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@Kucifer is referring to this an an issue with a 2013...

Yep, I think I'll just keep the bypass to be safe. My truck (07) had the transmission destroyed and swapped and had a new radiator installed (all at same time). I don't wanted another $5000 bill, thanks.
 

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I know I already gave you a "Thanks" but I also wanted to give you props for your very informative post. You not only provided a great explaination but you also included pics so that people that have not heard of the issue can follow along and then to finish it all off, you included some links to others who have had the issues. Your post is one of the most compreshensive ones I have seen and I hope others follow to start and make things a lot easier for others when they are searching.
 

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Yep, I think I'll just keep the bypass to be safe. My truck (07) had the transmission destroyed and swapped and had a new radiator installed (all at same time). I don't wanted another $5000 bill, thanks.
I've had mine bypassed for years now .. total peace of mind. I don't tow or haul heavy loads, but I do run some highway trips in the hot summer with no problem. Short trip "warm up" is a joke, because the radiator doesn't even get warm on a short trip, and the small transmission tube running through the radiator would take FOREVER to warm up the tranny fluid ... so, yes, keep it bypassed for years of peace of mind ... (GUARANTEED NO SMOD).
 

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I've had mine bypassed for years now .. total peace of mind. I don't tow or haul heavy loads, but I do run some highway trips in the hot summer with no problem. Short trip "warm up" is a joke, because the radiator doesn't even get warm on a short trip, and the small transmission tube running through the radiator would take FOREVER to warm up the tranny fluid ... so, yes, keep it bypassed for years of peace of mind ... (GUARANTEED NO SMOD).
All depends where you live. Most people that have measured the ATF temps with the bypass show around 160 degrees F. Optimal temps for trans fluid are 175-200 F. and is shouldn't be run below 150 F. If you live in an area that gets really cold in the winter time, the trans fluid may not get over 150 F. unless it is routed through the cooler. Obviously, if one lives in a state like Florida or Arizona, it's not an issue. However, if the person lives in Canada or a state on the northern border, it would be best to replace the radiator and utilize the radiator's integral cooler.
 

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I have a true trans temp guage installed in the trans pressure test port on the side of the case next to the cooler lines. I'm not sure if this port is in the outbound ( hot ) or return ( cooler ) side line, but in the winter I barely see 100 - 105F and summer is usually about 140 - 150F unless towing or climbing hills while wheelin slowly. I haven't tried the bypass as mine is a 2014 but the only time I've ever seen a temp that concerned me was at Washington Jefferson National Park on a very tight low-speed inclined trail that was taxing all four trucks in the convoy. I observed an indicated 210F at that point and we all stopped for a cool-off period to allow the trucks to rest.
 

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I have a true trans temp guage installed in the trans ..... but in the winter I barely see 100 - 105F and summer is usually about 140 - 150F unless towing or climbing hills while wheelin slowly. I haven't tried the bypass .....
You HAVEN'T done the bypass and still showing "cool temps" ... you WANT to stay cool.
I've never heard of a problem with "too cold" transmission fluid temps .... the bottom line is you never want to "burn" your transmission fluid by operating too hot. I've seen thousands of cars / trucks over the years that have been operated "in town, short trips" and "Grandma cars" that never reach "full operating temps", with NEVER a problem with the automatic transmission. You will generate more heat in the tranny fluid inside the torque converter than you will ever get from the measly radiator tube. If you really feel the need for more temp in the fluid, just "power-brake" your tranny for a minute, that'll heat up the fluid, as experienced by RyanD when climbing hills slowly with a steep grade when the ol' torque converter is really working. So, the argument that people can run their trannys "too cold" falls upon my deaf ears.
 

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...... and is shouldn't be run below 150 F ..... utilize the radiator's integral cooler.
Sorry ... don't believe this. Never seen a "short-trip" or "Grandma car" with tranny problems because the fluid didn't get "up to temp". The radiator "integral cooler" is just that, a cooler ... NOT a "warmer upper", and to believe that it will warm up the fluid on short trips or in the cold weather is just false thinking. The engine and radiator coolant don't even get up to temp on short trips, let alone transfer heat through the tiny "radiator transmission cooler". It's the "fluid slippage" inside the torque converter that will generate heat one hundred times more than a measly tube running through a "radiator cooler". The only time you will see tranny damage is if you "burn" the fluid by running too hot, otherwise, you would see millions of "local Grandma cars" with tranny problems ... just doesn't happen.
 

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An interesting write-up. Take what you will from it.
 

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An interesting write-up. Take what you will from it.
LOL ..... don't take your vehicle to McGee Chev-Olds in Peterborough, Ontario for service !!! LOL
 

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Sorry ... don't believe this. Never seen a "short-trip" or "Grandma car" with tranny problems because the fluid didn't get "up to temp". The radiator "integral cooler" is just that, a cooler ... NOT a "warmer upper", and to believe that it will warm up the fluid on short trips or in the cold weather is just false thinking. The engine and radiator coolant don't even get up to temp on short trips, let alone transfer heat through the tiny "radiator transmission cooler". It's the "fluid slippage" inside the torque converter that will generate heat one hundred times more than a measly tube running through a "radiator cooler". The only time you will see tranny damage is if you "burn" the fluid by running too hot, otherwise, you would see millions of "local Grandma cars" with tranny problems ... just doesn't happen.
As a former Nissan Master Tech of 13 years who also used to rebuild Nissan auto trannies before they finally developed a reman program, I think I know a little bit about what I'm talking about. Yes, transmission heats the fluid. Then, your trans fluid goes to the auxiliary air-to-liquid cooler in front of the A/C condenser which cools the fluid. From there, it goes through the integral cooler of the radiator, which is a more efficient cooler because it is liquid-to-liquid. If the transmission fluid is hotter than the engine coolant inside the lower tank of the radiator, the aluminum, integral cooler of the radiator will cool down the trans fluid. If the trans fluid is cooler than the engine coolant inside the lower tank of the radiator, the cooler will warm the fluid; that's just basic thermal dynamics. As I mentioned, the ideal temperature for automatic transmission fluid is 175-200 degrees F., which is perfect because that's typically what the temperature of the engine coolant is inside of the radiator's lower tank. Also, the integral cooler isn't a skinny tube on the 05+ Nissan Frontiers and it's actually pretty big if you ever saw one. Earlier Frontiers could have a finned tube inside the lower tank, which was a problem when a transmission clutch pack would start failing because the fibers would clog the cooler and could cause damage to the replacement transmission due to overheating if the cooler was not properly flushed or the radiator replaced. You mention fluid not getting up to temperature on short trips, but you'd be surprised of how quickly engine coolant starts heating up as soon as the engine is started, especially in an engine with an aluminum block and heads like the VQ40DE because the aluminum transfers the heat much quicker to the coolant than would an engine with cast iron heads and block or aluminum heads and cast iron block. And getting up to temperature is important because the engine oil and trans fluid have to get to 158 degrees F. before it will begin to burn off condensation. Also, keep in mind that viscosity of automatic transmission fluid, just like engine oil, is affected by temperature. In the northern areas of the US and in Canada it's not uncommon to see sub-zero temperatures. Conventional transmission fluid thickens at zero degrees to the point where it won't properly lubricate internal parts and cause slippage, however, synthetic fluids do better. Now, driving the Frontier with the trans fluid consistently below the optimal operating temperature isn't going to make the transmission blow up on you, but it's not good to the transmission long-term health, either. I've attached a pdf of a page that shows more info in regards to trans temperatures.
 

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2004 Nissan Frontier XE KC KA24DE
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During a recent out of town road trip my trans temp gauge ran steady in the 200°-210° range (sensor in pan) and my engine coolant temp in the 195°-200° range. Chuggin along at a good clip most of the time too.
I just love my Uniden R3 and am so glad that laser/lidar speed enforcement isn't a concern in my region as of yet.
 

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REAL curious:
What kind of MPGs do you get at nearly 100 mph?
 

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My 2019 average coolant temp is around 198-203 and trans temp is always around 170 when warm. I’ve never seen the temp get past 185.
Using scan gauge II and had to program the code in to read ATF temps. It actually shows 2 ATF temps. One is always + or - 5-10 degrees of the other. So probably inlet and outlet.

I live in Florida and coolant gets up to temp in maybe 5-7 mins and yes the trans temp even down here in the south still takes maybe 15-20 mins of operation before it levels out
 

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My 2019 average coolant temp is around 198-203 and trans temp is always around 170 when warm. I’ve never seen the temp get past 185.
Using scan gauge II and had to program the code in to read ATF temps. It actually shows 2 ATF temps. One is always + or - 5-10 degrees of the other. So probably inlet and outlet.

I live in Florida and coolant gets up to temp in maybe 5-7 mins and yes the trans temp even down here in the south still takes maybe 15-20 mins of operation before it levels out
What is this scan gauge? Is it something that plugs in or a hard wired gauge?
 
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