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No idea but I believe the factory temp sensor locations are INSIDE the transmission which isn't useful for determining actual tranny fluid temp. You need to install a temperature sensor in the output line from the transmission (before the cooler) so you can read how hot the fluid is that's being pumped directly off the TQ converter. Any readings from the pan or valve body can be 40-100 degrees cooler (depending on load) than actual hot fluid coming off the converter.
I have Nissan Data Scan tool (paid version too) and even it doesn't access these sensors and it seems to know Nissan's systems pretty in-depth. I seem to recall that these data is only available in the TCM, which NDIS doesn't talk to. Some systems, it seems, relay data from their TCMs to the ECU where it is accessible, but Nissan does not.
Any readings from the pan or valve body can be 40-100 degrees cooler (depending on load) than actual hot fluid coming off the converter.
How does Nissan or their Consult system deal with variations like that ? For example, when checking fluid temperature with Consult (per the FSM), it refers to different temperatures for checking the level at. It wouldn't be reliable if it is "off" by as much as you say.
If I can't find reliable temperature method I guess I will just have to trust that the dealer techs did it right at 60K miles when the TC was replaced and just do measured drain and fills. That definitely doesn't make me feel comfortable.
How does Nissan or their Consult system deal with variations like that ? For example, when checking fluid temperature with Consult (per the FSM), it refers to different temperatures for checking the level at. It wouldn't be reliable if it is "off" by as much as you say.
Mostly they "deal with it" by suggesting the 30k mile service interval lol. When you're climbing something like a mountain pass the hot side has SIGNIFICANTLY more heat exchange into the radiator coolant. The engine coolant system has a properly located temp sensor as well as a very large threshold for cooling potential so it's able to handle any extra load presented by the transmission. Tranny return temp is stabilized properly even under significant load but there is still a fairly high degree of breakdown that occurs and thus the service interval becomes mandatory if the vehicle is used in this fashion.
Modern hydraulic oil is incredibly stout even in these kinds of situations, adding a larger external cooler just allows temp to be reduced BELOW engine coolant temperatures in the radiator which in turn lowers the operating temp for the entire transmission. Otherwise the transmission temperature will never drop below engine coolant temperature (measured at the radiator, not the coolant sensor which is on the hot side coolant output at the engine).
OEM equipment is perfectly fine for OEM output but once your engine starts making more torque due to modifications the need for automatic transmission cooling increases beyond what the OEM designed system is built to handle.
Looks like the 370Z is the only Nissan ...other than the Infiniti models Scangauge has listed that have AT Temp PIDs available or have been discovered.
I added an AT air cooler to my GX as US models only have the one in radiator. They put in other markets but not US... It has dropped AT temps around 30-35 degrees so far which puts it safely in the low 170s-180s.
Last edited by treacherous; 06-24-2019 at 08:59 AM.
I mainly wanted this to for easy temp check for AT drain/fill & level check than just guessing at temps.
What I've done is simply drain it and/or check the level after a good, 30+ minute drive at speeds above city or stop-and-go driving. I trust it's as "hot" as it should get under normal conditions with the car's cooling system keeping it from being "too hot". I've checked the level under different circumstances and got varying levels on the dipstick but since I switched to checking it when the car is hot like this - where you have to be careful you don't burn your hand getting the bolt out of the dipstick holder and it feels like you're standing over a hot exhaust fan reaching for it - I've seen consistent (and correct) levels.
What I'll try and do as a test is use an IR temperature gun on the transmission pan and then drain fluid and measure the fluid to see how much it differs.
To me, checking it "hot" is the only option. According to the field service manual, to Nissan, "cold" means 86-122º F. Now, I don't know about you, but when I think of "cold" in regards to a vehicle's fluids, I think of the temperature it's at 10 seconds after you start it up, i.e. basically ambient temperature. The manuals says "warm up engine" and check "before driving". Or, it says drive for 5 minutes in an urban area, i.e. city, stop-and-go driving so frequent gear changing, to get the temperature at 149º F. Not a range, right at 149º F.
Originally Posted by treacherous
How many quarts have you found on a drain? 3-4? I thought I saw someone say they got 5 quarts.
I've changed mine twice and got 3.25 quarts one time and 3.5 quarts the second time. I seem to recall adding less than 1/2 quart later after the first drain but I believe it was in error because of this cold, hot level confusion (on my part). I'm much more confident with the 3.5 quart amount. Someone on the g35 subreddit said he gets 5 quarts which I find very unusual. 4 quarts, maybe as many others seem to get between 3.5 and 4 anyway. An extra quart ? Maybe he jacks the car up at a 45º angle ! I've done it flat one time and on Rhino ramps another time.
He might also be overfilling the pan and simply drain/fill the same amount that comes out.
FSM states that it should be level at the TOP of the HOT hash mark when the fluid temp is 149 degrees F. Since the temp probes are reading pan temp, using an IR gun on the pan is an accurate way to determine this temperature.
A big problem with simply replacing the volume that drains out is the HOT OIL has significant expansion compared to the COLD OIL you will be replacing it with. You should always check the AT fluid level after a drain/fill, an easy way to subtract fluid from the pan if you do accidentally overfill is to just use a gear oil pump and a long section of flexible hose. Stick the hose down the dipstick tube and pump out whatever volume you need subtracted, obviously you want to do this with the motor turned off. Much easier than putting the vehicle back on a lift to access the drain pan bolt.
If you have access to a pit then that's the easier option.
Just trying to determine if hot I can get accurate read on the dipstick. Then I would let vehicle cool overnight in the garage with new bottles nearby. At that point fluid temps should be basically the same without the thermal expansion and then can do a drain, measure and refill.
On my Lexus GX 460 I started out thinking it was complicated but really pretty easy. Drain, measure, add 1/2 quart over drained amount, start vehicle up and at 115 degrees release the overfill plug until fluid goes from a stream to a trickle. Close off... you are at accurate fluid level. This overfill plug has a raised piece into the AT pan and is different from the drain. Pretty much the same on all 2004+ Toyota/Lexus trucks.
06-23-2019, 05:38 PM
