My MIL brought a friend's vehicle over for me to take a look at. 2013 Altima SV w/ 2.5L & CVT, 105K miles. Did a thorough test drive and here are the symptoms:
Drivetrain noise is present anytime the car is moving. It can fade into background noise easily at very low speeds, but once you're running 40+ MPG, it sounds like there's a second engine under the car turning about 2X the speed of the engine, with an accompanying light coarse vibration located in the center/front of the car. Get up to 65-70+ and it sounds like I'm redlining this phantom engine.
Things I know:
CV axles, wheel bearing, suspension, rest of drivetrain checks out. Turning makes zero difference in sound.
I've driven a few of these so know what to expect of the CVT. Ratio selection/behavior seems appropriate for the model-- RPM responds well to throttle position, engine accelerates normally. I can easily separate the engine noise from this other sound and it's definitely not the engine; it sounds like a 2.5L should. WOT acceleration is fine and has the fake shifts around 6K like you'd expect. No CEL.
My thought is that the only thing that can cause this type of noise/vibation and be perfectly linear with speed is the differential in the transaxle. Is this a common failure point, or do you think I'm barking up the wrong tree? I simply don't see anything else wrong with the car.
Transmission has a minor leak, didn't have time to narrow it down. I'm told (by MIL, a third party) that she had someone service the transmission a while back. I was in a hurry as we've been under tornado warning most of the afternoon/evening, but I suggested she bring it back and try a drain fill so we can ensure the fluid level and type is correct. That will help narrow down whether she can get by for now, or whether she's looking at a very expensive repair soon.
Curious what you all think. Any thoughts / suggestions / input are appreciated.
Drivetrain noise is present anytime the car is moving. It can fade into background noise easily at very low speeds, but once you're running 40+ MPG, it sounds like there's a second engine under the car turning about 2X the speed of the engine, with an accompanying light coarse vibration located in the center/front of the car. Get up to 65-70+ and it sounds like I'm redlining this phantom engine.
Things I know:
CV axles, wheel bearing, suspension, rest of drivetrain checks out. Turning makes zero difference in sound.
I've driven a few of these so know what to expect of the CVT. Ratio selection/behavior seems appropriate for the model-- RPM responds well to throttle position, engine accelerates normally. I can easily separate the engine noise from this other sound and it's definitely not the engine; it sounds like a 2.5L should. WOT acceleration is fine and has the fake shifts around 6K like you'd expect. No CEL.
My thought is that the only thing that can cause this type of noise/vibation and be perfectly linear with speed is the differential in the transaxle. Is this a common failure point, or do you think I'm barking up the wrong tree? I simply don't see anything else wrong with the car.
Transmission has a minor leak, didn't have time to narrow it down. I'm told (by MIL, a third party) that she had someone service the transmission a while back. I was in a hurry as we've been under tornado warning most of the afternoon/evening, but I suggested she bring it back and try a drain fill so we can ensure the fluid level and type is correct. That will help narrow down whether she can get by for now, or whether she's looking at a very expensive repair soon.
Curious what you all think. Any thoughts / suggestions / input are appreciated.
