Anyone with CVT experience?

Automotive
#1

I just pulled my 2012 sentra cvt apart for the 3rd time trying to fix this trans. The first time I discovered a sticking ratio control valve. I polished the steel piston and got it to stick less but ultimately it didn’t fix it, I should have polished the aluminum bore until it stopped sticking completely but it may have cause sealing and pressure issues. So for attempt #2 I ordered a “cleaned and tested” valve body, packed in dirty trans fluid of course. It threw a solenoid code and I over filled it this time without realizing it.

So now on the 3rd attempt, I pulled the replacement valve body and now the ratio valve piston is sticking in it! I’m thinking I’m going to go back to the original valve body and polish the bore of the ratio valve. A replacement at this point would be a week away.

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#2

You could apply fire to the car to see if that improves your situation. I would.

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#3

I feel like we speak the same language.

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#4

1am at Wal-Mart, thinking of ways to polish the bore, I think I came up with the best solution. I used a coat hanger to spin one of the pistons in the bore with mothers mag to lap the cylinder, then install the pristine piston. It worked and I feel better about it than my alternate idea of using mothers mag and a swab from a shotgun cleaning kit.

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#5

Most CVT’s aren’t suppose to be rebuildable outside of the factory I heard.

#6

I know for Nissan, the CVT is considered a sealed assembly and the repair for any internal failure is listed as Replace Transmission Assembly. Honda has the same deal on their CVT, as well as several of their conventional automatics. Not sure about Subaru, Mitsubishi, or Toyota.

#7

Yup. Mitsu is the same.
I would expect the other manufacturers would treat it the same.
For Honda, I was informed that if the chain links didn’t fail in QC there wouldn’t be any expected failures for it’s service life. I don’t think it applies to the other parts of the CVT though.
Have encountered several on first gen non-US Fits/Jazz with fairly low mileage unable to transmit power because of either( depending on how you wanted to look at it ) user ignorance or poor design. The car owners who had the issue, of course, thought it was crap.

#8

When I worked at Honda, we wrote that up as “loose nut between steering wheel and driver seat”.

#9

LOL
Funny, that was the number one cause of almost all traffic accidents that I know of.

P.S. the alternative description was “the nut holding the steering wheel”.

#10

Everything is user serviceable. It’s true nissan doesn’t want to touch the inside of these transmissions, they are however serviced by shops that specialize in it. They are very simple mechanically and a little more complicated electronically. They typically run higher pressures and are pretty sensitive to fluid level.

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#11

Here’s the transmission I’m dealing with. Also check out how much this guy sounds like AvE!

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#12

So far my repair is working. I also think I’m treating a symptom and the real problem is overheated trans fluid that caused the valve body to seize. Nissan adds an extra trans cooler at the first sign of trouble, then replaces the trans if it still has problems. They also claim if you have anything more than 55% glycol for coolant, it can cause overheating issues with the trans fluid. Instead of a trans cooler in the radiator, they used a trans fluid to coolant heat exchanger mounted to the trans.

I had to order a revised heat exchanger that has a inlet and outlet for trans fluid so I can add a real trans cooler.

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#13

That’s a pro reference.


LOL!! I never knew what AvE meant, until I saw the URL.

I’m glad you have it sorted out @Josh_Bishop

#14

I never knew what it meant either.

#15

“want to hear the most annoying wound in the world?”

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#16

How is the transmission now?

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#17

I ended up ordering another valve body, this one worked for a little while but had little hiccups. The valve bodies go for around $100 used, since then, it’s been great.

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#18

Good to know. Glad it worked out

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