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Discussion Starter #1
Anybody else having issues with the aisin transmission pegging hot while going up a hill at low speeds for extended periods of time? Dealership says they can’t replicate or fix it because the truck doesn’t have a dedicated 4x4 fan for drawing air over the radiator at low speeds to cool a transmission. Nissan consumer affairs has been contacted but so far no fix offered.
 

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Need more info...

Is the truck unloaded, carrying cargo, towing a trailer?
What gear are you in?
What speed are you driving?

The only fan you have for drawing air across the transmission cooler is the engine clutch fan. With the previous Jatco transmission, selecting a lower gear would bring up the engine RPM, which in turn increased the RPM of the clutch fan.

With my '07 Titan, I could drive uphill all day long at 45 MPH as long as I kept the transmission in 3rd gear. This was while towing. Your transmission is different, so your results may vary.

Unfortunately, you may have to actively manage the transmission by forcing it into a lower gear.
 

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Discussion Starter #3
Need more info...

Is the truck unloaded, carrying cargo, towing a trailer?
What gear are you in?
What speed are you driving?

The only fan you have for drawing air across the transmission cooler is the engine clutch fan. With the previous Jatco transmission, selecting a lower gear would bring up the engine RPM, which in turn increased the RPM of the clutch fan.

With my '07 Titan, I could drive uphill all day long at 45 MPH as long as I kept the transmission in 3rd gear. This was while towing. Your transmission is different, so your results may vary.

Unfortunately, you may have to actively manage the transmission by forcing it into a lower gear.
All I had in the truck was myself two dogs and a back pack. 4x4 high range 1st gear over a rocky old mining road. 1-2 mph for about an hour. Rpms up to only 2,000. Crawling up this hill that I have taken a 98 dodge Dakota, 2000 f350, and a 2014 Jeep Wrangler up numerous times.
 

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Do it in 4Lo. It will let you get a higher engine RPM with less stress on the transmission.

The newer transmissions may be optimized for MPG. They like to get up in the gears.

Also, make sure you verify the level of the transmission fluid. Even slightly low on fluid, the older Jatco was finicky.
 

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Do it in 4Lo. It will let you get a higher engine RPM with less stress on the transmission.

The newer transmissions may be optimized for MPG. They like to get up in the gears.

Also, make sure you verify the level of the transmission fluid. Even slightly low on fluid, the older Jatco was finicky.
I second checking the fluid..

Somethings not right that Aisin shouldn't be doing that.
I wonder if the fluid cooler has a thermostat...
 

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Discussion Starter #6
Trans fluid was full. Dealership said sometimes they don’t come out of the factory with full fluids to which I replied then you should have caught that before I left the lot and you’ve been doing all the maintenance on it. Had just been in for oil change at 15k mark.
4L might have helped but I’ve never had to go into that in any vehicle going up that hill even when there was mud and snow on it. I wouldn’t think the transmission would over heat in 27 degree weather under those conditions.
 

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I had my '07 transmission overheat in a blizzard while pulling my ATV on a trailer up a small mountain pass. I was doing, at most, 5 MPH, trying to find the next reflective pole to make sure I was still on the road. In that case, I forced the truck to stay in 1st gear and that brought the transmission temperature down. I was in 4Hi at the time.

In your case, don't think of 4Lo as being needed for traction. Think of it as a way to save wear and tear on your transmission. My hunting partner drives an '07 Armada. His would always overheat going up the same hill I went up without any issue. Once I clued him in to the 4Lo trick. there was no more overheating.
 

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Discussion Starter #8
I’m all for trying it. Just seems like I’m pushing the capabilities of the truck beyond what engineers at Nissan claim it can do. Never had a 4x4 without an auxiliary fan to draw air through when you are working the power train at low speed and rpms. Worries me that I will have to use a totally different rig to do what I do because it’s incapable of handling what a 20 year old truck did in 2wd.
 

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My '07 had an auxiliary fan, but it covered maybe 1/6th of the radiator. It came on when the A/C was on or when the internal coolant temperature reached 212° F.

I ended putting in dual Spal e-fans in my Titan. They were turned on when the coolant coming out of the engine reached about 190° F, as I recall. I could have added a switch in the cab to turn the fans on when I thought they needed to come on. That probably would have helped my transmission temps. However, the e-fans pulled far less air than the OEM clutch fan could. If you tow, I recommend against using e-fans.
 

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Discussion Starter #10
I do tow on occasion and so far the hottest the trans has gotten was 3/4 of the way up the temp gauge flat towing 6-7k well under vehicle specs. Very disappointed that $50k truck that’s “off-road” ready really isn’t.
 

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I do tow on occasion and so far the hottest the trans has gotten was 3/4 of the way up the temp gauge flat towing 6-7k well under vehicle specs. Very disappointed that $50k truck that’s “off-road” ready really isn’t.
So the radiator fan clutch on the xd and second gen has its “engagement” electronically controlled.... unlike the older fan clutches that used a heated wire to make the fan operate these new fan clutches are controlled by the ecm allowing infinite control as needed to save load on engine.
It is possible yours is not engaging enough at low speeds to draw ample air over the trans cooler.
The fan clutch went out on my 16’ xd. What happened in my case was it was staying fully engaged all the time even it 40 degree cold air temps. Your issue may be opposite of mine.

A good way to test is stop truck on warm day..leave truck in gear with ac on 60 and blower set high.
If the air starts feeling much warmer after about 30 seconds your fan clutch may be the issue.

One thing Nissan did right on these trucks was the ac. Both my xd and regular titans blow ice cold air at idle even on 100 plus degree days...
 

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Discussion Starter #12
So the radiator fan clutch on the xd and second gen has its “engagement” electronically controlled.... unlike the older fan clutches that used a heated wire to make the fan operate these new fan clutches are controlled by the ecm allowing infinite control as needed to save load on engine.
It is possible yours is not engaging enough at low speeds to draw ample air over the trans cooler.
The fan clutch went out on my 16’ xd. What happened in my case was it was staying fully engaged all the time even it 40 degree cold air temps. Your issue may be opposite of mine.

A good way to test is stop truck on warm day..leave truck in gear with ac on 60 and blower set high.
If the air starts feeling much warmer after about 30 seconds your fan clutch may be the issue.

One thing Nissan did right on these trucks was the ac. Both my xd and regular titans blow ice cold air at idle even on 100 plus degree days...
I do agree with the ac and heater being phenomenal. They just re-flashed The ecm and tcm hopefully this will help fix the issue. The other thing they’re hoping it fixes is my mpg. Fluctuates between 17 in city and 5 on the same road and conditions at the same time of day. No reason why.
 
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