fully closed, the rad is closed off; when partially open, the 2 circuits are open by varying amounts.

Without a t-stat, both are fully open, so the flow will be split more-or-less evenly.

One question I have about the coolant moving too fast and being less able to absorb heat: What happens when the engine is getting too warm and you shift down one gear to speed up the engine? Every car I've ever driven causes it to cool down, not get hotter. In my experience, moving the coolant slower makes it overheat, not moving it faster.

I'm not calling anyone out. I'm simply asking for a sane and lucid discussion so we can all learn and come away with a better understanding overall.
 

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Discussion Starter · #111 ·
I agree with you Me too , I was always told that removing the thermostat the car would not heat up as it would as if it was in it. Back in the day around here people use to put cardboard in the front of the radiator so the car would warm up because of no thermostat. I would like to know the real answer as well . I would think the car would run alot cooler my self but we will hear from some others.
 

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There are 2 camps about that statement, both equally insistent that the engine will run hotter or cooler. Both can't be true. I'm not convinced one way or the other, but if I had to guess, I'd lean toward the cooler side of the fence.

A t-stat controls the flow on 2 circuits, not just to the rad. The part that opens to let coolant flow to the rad does so to help cool the fluid as the engine warms up. The other part of the t-stat that sticks out controls the amount going to the bypass. When fully open, the bypass is closed off; when fully closed, the rad is closed off; when partially open, the 2 circuits are open by varying amounts.

Without a t-stat, both are fully open, so the flow will be split more-or-less evenly.

One question I have about the coolant moving too fast and being less able to absorb heat: What happens when the engine is getting too warm and you shift down one gear to speed up the engine? Every car I've ever driven causes it to cool down, not get hotter. In my experience, moving the coolant slower makes it overheat, not moving it faster.

I'm not calling anyone out. I'm simply asking for a sane and lucid discussion so we can all learn and come away with a better understanding overall.
In this discussion you have to keep in mind there is a "time" component involved in the transfer of heat or cold from one medium to another. Both in heating and cooling, the ability to remove heat from a fluid [radiator] or air passing over a AC cooling radiator[coil etc] is strongly influenced by the rate at which the coolant or air passes through the cooling device. The heat is transferring from one medium to the next and sufficient transfer is related to the time the two are in contact. Example: If you put a digital thermometer into one of your dashboard cooling outlet ducts and monitor the temperature of the output air, you will find a optimal fan speed that provides you with the lowest/coolest temperature output. Don't assume that placing the fan on high is providing you maximum cooling because you are likely to find it is not. If the warm air is passing over the AC cooling coil too quickly it does not have sufficient to time to remove the maximum amount of heat. I know....blah, blah...blah!
 

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In this discussion you have to keep in mind there is a "time" component involved in the transfer of heat or cold from one medium to another. Both in heating and cooling, the ability to remove heat from a fluid [radiator] or air passing over a AC cooling radiator[coil etc] is strongly influenced by the rate at which the coolant or air passes through the cooling device. The heat is transferring from one medium to the next and sufficient transfer is related to the time the two are in contact. Example: If you put a digital thermometer into one of your dashboard cooling outlet ducts and monitor the temperature of the output air, you will find a optimal fan speed that provides you with the lowest/coolest temperature output. Don't assume that placing the fan on high is providing you maximum cooling because you are likely to find it is not. If the warm air is passing over the AC cooling coil too quickly it does not have sufficient to time to remove the maximum amount of heat. I know....blah, blah...blah!
The warm, outside air passing over the AC coils is not the same as liquid inside the engine being in direct contact with the block. Air is more than 20 times less capable of removing heat than liquid, but we're not fish, so we cool the air. AC also removes humidity through condensation, which affects how well it cools. (I've heard that the figure is around 26, but "over 20" is a reasonably fair approximation.)

If the radiator is properly sized for the engine, then its size should not be an issue, either.

The amount of time the coolant takes to circulate through the engine should be more than sufficient to heat it up enough, so fast or slow water pumps should also not be a factor in determining if it can absorb heat. As with my question above, since the water pump is designed for the engine, if it's doing 4ooo RPM then the pump and cooling system are designed to work acceptably at that rate.

(Edit: Added this paragraph.) Giving it some more thought, I can see that redirecting some of the coolant back into the engine via the bypass would reduce its ability to effectively cool the engine, especially when it's warm or hot out.

What I'm after, now that I've kicked the door open on this subject (sorry for hijacking you, @01Littlejimmy), is actual evidence, not hearsay, myths, or "seems legit". After all, my statements above seem as legit as the next guy's, but I also realize that I don't always get it right.
 

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Yep. As a matter of fact, when I replaced the radiator in my 2003 Normally Aspirated I installed an SC specifically for that reason.
 
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