[FastReligion]

I have built "oversized" CVT Pans that have added 4 quarts of extra fluid, along with a rear mounted pump and 12"x18" CVT cooler with a fan (On Insane Juke). It did not reduce high speed CVT temps enough to prevent limp mode after hard pulls at 267hp on a big turbo.

At a certain point the internals wear out and cause the cvt to over-heat no matter the size cooler. IF you run too large a cooler and your CVT is healthy, you can actually over-cool the CVT fluid and cause the car to think the CVT is not warmed up yet which will change how the CVT acts.

A CVT cooler is just a way to slow the progression of the CVT deterioration, it will not prevent it outright. For example, my friend Angela started having CVT limp mode after 1-1:30 hours of driving, so she came to me and I installed a cooler, told her it was band-aide to buy her more time. 3-4 months later in the dead of winter she calls me and says its doing it again. We replace the CVT, keep the cooler on there, and for the past 3 years has not had a problem.

On my first Juke 5-6 years ago, I put a MASSIVE CVT cooler on it to do some testing when the CVT had 80k miles on it. It started acting funny. CVT levels where okay, but i logged the CVT temps via consult and saw that the CVT fluid temp was getting just a hair over ambient air temp when on the highway, it was cooling too much. Removed the large cooler and installed the one I currently sell, and never had an issue, I sold that car at 130k miles with full bolts ons and daily beatings.

Juke CVTs all fail. It is not a matter of IF it is a matter of when. Some fail spectacularly, like the one on my Nismo that Just got stuck in a high gear ratio, some slowly die by wearing of the internals to where friction heat just happens. I tell everyone who is looking to buy one of these cars this: Put aside $100 a month til you have $3000 saved up, then WHEN the CVT dies, your ready to toss a new one in.

 

[FastReligion]

I was trying to make a product to sell, and thermostatic by-passes ad a LOT to the cost of the system and complexity. Not everyone knows how to tell of one is working right or not. So It had to be simple. You also have to deal with air at that point too. When you shut off a CVT the fluid will drain out the hoses and back into the CVT if the cooler is mounted above the adapter. This is fine when you just start the car back up, as the CVT self bleeds in a few seconds, and your not driving at that point. Now, if your driving the car and the thermostat opens to allow CVT fluid into the cooler, the CVT now has to burp that air in the cooler while it is already moving, which could cause aeration to occur in the fluid, making it more likely the CVT pickup will get bubbles in it and cause issues. Also: Shocking the CVT with ambient air temp fluid on the initial opening of that thermostat is bad too, the internal temp sensor for the CVT could see a dramatic drop in CVT fluid for a second and trip a code or limp mode, thinking something is wrong. You want it all to heat up and level off organically. There is a reason almost no affordable OEM's use thermostatic systems in regards to oil or hydraulics, too many potential issues. You jsut have to size the cooler to maintain a set temp in set circumstances.

At 150miles on the oem cvt, that CVT is just about done. Your lucky it has lasted that long. Highway driving is what kills a CVT. its a long duration of continued torque. Thats why most people get CVT limp mode on the highway, and not some back road. The CVT makes the most heat on the highway.

On the Insane juke I ran a self-priming pump designed for oil with a thermostatic switch with two lines directly into the modified CVT pan. IT was both overkill, and never did what it was meant to do as mentioned above. Your adding a lot of complications with a system like that.

All my jukes, my current one included, just use the OEM 4 barb beehive system. Ive sold hundreds of them, installed dozens of them, and never had any issues.

 

[FastReligion]

old fluid heats up faster and loses its viscosity faster, and at that many mileage, wear is causing it too.
That cooler is WAY too big, on a fresh CVT that will potentially cause CVT temp issues.

 

[FastReligion]

it comes down to the flow rate, the fluid flows fairly slow, and cooler like that can cause it to flow even slower, which means more time to cool off, which is the point. Thats why i run tube and fin, it does not obstruct flow at all, so the fluid can pass through like it normally would in the oem cooler available internationally. But we are stuck with what we are stuck with in regards to the CVT. With all the CVt testing ive done i have found age means heat, old fluid means heat. no cooler will fix that.

 

[FastReligion]

I only ever install OEM reman units. They come with a built in warranty. And that one in the photo is a V2. you can tell from how the front of it looks.

 

[FastReligion]

where would I get a OEM reman? and what do those cost?

the dealership. About $2700.

 

[FastReligion]

No, most CVT's in the Juke are actually over-filled from the factory, theres dozens of posts about it. Make sure you checking the dipstick when CVT fluid temp is ~114F, otherwise it will not read exact (According to FSM) The engine must also be on when checking or you will get a false full reading. I am telling you its the CVT being bad. If the cooler is not getting any flow, you may have a kinked line, the cooler is clogged, or the filter element behind the beehive was damaged and has caused one of the two other issues. The CVT fluid that goes into the beehive has already passed through the CVT itself, so if there was NO flow, the car would not be moving.

 

[FastReligion]

whining is just a symptom, hell, healthy CVT's whine. Just because you dont have a runny nose, does that mean you dont have the flu? Overheating with a cooler means the CVT is bad...cant really say it any other way... As for behaving like a stock beehive, yes, it would if the system where clogged only in the cooler itself. Which would lead me back to saying theres and issue with the cooler or lines.

You have a CVT that overheats. That's already saying it needs to be replaced...
Adding a cooler to a CVT that already overheats just buys you a few thousand miles...
You have a CVT cooler that works inconsistently, that tells me the cooler design is not working.

These are things I have already said. Best of luck to you!

 

[FastReligion]

it should flow through it all the time. Again, Ive installed dozens of CVT coolers, and they are always warm on the face. Ive tested 5 or 6 different set ups, all of them hot across the face.

Nissan is the only place you should ever source a transmission from. You know they used oem parts to rebuild them, and you get a warranty with it.

 

[FastReligion]

Aeration and cavitation is happening because of fluid overfill, don't overfill or overheat and it won't be a problem. The size of oil cooler you would need to dissipate the heat would need to be very large. It's easier to make a more efficient oil/water heat exchanger that uses high water flow rates, to make the exchange with the radiator. I'll be using a Laminova oil/water heat exchanger mounted at the base of the radiator with radiator coolant flow running thru the core, then a couple of CVT oil feed lines coming off a custom oil filter/thermostat adapter mount going in the stock beehive cooler location. The cvt vane oil pump will drive the necessary flow without the need for an external pump. This has enough heat exchange capacity to keep the CVT oil around 98-100 *C if the coolant is running at 85*C, even at power levels past 330 h.p. The thermostat then bypassing the cooler when it's not needed. IMHO all these other external oil coolers are a waste of time, the CVT thermal heat dissipation levels are massive at full power, almost equal to the engine's waste heat thru the cooling system.

So, your saying all the people who have had their overheating CVT helped by installing a cooler, including the OEM nissan one are wasting their time? Sorry, but the real world testing by hundreds of people and the data myself and dozens of other people have accumulated sort of prove they work. Transmission coolers are used on all kinds of transmissions. The beehive is too small to be able to transfer heat effectively using coolant. In fact, according to diagnostics I did at nissan, the beehive is actually there to help stabilize cvt fluid temps, but will not prevent the temp from rising as milage increases. On the rogue for instance: Older ones came with the Jukes style beehive, and for CVT overheating NISSAN had us install a OEM cooler as a "fix" that was basically the cvt cooler everyone installs on their jukes. As for 330 hp, no cvt Juke will ever see that power level, so no one can confirm anything about that heat. I can confirm that at the CVT limit of 267ish hp the size cooler you need with extra fluid to help maintain a good temp during WOT pulls is very large. Your system you are making osunds interesting, ad more than likely will maintain decent cvt temps, but as the CVT ages, there is nothing you can do to prevent it from eventually failing in one of several ways.

 

[FastReligion]

99.99% of people do not track their jukes. So all the R and D being discussed is for a road car to prolong life. I would never ever waste my time making a CVT cooler for a race track. Lars Wolfe tried for years and finally just did a six speed swap, it was cheaper and easier than re-engineering a CVT.

The OP definitely is not tracking his car, so all conversation in this thread is about a road car, and problem/solutions associated with that.

I am excited to see what you can accomplish with a more sophisticated system, don't get me wrong, but the applications are apples and oranges for what you are trying to accomplish. There is a proven system available in a dozen places online to help the OP.

I would love to see your designs for your cooler, it sounds like it would be a blast to make, and i hope thats how it turns out for you.