Bad CVT?

[JTK]

Originally Posted By: grampi
Originally Posted By: JTK
Grampi, how many miles does she have on it? Sucks either way..

Originally Posted By: Vern_in_IL
I never tow with those CVT's!!!!! They are for light commuter cars only!


My 5800lb Nissan minivan CVT is a ticking time bomb then.


103K


Luckily, I've got warranty for another 5yrs or I hit ~107K. I actually did what I never do and bought an extended warranty with this van.

In regards to the original post, does anyone know what actually fails on CVTs? I don't think I've ever read where the belt or chain itself breaks. The few videos I've seen on youtube or the likes where a shop is actually pulling a broke one apart, they look intact internally.

 

[emg]

Originally Posted By: JTK
In regards to the original post, does anyone know what actually fails on CVTs? I don't think I've ever read where the belt or chain itself breaks.


I'm sure I remember reading about someone who broke the CVT chain on their Forester XT while offroading. I believe it turned out to be a defective part installed in that car.

The biggest single cause, other than just bad design in some CVTs, seems to be use of the wrong fluid, which causes rapid wear until it's unable to transfer power properly any more.

 

[grampi]

The problem ended up not being the CVT at all...apparently a rodent, or rodents had built a nest under the hood and they chewed through wires...time to spray all of her wiring down with pepper spray!

 

[Nick1994]

Originally Posted By: grampi
The problem ended up not being the CVT at all...apparently a rodent, or rodents had built a nest under the hood and they chewed through wires...time to spray all of her wiring down with pepper spray!
And then the next guy who works on the car will scratch his eye afterwards and have a great time.

 

[JTK]

emg- That's the thing. What is it that "wears out" on CVTs? They seem to have less moving parts than a conventional AT with multiple planetary gear sets, bands and clutch packs to control the gear ranges. CVTs still use clutch packs and moving parts obviously for the variator pulley, but finding out what actually goes out on them seems impossible. Youtube videos show a few where valve bodies are being replaced, that's about it. Maybe they are so heavily dependent on electronic control, if one little electrical issue happens, they're rendered useless. That's the case for any modern day AT though. Regardless, I've never seen horrid aftermath pics of a failed CVT. I've seen them first hand with conventional ATs.

Grampi- Thanks for the update on that! Glad to hear it was only chewed wires.

 

[Blang]

From what I understand the ones attached to V6 engines (in Nissans) have trans coolers. The earlier ones attached to 4-cylinders did not. If I understand correctly, when they replace a failed CVT under warranty these days they add a trans cooler. It's worth asking about a trans cooler when you take it in at least. Fluid was getting too hot leading to many untimely CVT failures. I believe all newer Nissan CVT transmissions have coolers now.
Edit: Sorry, I missed the update somehow. I hope my info is still helpful to someone at least.

 

[JTK]

Blang, I know the CVT in my Subaru and Nissan not only have your typical in-radiator cooler, they also have a small CVT fluid heater. A small can shaped heat exchanger that also uses engine coolant.

 

[KingCake]

Originally Posted By: Nick1994
Originally Posted By: grampi
The problem ended up not being the CVT at all...apparently a rodent, or rodents had built a nest under the hood and they chewed through wires...time to spray all of her wiring down with pepper spray!
And then the next guy who works on the car will scratch his eye afterwards and have a great time.


Yeah. You can buy electrical tape with pepper embedded in it to stop chewing. Much better than hosing it down.

 

[grampi]

Originally Posted By: Nick1994
Originally Posted By: grampi
The problem ended up not being the CVT at all...apparently a rodent, or rodents had built a nest under the hood and they chewed through wires...time to spray all of her wiring down with pepper spray!
And then the next guy who works on the car will scratch his eye afterwards and have a great time.


After 5 minutes of thought I realized pepper spray will get rinsed off every time the vehicle is driven in the rain...I'll need to come up with a different rodent deterrent...

 

[grampi]

Originally Posted By: KingCake
Originally Posted By: Nick1994
Originally Posted By: grampi
The problem ended up not being the CVT at all...apparently a rodent, or rodents had built a nest under the hood and they chewed through wires...time to spray all of her wiring down with pepper spray!
And then the next guy who works on the car will scratch his eye afterwards and have a great time.


Yeah. You can buy electrical tape with pepper embedded in it to stop chewing. Much better than hosing it down.


Didn't know that. Who sells it?

 

[zzyzzx]

Originally Posted By: Jimzz

Its mostly Nissan


Subaru CVT's have a pretty bad reputation as well. Just not quite as bad as Nissan's.

 

[Anduril]

Originally Posted By: eljefino
My sister got one of the last Manual tranny Versas! IIRC around 2011/2012. The new model year had only CVTs and the salesmen kept trying to say, the standard transmission *is* an automatic, so we have plenty of standards!

Not true. Wife bought a leftover 2015 with manual trans in February of this year, and they still offer them on the 2017s, but did not have any in stock.

Originally Posted By: JTK
My 5800lb Nissan minivan CVT is a ticking time bomb then.

I'd be willing to bet that it is.

 

[Trav]

Originally Posted By: grampi
The problem ended up not being the CVT at all...apparently a rodent, or rodents had built a nest under the hood and they chewed through wires...time to spray all of her wiring down with pepper spray!


That's great, at least its a fairly easy repair.

 

[Trav]

Originally Posted By: zzyzzx
Originally Posted By: Jimzz

Its mostly Nissan


Subaru CVT's have a pretty bad reputation as well. Just not quite as bad as Nissan's.


Subaru seems to be pretty solid as far as the CVT goes, the dealer I buy parts from has had very few problems with them and no total fails.
That doesn't mean I want to own one, I still don't like the way they feel or drive but that anther story. The Nissan OTOH is like a ticking bomb.

 

[emg]

Originally Posted By: JTK
emg- That's the thing. What is it that "wears out" on CVTs?


I would presume it's the belt and pulleys, and they then start slipping. There's supposed to be a super-thin layer of fluid between them to prevent wear, and if that's not there, then it's going to wear down in all kinds of places. That might also leave debris in the casing that's harder to clean out than to just buy a new one?

My Subaru service manual has instructions for taking the CVT apart and repairing bits and pieces, but I believe they don't do that at the moment--at least for units under warranty--because they want to get them all back to see what has broken in there.

 

[grampi]

Originally Posted By: Trav
Originally Posted By: grampi
The problem ended up not being the CVT at all...apparently a rodent, or rodents had built a nest under the hood and they chewed through wires...time to spray all of her wiring down with pepper spray!


That's great, at least its a fairly easy repair.


Yep, our mechanic said $200-$300 for repairing the wiring...

 

[KrisZ]

The modern CVT "belt" is not really a belt in the traditional sense of the word. It consists of several metal bands that act like a spine, with many steel ribs that attach to the bands and can float. This makes the belt flexible, but made entirely of steel. Also, the belt is not being pulled by the pulleys, but pushed.

The cone shaped pulleys have to constantly apply pressure to the belt and the belt constantly applies pressure to the pulleys trying to separate them. Hydraulic pressure is needed to balance the forces or to overcome them when the pulley geometry needs to change. Hence, once the fluid shears down or there is something wrong with the pump, this tranny will start acting up.

That is why ACT is inherently a weaker design. The acting forces are not perpendicular to the rotation, unlike a traditional clutch/clutch pack arrangement.