What is the normal operating temperature for our automatic transmission fluid? For those of you with gauges, what temps are you seeing in city driving, on the highway, and when pushing it? Also, what temperature causes the ECU/TCM to put you in limp mode?

I'm going to install a temperature sensor this weekend and would like know if my temps are normal. The temperature ranges I found in the FSM appear to be most applicable to checking fluid levels.

 

"..the ideal operating temperature for transmission fluid is between 175 and 225 degrees Fahrenheit."
This seems to be agreed upon on the interweb.
If you DO install a Trans Temp Gauge, you should post up a DIY.
I was going to install one on my tC during my Turbo Build, but then I got the Z and what not, but it's simple enough.
I'm sure in some cases, especially hotter areas, those temperatures can easily reach the higher numbers. Spirited driving, accompanied by bumper to bumper traffic, can really bring the heat.

 

Install the temp gauge after your trans cooler in the return line going back to the trans. The above range seems correct. I believe the FSM states that 175 degF is standard operating temperature. My car has twin turbos and the trans fluid has seen temps all the way to 290 degF pushing the car up in the mountains. I shut it down right away and put on a much bigger cooler (and changed ATF when I got home!). With an 11 x 11 x 1.5" cooler on there, temps usually hover in the range of 180-200. Before on the highway, 220-230 would be standard cruising. This is all with FI though. Never had a temp sensor before I went FI.

 

thanks for the info guys

from the info above, it looks like a good rule of thumb is that the trans fluid should operate basically in the same range as engine oil. i have 13" x 6" earl's oil coolers installed for both my trans fluid & engine oil, with 180-200F engine oil temps under most circumstances. i'll report back on the trans fluid temps when i finish up the install this weekend...hopefully there won't be a variance from my engine oil temps.

as for a DIY, most of the heavy lifting is already done. I had Specialty-Z weld a 1/8 NPT port into the trans fluid pan while they were installing a transgo kit, and I installed all of the PLX gauges & modules a few months ago. the AT fluid sensor install will basically be just cracking open that port, dodging the trans fluid, screwing in the sensor, and connecting the sensor lines I have roughed in to my battery compartment. i'll snap some pix of the install if i'm not too covered in AT fluid though

 

My standard temps in the middle of summer (110 degrees) freeway cruising are around 220-240 degrees. The car will go into limp mode at 390 (yes, you read that right) degrees. By that time it's all over, no idea why it would be set so ridiculously high...

 

holy shit, 390!?!?!?!?!?!? that is krazy!

 

I agree. That really seems too high. I thought I was pushing it at 290 F. I did NOT go into limp mode at 290 though. If the matic J can sustain 400 for a few minutes, then perhaps limp mode is ok at that temp - so long as the matic J is replaced afterwards.

 

It can't sustain that high, trust me, at 390 it's over for. Even if the fluid could survive, the transmission most certainly could not, especially not the bands... Limp needs to occur at 290 or 300, not 100 over that... Just make sure you watch it and it's fine. I do a drain/fill every 5k just because i'm OCD about fluids (especially with the temps here). Most agree it's too much, but new fluid will never hurt you unless it hasn't been changed the first 90k miles of it's life... my 2 cents

 

pix of transmission fluid sensor installed are below. i only drove the car for a day before dropping it off at the shop for yet more paint work, but the AT fluid temps were pretty close to the engine oil temps. i'll post up more results when i get the car back next weekend.

looking up and forward at ATF pan and part of the passenger side cat. the front of the car is towards the bottom of the photos

 

bump, so i can answer part of my OP now!

after a 30 minute drive in 85F heat yesterday i got stuck in the worst traffic jam of my life. i took the bay bridge back into SF, but forgot the niners were playing a night game

anyway, tranny temp with my cooler was steady at 150F while cruising towards the city for the previous 30 minutes (its usually 125-150F depending on external temp). when i hit the traffic jam the temps naturally starting inching higher. after 40 minutes and 3 miles (yes, it took 40 minutes to go three f@cking miles!), my tranny oil temp hit 270F which put me into safe/limp mode. fortunately, it happened right as traffic was picking up (10-15 mph, lol) at the foot of the bridge so i limped it across, coasted down to the first exit in SF, and parked at a buddy's place a block from the exit. by the time i parked my tranny temp had already dropped back down (its a long coast down the bridge) and the tranny shifted fine after an immediate restart (saw a better parking spot).

i let the car cool down for 2 more hours then drove home. the car shifted fine and the temps went back to my normal range (150F cruising; 200F in traffic). i'm gonna drain/refill the transmission fluid this week anyway to be safe.

i have an aftermarket radiator so my tranny is 100% cooled by the trans cooler i have mounted up front. i see a lot of stop & go traffic living in the city, so i'm thinking of adding a small fan to help keep temps down when i'm stuck in traffic - which is all to often.

 

Wow, there are other people actually admit to having an automatic.

 

ATF cooler fan (5.25" SPAL puller) installed...should help with temperatures when i'm stuck in traffic. the fan is run off a switch in the cabin with power from the cig lighter (i can't accidentally leave it on), and grounded back at the battery.

 

Hi Chris!

If this doesn't work well enough look into B&M's Hi-Tek Coolers. They only have two models. We use them on all our AT builds. They use Spal fans and have a t-stat switch that automatically turns the fan on at 180 F.

 

^ thanks for the head's up Seb!

i tested the fan out today and it works well. was able to lower my ATF temps at stoplights and its pretty quiet as well (maybe my blower muffled the sound ). it would be cool to have a t-stat on the fan, though, just in case i take my eyes off the ATF fluid temp reading.

 

How big is your trans cooler btw.

 

5 x 16 x 1.5 if I remember correctly

 

Tankx....ima have to go a little larger then what i have on there now.

 

^ wider is better (that's what she said ). i was in LA two weeks ago and saw that Earl's now carries a cooler that's almost as long as the ARC cooler. if I didn't hate messing with AT fluid so much i'd probably swap mine out.

 

Hi, what brand transmission fluid is best for 350z with TT setup ? Heard there's nissan J & S matic, is it the same?

thanks : )

 

You said you had an aftermarket radiator so that your tranny was being cooled solely by an external tranny cooler. I had this problem to at the beginning when I first got turbos. I swapped to a Koyo 52mm radiator that had no inlet/outlet ports for the stock cooling of the tranny fluid. I also had an external tranny cooler.

My car would go into limp mode reaching a tranny temp of around 270-290. I had a gauge to monitor it. I decided to go back to an OEM style radiator that had the inlet and outlet for the tranny cooler. I also hooked up the external cooler along with the route to the OEM radiator.

After that, I never had a problem with tranny temps. I even took the car to the track and did multiple passes on a 90 degree day and it never creeped above 240. A friend and me argue all the time about this. He says the radiator should not provide that much more cooling as it does not circulate through the whole radiator. However, I say look at the proof, I never had a problem after I went back to it. I would suggest trying this, or getting an electric fan added to the cooler you have a long with a good plastic shroud that provides a good path for air to get to it.


S-Matic and J-Matic are the same. For some reason, Nissan decided to change the name. The new one is now S-Matic