New Radiator, Intersting Temp readings

[Shane06fl]

This past Saturday the new Radiator went in with a new 170 degree T-Stat. All gauges read fine so there is no concern. But on Tuesday, Wednesday and Today after the same 25 mile ride I took some temp readings.
With the truck in drive (E brake on) I used a lazer thermometer that is very accurate. These are averages from 3 days.

Front of engine block right under the heads 187 degrees
Valve covers 171 degrees
T-stat housing 180 degrees
upper rad hose at rad 179 degrees
lower rad hose 167 degrees
Trany input to rad 151 degrees (remember this line has open air for about 4ft)
trany output of rad 165 degrees
Output of trany cooler 149 degrees
Trany body 161 degrees
Oil filter 191 degrees

very consistant reads over the 3 days.
So if you look at the input and outputs of the trany lines at the radiator you see the radiator is heating up the transmission fluid. This is a very good reason to bypass the radiator all together. You can see the cooler is cooling the fluid down 16 degrees. If that the fluid hits the cooler at 151 and cools it 16 degrees that should extend the life of the fluid and transmission.

I am going to test my other truck the same way and see what happens.

[desertruner09]

That's pretty interesting about the tranny fluid actually being heated up by the radiator. I'm assuming the tranny was at operating temp.

I can't see Nissan not noticing that the radiator is actually heating up the fluid. Therefore, I think this may be there for towing purposes. When towing, I'm sure the ATF is quite a bit warmer and then the radiator might help cool it down, slightly.

Either way, very interesting findings! It would be nice to see what those temps are while towing.

[th3sub]

You might want to take into consideration that the truck is sitting still. Which means less air passing through the radiator and trans. cooler. This may affect the over all cooling giving you misleading temps. Note I do say may. I am not an engineer by any means, but I would think that while driving your temperature differentials between the radiator and the trans cooler would be considerably less. Either way it is an interesting find.

[Quartz]

Sorry for the hijack. I have a laser thermometer also. It's a lot of fun to play with. My wife thought I was crazy when I got it but uses it in the kitchen all the time now.

[Shane06fl]

Originally Posted by Quartz

Sorry for the hijack. I have a laser thermometer also. It's a lot of fun to play with. My wife thought I was crazy when I got it but uses it in the kitchen all the time now.

Since you have stated how wonderfull your wife is and she obviously is buying you such cool gadget you may hijack if you like.

[Shane06fl]

Originally Posted by th3sub

You might want to take into consideration that the truck is sitting still. Which means less air passing through the radiator and trans. cooler. This may affect the over all cooling giving you misleading temps. Note I do say may. I am not an engineer by any means, but I would think that while driving your temperature differentials between the radiator and the trans cooler would be considerably less. Either way it is an interesting find.

I pull in the driveway at home, pop the hood and take readings. Readings are done in less than two minutes. Trany in D with fluid flowing. It just doesn't make sense. The radiator is cooling down the engine coolant but teh trany fluid is cooler than the coolant when it hits the radiator. I can see if pulling a heavy load teh trany may heat up to more than the engine coolant and then be cooled down before it hits the cooler. Could be part of how the radiator helps to cool engine coolant.

[54warrior]

Originally Posted by Shane06fl

Could be part of how the radiator helps to cool engine coolant.

hahaha... nice theory... the trans fluid is a heat sink for the antifreeze. Interesting readings none the less.

[NBhunter80]

I pull in the driveway at home, pop the hood and take readings. Readings are done in less than two minutes. Trany in D with fluid flowing. It just doesn't make sense. The radiator is cooling down the engine coolant but teh trany fluid is cooler than the coolant when it hits the radiator. I can see if pulling a heavy load teh trany may heat up to more than the engine coolant and then be cooled down before it hits the cooler. Could be part of how the radiator helps to cool engine coolant.

You will never see the tranny fluid have a higher temp than the radiator unless you are pulling a heavy load up a steep hill. If the Titan is anything like my old diesel with regards to coolant, then having the tranny cooler and the rad linked actually helps bring the tranny fluid up to operating temperature faster. My old truck would automatically reduce power until the tranny fluid came up to operating temperature. I'm sure you are correct that the life of the tranny fluid will be extended if it runs 15 degrees cooler at normal temp; however, you must take into consideration what would happen if your tranny temp stayed lower than the ideal temp for longer due to not being warmed by rad fluid. I'm sure the tranny fluid would be more viscous and not do it's job as well if the temp was significantly below operating temp. So basically if you did seperate them, you would see lower temp under normal conditions, but your tranny temp would rise more under heavy loads, and take alot longer to reach normal operating temp because it does not have the influence of the rad to cool/heat the fluid. This would probably reduce your power for the first 10-20 minutes that you drive your vehicle, and it might cause excess tranny wear because the fluid is not warm enough when you first start driving. This is pure speculation, but it's something that I thought up when noticing exactly what you stated on my old truck.

[Shane06fl]

I am with ya NB. I was shocked when I took the readings. I Am sure it's all in the design and specs of how it should operate. I know the trany needs to be at a certain temp to function correctly just as the engine needs to be at a certain temp to make the right power.

[Learjet]

your truck was designed to operate at a certain temp for many reasons, why do you want to change that?

[layer1]

Originally Posted by Quartz

Sorry for the hijack. I have a laser thermometer also. It's a lot of fun to play with. My wife thought I was crazy when I got it but uses it in the kitchen all the time now.

Sounds like she took your toy away.