CVT Transmission Temperature

[CyclingFit]

Hello All - At least 10 years of knowing BITOG is an awesome place, and finally making a post!

Because this seems like a generic question I gave over 10 minutes to the search feature and did not prevail. If the answer exists, it is buried pretty well.

CVT transmission temps vs regular automatics? Are the expectations the same?

I plan to get a 'Scangauge 2 with X-gauge' that will allow me to monitor CVT temps in my 2018 Honda Fit EX w/CVT. About 75% of my driving is at max gross vehicle weight, combined with two bicycles creating wind drag on the back of the car. The drag is more than people would expect since it normally knocks 3-4mpg's off my fuel economy. I had no issues during the 2018 season, but I would also like to know if I am working the car on the edge of acceptable.

Thanks!

 

[Kestas]

I believe CVT transmissions run hotter. I say this because my Nissan Murano is designed with a finned aluminum transmission pan, plus there is an air scoop to direct the air to the transmission pan. I believe the Murano is designed to go into limp mode when the CVT fluid overheats.

 

[StevieC]

Belt type CVT's generally do operate at higher temperatures that I have seen as measured by my scan tool.

My aunt's Nissan Juke would regularly run over 210F oil temperatures with regular driving. This type of CVT depends on super high oil pressure and friction with the steel belt to keep it working properly.
The fluid they use helps to limit the amount of heat generated from this friction as much as possible but has to allow a certain amount in order for the transmission not to slip too much so it can transfer the power.

In comparison other conventional transmissions I have seen will operate with fluid temperatures around 90F - 180F under normal operating conditions depending on the season and the vehicles transmission cooling system setup.

 

[tcp71]

Those temperatures are normal for modern automatics as well. 180-220 are normal for most autos today as well.

 

[Virtus_Probi]

I'm not sure if I can monitor CVT fluid temp with the Torque app...I might give it a shot if I can.

As for carrying bikes, at least yours are in back! I didn't want to put a hitch on my FXT just for bikes and ended up buying a roof mount rack. Talk about wind resistance, and I probably glance up through the sunroof every 20 seconds when there are bikes up there to make sure nothing is going wrong. I ended up having to bring bikes back from the mountains on an unexpectedly windy day once and it was just miserable.
I poked around online looking for a lightweight (preferably aluminum) hitch just for light duty like carrying bikes and such a product didn't seem to exist...I would imagine there might be some liability issue if a buyer tried to do heavy towing and it fell apart. I thought about trying to pull the hitch off my RAV6 in the winter and decided that it wasn't worth it after poking around back there for a while (even though it was a bolt on).

 

[Cujet]

As a general rule, oils have a fairly narrow normal operating range, roughly 160F-240F.. It's not likely that CVT's will operate at a significantly higher temperature than other oil lubricated equipment. Whether they produce significant heat under high load is another question entirely. As is the question of whether internal components get hot "locally".

I recently rented a Subaru Crosstrek and the CVT failed at 2400 miles. It failed going up a long grade at highway speed with the adaptive cruise control on. The RPM was about 4000, and when the vehicle ahead of me pulled over, RPM went up to 5200, as the cruise control tried it's best to achieve 70mph.

We never made 70mph, as the transmission let go, likely due to the highway speeds and high load. I speculate that the chain-belt overheated and failed. My speculation is backed up by multiple Subaru CVT failures.

Note: They tested the CVT in the mountains. But climbing long steep hills at slow speeds is not the same as climbing a long grade at highway speeds, in the summer, with an engine that does not have enough power to achieve the speed limit on that grade.

 

[CyclingFit]

This is all great information. I will for sure be able to get some baseline, empty car, data since the car runs fantastic and only has about 18,000 miles. The high end of the range is my most curious number and it does make since that oils all have a fairly common operating range, as mentioned by Cujet.

Cujet - My driving style is to eliminate the scenario you just referenced with the over revving cruise control... My car has a fake 7 speed paddle shifting system that I LOVE. The cars electronic controls mimic a gearbox and make it a ton of fun to drive. In mountain situations I have used the paddles in an effort to hold RPM's down. My lack of familiarity makes me wonder if that could also create heat.

I'll get the Scangauge2 in the very near future (maybe today at lunch) and I'll start to learn more. I'm hopeful to get more exact 'high limits' in the near future.

Virtus_Probi - I leaned the fuel mileage and driving consequences of bikes on the roof, many-many years ago. On this car I got the most simple hitch I could get and I purposely do not have any trailer wiring. I don't want to have the conversation with the dealer if I am ever questioned about warranty and trailer towing. The only time I have ever taken my car to the dealer I purposely had the rack installed so it would eliminate any questions about what I use the hitch for. The service manager actually complimented my setup.

 

[MolaKule]

Quote
CVT transmission temps vs regular automatics? Are the expectations the same?


Pretty much the same.

If the CVT is mechanically bolted to the engine, as in transverse mounted systems such as seen in the Nissan PathFinder and others, expect the temps to spike until the lube cools down.

Another thing to keep in mind is that CVT's have relatively small sump capacities.

I recommend changing the fluid initially at 10,000 miles and then 30k intervals thereafter for normal driving practices.

Change the fluid every 15k miles for Severe Service.

 

[The Critic]

Not necessarily.

I was doing a spill and fill on a 2010 Altima last night and I had to get the ATF Fluid Temp Count between 158-161 in order to set the fluid level correctly (per the TSB). During in-town driving, trans temps stayed in the 140s. It took over 20 min of aggressive highway driving before temps would read in the 150's.

 

[CR94]

The fact that CVTs, like conventional automatics, require cooling provisions says something about their (in)efficiency.

 

[Cujet]

Originally Posted by The Critic
Not necessarily.

I was doing a spill and fill on a 2010 Altima last night and I had to get the ATF Fluid Temp Count between 158-161 in order to set the fluid level correctly (per the TSB). During in-town driving, trans temps stayed in the 140s. It took over 20 min of aggressive highway driving before temps would read in the 150's.



That's good to know. Does the Altima have a transmission cooler?

 

[The Critic]

Not sure. I think it has your normal heat exchanger.

 

[Cujet]

Originally Posted by CyclingFit
Cujet - My driving style is to eliminate the scenario you just referenced with the over revving cruise control... My car has a fake 7 speed paddle shifting system that I LOVE. The cars electronic controls mimic a gearbox and make it a ton of fun to drive. In mountain situations I have used the paddles in an effort to hold RPM's down. My lack of familiarity makes me wonder if that could also create heat.

I'm truly not sure. I'm not even sure the engineers that design the things know. At best, they refine the designs as troubles pop up.

This much I do know, Crosstrek's have a very high fail rate, some say as high as 14% of the fleet, and highway speeds are often involved. There may be some luck involved too. As some seem to last a very long time. A friend's Murano reached 225K before the engine was run without oil (no fault of his, as the Nissan dealer failed to put oil in the engine). The CVT was always a worry, but in the end, proved to be trouble free.

 

[2dogs]

I'm not sure if I can monitor CVT fluid temp with the Torque app...I might give it a shot if I can.

I am able to monitor my Forester's CVT temp with an app called Active OBD. Temps appear to be in the 200 degree range. I guess it would vary based on ambient temperature and type of driving.

 

[CyclingFit]

The following is not scientific. The following is only as accurate as I was hopeful to hear when I first posed the question. Instead of completely disappearing into the unknown.... I thought I should bring back some data.

I ended up with the Scangauge 2 and the ability to monitor CVT temps. 7+ months have taught me....

The car does have a CVT warmer. Basically a heat exchanger between the engine and CVT. This will bring up CVT temps quicker for fuel economy and my best guess is that once it tries to go over the engine coolant temp, then you could consider it a CVT cooler. That is very loosely said, but the truth is that it works both ways.

So, about the temps...

Southern Indiana Winter, under 20 degrees: The trans almost never gets over 100 degrees (f) with my driving and short trips under 15 minutes. From there the temps creep up very slowly and I believe interstate cruising was around 150 degrees. No interstate hills in Southern Indiana.

Spring and temps into the low 70's: CVT acts just like the winter, but add about 20 degrees. It warms up sooner of course, but not a lot sooner.

Summer 85-100 degrees: The CVT warms up incredibly quickly. I know it helps that it's already warmer to start with... With the car running between 185-190, the CVT is usually 195-205. This is interstate at 75mph. This year has been different and we have not had the car loaded down with stuff, which means just a us and maybe a backpack or three..

At about 27,000 miles on the car, I plan to change the CVT fluid at some point this year. Temperature wise, I feel like interstate driving is where it sees the hottest temps and most of my driving is interstate.

 

[JTK]

The late model Subaru and Nissan vehicles I've owned with CVTs all had fluid heaters/coolers on them. In terms of them running hotter than a present day conventional AT, I'm not sure about that. The ZF 8spd (8hp45) in my 2017 Ram also has a fluid heater/cooler that tries to maintain a 185F ATF temp. I've seen it exceed 200F in 90F+ ambient temps. Apparently ZF only sees temps in excess of 240F a problem.

 

[CyclingFit]

Originally Posted by JTK
The late model Subaru and Nissan vehicles I've owned with CVTs all had fluid heaters/coolers on them. In terms of them running hotter than a present day conventional AT, I'm not sure about that. The ZF 8spd (8hp45) in my 2017 Ram also has a fluid heater/cooler that tries to maintain a 185F ATF temp. I've seen it exceed 200F in 90F+ ambient temps. Apparently ZF only sees temps in excess of 240F a problem.


Previous posts and your experience you just shared, it seems that engine and trans temps being the same or trans just a bit warmer, is very common on modern vehicles.

Now I am wondering the best way to maximize longevity since my best guess is that Honda tried to find a tipping point between fuel economy and probably lasting two warranty periods.

Seems like I just cannot go wrong with 30,000 fluid changes. I would love try a different brand fluid, but it terrifies me! LOL.

 

[bbhero]

Originally Posted by Cujet
Originally Posted by CyclingFit
Cujet - My driving style is to eliminate the scenario you just referenced with the over revving cruise control... My car has a fake 7 speed paddle shifting system that I LOVE. The cars electronic controls mimic a gearbox and make it a ton of fun to drive. In mountain situations I have used the paddles in an effort to hold RPM's down. My lack of familiarity makes me wonder if that could also create heat.

I'm truly not sure. I'm not even sure the engineers that design the things know. At best, they refine the designs as troubles pop up.

This much I do know, Crosstrek's have a very high fail rate, some say as high as 14% of the fleet, and highway speeds are often involved. There may be some luck involved too. As some seem to last a very long time. A friend's Murano reached 225K before the engine was run without oil (no fault of his, as the Nissan dealer failed to put oil in the engine). The CVT was always a worry, but in the end, proved to be trouble free.



276k miles on my VQ 3.5 L CVT car....

No fluid change yet either..

And like you stated... The motor part of the equation matters a lot more than people realize.

 

[CharBaby]

Originally Posted by The Critic
Not necessarily.

I was doing a spill and fill on a 2010 Altima last night and I had to get the ATF Fluid Temp Count between 158-161 in order to set the fluid level correctly (per the TSB). During in-town driving, trans temps stayed in the 140s. It took over 20 min of aggressive highway driving before temps would read in the 150's.


I though the CVT fluid level check needed to be between 98*F-113*F after a D&F.

 

[The Critic]

Originally Posted by Char Baby
Originally Posted by The Critic
Not necessarily.

I was doing a spill and fill on a 2010 Altima last night and I had to get the ATF Fluid Temp Count between 158-161 in order to set the fluid level correctly (per the TSB). During in-town driving, trans temps stayed in the 140s. It took over 20 min of aggressive highway driving before temps would read in the 150's.


I though the CVT fluid level check needed to be between 98*F-113*F after a D&F.

Only on the ones which take NS3.