2019 Nissan Sentra Manual Transmission issue

[Jcornwell101]

I have a 2019 Nissan Sentra S 6spd manual I have owned since 29 miles and it now has 146k.
I have maintained the car per the book in terms of preventative maintenance. Besides
I changed the manual transmission fluid about every 50k or so miles with a nissan MTF TL/JR like the manual says.
I have used redline MTL, Motul 75w80 Motylgear, triax 75w80, and now Nissan MTF 75w85.

I noticed that it was getting towards the end of what I was toward the end of needing to change the triax and towards the end of my 1hr 15 min commute it would grind second no matter what I did. So I tried changing the oil to the Nissan MTF because I found it cheap on amazon and it helped, but did not get any better. So I took my car to AAMCO and they inspected/test drove my car and said that I needed a clutch. So a few days later they showed me my old clutch that I was a hair above the rivet and my throw out bearing was wore out. Shifting in my car is a lot better since the original clutch had like 145k miles and some change on it, but I still have the same problem.

If I am driving for an hour or so and in traffic no matter what I do 2nd gear begins to grind. But, before that everything else is normal and I have no issue driving in any other gear or reverse. The clutch is much smoother and I don't feel like the clutch is the issue, but I have driven a car with bad synchros before. It has usually been every time in the gear or causes it to pop out unless you double clutch it. But, I have never seen a problem like this before. I tried going a little thicker with the nissan fluid from the Motyl gear 75w80. Its just weird that it takes so long to act up, but when you talk to the trans place they say there is no problems.

 

[kschachn]

I’ve owned several manual transmission vehicles including my current ECHO and I’ve never seen a grinding problem that was caused by a worn clutch. That’s always resulted in slipping under high load. Also if you’ve tried several fluids and that hasn’t helped them it’s not the fluid.

At that low of miles I’d be surprised if the synchros were worn. You need to take the vehicle to a shop that knows what they are doing and get a proper diagnosis.

 

[DriveHard]

worn piston seals on the slave cylinder...as it warms, the fluid leaks more and more. Here is a couple tests you can run.

Get it nice and warm so that it "grinds" - push in the clutch for a long time, try to shift and see if it gets worse the longer you hold it. Or same thing, but keep it in gear on level ground and see if it starts to creep after a while.

 

[RooflessVW]

worn piston seals on the slave cylinder...as it warms, the fluid leaks more and more. Here is a couple tests you can run.

Get it nice and warm so that it "grinds" - push in the clutch for a long time, try to shift and see if it gets worse the longer you hold it. Or same thing, but keep it in gear on level ground and see if it starts to creep after a while.

Bingo.

Or "double" clutch. Press the clutch, take it out of gear, release the clutch. Press the clutch, put it in gear, release the clutch.

 

[Jcornwell101]

worn piston seals on the slave cylinder...as it warms, the fluid leaks more and more. Here is a couple tests you can run.

Get it nice and warm so that it "grinds" - push in the clutch for a long time, try to shift and see if it gets worse the longer you hold it. Or same thing, but keep it in gear on level ground and see if it starts to creep after a while.

The clutch kit they installed includes the slave cylinder as its part of an assembly directly attached to the throwout bearing. So the clutch slave cylinder was replaced and they bled the system with fresh fluid.

 

[Nessism1]

Could it simply be worn syncro's after 165k?

 

[Jcornwell101]

That’s all I can think of

They did show my my original clutch after 146k I was about to start having the rivet against my flywheel

 

[DriveHard]

The clutch kit they installed includes the slave cylinder as its part of an assembly directly attached to the throwout bearing. So the clutch slave cylinder was replaced and they bled the system with fresh fluid.

Maybe it is the master then?

 

[tiger862]

If you can shift without the clutch and problem isn't there then look at the input shift (highly unlikely) bearing. If problem is still there then synctros bad for 2nd. You can run high enough rpm that you can always skip 2nd or find someone that can replace that one synchro.

 

[Jcornwell101]

Turns out that second gear synchro left the chat, it needs a slider, shift fork, and half of the casing because of the shift fork.
With the miles on the transmission they are doing all of the synchros though.

 

[Chris142]

Bingo.

Or "double" clutch. Press the clutch, take it out of gear, release the clutch. Press the clutch, put it in gear, release the clutch.

Or learn how to float gears I only use the clutch to stop or start

 

[Jcornwell101]

Right now the transmission is taken apart and on the bench at the shop. They are waiting on the case half to come in and they will repair it. I have driven mostly all manual cars and this is the first time I ever had a transmission fail even with a lot of them being bought with high mileage.

 

[GMFan]

The 2nd gear synchro on my Mazda started grinding around 120K. I drove the car to 202K miles double-clutching 2nd gear. I got so used to it I never gave it a second thought. I’d be hard pressed to rebuild a transmission on a 146K economy car.

 

[Jcornwell101]

I have owned the car since new and owe a bit in it still because I bought it during a pinch in my divorce. I drive a lot for work and don’t have much of a choice until I pay it off.

 

[KrisZ]

It is likely a worn synchronizer so no oil will help it.
Learn how to double clutch, don’t confuse it with rev matching, and use this method whenever you go into the second gear.

 

[Jcornwell101]

I was in a bad situation and bought the car new in a pinch upside down. I drive a lot for work and still owe a lot. So I made my bed because of divorce fun now I have to fix it.

 

[Kurtatron]

It disheartens me hearing of a manual transmission failing. They’re supposed to be reliable alternatives to autos. I’ve never had one fail in my 15 years of driving them. is the repair cost reasonable? I would be very disappointed to be let down by a manual if I were in your position.

 

[Jcornwell101]

I have driven stick shift cars for many years as I prefer it. This is the only one I have has fail on me.
I think a contributing factor is the way the throttle by wire is tuned on this car. There is a big delay when you give it gas. Another thing is first and second gear are very short. Second you can’t really coast in heavy traffic in it. So it’s tricky to drive because of those things.