Issue after changing t case and rear diff fluid

[darrylwmiller]

I changed my T case and rear diff fluid and filled both up until it was dripping oit of the fill holes. I took it for a test drive yesterday on the highway yesterday and it seemed fine.

I drove to work today (45km) while running CVTz50 app to look at transmission temps. Everything seemed fine until I was pulling in to a parking spot and gently applied brakes (had to push harder then normal) and I was not quite straight, so I went to reverse and and the brakes were not working at all while engine started reving as I tried to depress the brakes. I switched back into drive as there were people behind me and I felt the car jutter like it had engaged. I drove forward and brakes seem to work again, did a small lap around the parking lot and it seemed fine.

Could this be related to the fluid change? I Used Lucas 80w90 gear oil on both.

Could this be related to running the app while driving? Doubtful but you never know I guess.

Still baffled by the relation to brakes not working along with this issue. The brakes did not feel spungy, they felt a bit more stiff.

Appologies for all the questions lately, seems like things are always malfunctioning lately.

[VStar650CL]

The brakes are vacuum-boosted, so it sounds more like an issue with the engine than the drivetrain. Check the big boot connecting the airbox to the Throttle Body. When those get torn they'll often open up randomly and create a huge leak whenever the engine rocks in the mounts, such as shifting D->R or acceleration/deceleration. The ECM doesn't know how to respond to the rush of unmetered air, so all sorts of weird behavior can occur.

[darrylwmiller]

The brakes are vacuum-boosted, so it sounds more like an issue with the engine than the drivetrain. Check the big boot connecting the airbox to the Throttle Body. When those get torn they'll often open up randomly and create a huge leak whenever the engine rocks in the mounts, such as shifting D->R or acceleration/deceleration. The ECM doesn't know how to respond to the rush of unmetered air, so all sorts of weird behavior can occur.

I will check that out tonight. Kind of caught me off guard as a I had never experienced that before.

[darrylwmiller]

I checked the boot going to the throttle body and it seems in good condition, felt around the back side of it and could not see any rips. Seems pretty flexible still. I am going to check airbox tomorrow before going to work and double check for leaks below. I drove home today with no issues, and when I pulled into the driveway I threw it in reverse and back to drive with no issues - Not sure what that was all about earlier.

I did have a noise for the last couple of weeks which I summed up to my last wheel bearing going. I had the rear right replaced about a year and a half ago and the front left and right mid last year so I had assumed the fast thudding noise was just the last bearing going. I uploaded a video of the sound - ignore the wind whoosing, it was windy tonight on the highway.

[https://youtu.be/WLx9bOLk2Jo?si=BYt09AqCkP0GmN3X]

[VStar650CL]

I'd say that's a likely diagnosis. The archetypical death noise from a Nissan-type roller bearing is a "roar" that gets louder with road speed, and I'd say your noise qualifies.

[darrylwmiller]

Well, as of right now I am at a loss and wondering if it will happen again. Drove another 100kms to work and back today and all seems fine. I will have to dig in more and see if there are any leaks from brake hoses to the booster on my day off.

The strangest part was it felt like the car had a complete loss of power and the brakes were barely functioning with stiffness as I was pulling into the parking spot before I even put it in reverse. Once in reverse seemed like I had no brakes with loud engine rev, loud enough the people were looking like wtf. Once back in drive the clunk sounded like gears engaging and all was back to normal.

Do you think there is any possibility that running the cvt app from my phone could have any impact on anything? Seems like it should just be reading data and not doing anything bi directional.

[VStar650CL]

I very much doubt that CVTz50 would mess anything up, but I suppose the dongle could if it was malfunctioning. Have you checked to see if your battery voltage is doing anything wonky? On cars with "smart charging", it's not unheard of for the CANbus to freak out if the smart charge gets stupid and lets the battery go below 11.6V. I just had one in the shop the other day, an R53 Pathfinder that was having mysterious (and scary) episodes of going all over the road when on ProPilot, like it had foggy glasses. It also had mystery codes for the ECT sensor and the electronic thermostat, even though there was nothing wrong with those parts. With no voltmeter on the dash, the problem was completely invisible to the customer, she just decided her car was haunted. New battery, new alternator, problem gone.

[darrylwmiller]

Very interesting. It is original alternator, battery was new last year. While I am investigating things on Tuesday, I think I will monitor battery with my multimeter and also use the app withbthe same dongle. I appreciate all the aupport and feedback on the issue. It would make sense, as it was if when I shift into reverse the car sis not recognize it and just rolled until suddenly it grabbed in an instant cause a jerk.

[VStar650CL]

I think you can put Vbat up on CVTz50, or you could stick a voltmeter in the power socket. When they malfunction it's never continuous. Usually they bounce up and down from around 12.2V or so to normal charge voltage of 14V+. That's normal. When they're having an episode of stupidity, they'll keep going down and down below 12V and the alternator won't kick in. Then you cycle the ignition and suddenly it's 14V again. On cars with LIN alternators (which yours has), that always means the alternator controller is shot.

[darrylwmiller]

I ran vbat this morning on the way to work and it seemed fine up until a few minutes before I arrived. It dropped to 0 briefly but I did not notice or feel anything. I will say the brake pedal has felt more stiff the last few days since this started. Going to check again today on the way home and report any findings back.

It looks like there is always a slight voltage drop when coming to a stop but only once did it drop to 0 which correlates to another time I was stopping and possibly depressing the brake harder to check firmness.

[VStar650CL]

The 0V spikes have to be a sampling artifact (unless maybe you have a bad battery lug). You'll probably need to just keep an eye on it to see what it does if and when the car misbehaves. We drove that R53 for a bunch of miles and couldn't duplicate the behavior, then it ended up dropping out after idling 30 minutes in my bay while checking other things. We basically discovered the falling voltage by accident.

The brakes are strictly vacuum-boosted on a non-hybrid gen2, the only electronic actuation is from the ABS. Is it possible your ABS has an issue? Yes. If you don't have a scanner that can read it, hit AutoZone or O'Reilly and see if there are any codes in it. If not, you might have an issue with the booster or check valve.

[darrylwmiller]

Will do, I don't have those places here. I do havee my blue driver code reader and a thinkdiag code reader which I have to renew my nissan license on. I will keep an eye on battery for now.