Noise/Vibration Issue.

[rednelb]

I picked up an '07 M35x last month with 140k miles on it. Runs nice, excellent interior and paint is in great shape too.

A couple of days of driving it around (a lot), I noticed what could best be described as a wheel bearing issue. Groaning type of noise that didn't seem to change with engine or wheel speed. I could also feel it on the gas pedal. I could feel it more when I let off the gas. Turning right made it go away, turning left made it worse. It could best be described as driving over really light rumble strips.

Replaced front passenger wheel bearing and still had the same problem. I rotated tires to see if the issue would change or help me eliminate what the problem is. Nope. I did notice a steering wheel shake after the rotate that seemed to have the same "rumble strip" vibration.

SO... I put brand new tires, balanced, and aligned everything. (Original alignment was all within spec except for the rear drivers side toe) There is no steering wheel shake anymore and I don't have any pulling of the steering wheel, but the same vibration/noise exist. Still feel it on the gas pedal too. I do not feel it when braking.

One other thing I will mention... when driving, I will shut off the A/C but the vibration still exist... when I am parked and idling with the AC on, I can feel and hear the same type of groan, but it doesn't flutter like rumble strips, it is just a constant sound and vibration. If I turn off the AC, then it goes away.

Could it be the AC compressor?

Thanks for any help
-red

[Ilya]

I don't have any experience with AC compressors...but perhaps EB will chime in...he seems to be knowledgeable in all things...

When I first read about your groan I thought bearing too but you took care of that...turning the AC off/on would seem to suggest your guess.

[EdBwoy]

If the noise or vibration frequency changed with RPM, then I'd guess the AC compressor or even power steering pump. Ya know, the things that spin faster when the engine turns faster... including the torque converter which could more likely be felt in the car.

Then you said you'd feel it even with the car in park, and it changed with the AC turning off, and that sent me to the cooling fans. I believe the driver side one is the secondary one in most 2-fan Nissans. Does the vibration come on as soon as you start the car or when the car warms up?
Of course, this shouldn't be related to turning the steering wheel.

Quick question to clarify; when you say you turn the AC off, do you mean the entire system off, including the fan?
This question is leading to the blower fan bearings going bad, but again that's under the dashboard/ behind the glovebox and I don't see a direct correlation to your pedal.

[rednelb]

Thanks for helping me with this....

When I turn off the AC system, it is full off. I will also clarify, that when in park and I feel the same vibration.. what I mean is that it is around the same frequency or tone, but it is constant. When driving.. AC on or OFF, I get the vvvvv.....vvvvvv.....vvvvvv feel. When I start the car up in the morning, I don't seem to feel it until after the first time I need to get on the gas. From that point, it is pretty constant.

One thing I should have mentioned... when I was replacing the bearing, the drive shaft spline wasn't lined up with the hub spline very well at all. Almost to the point where the teeth were point to point. >< ><
I hope that makes sense. I had to purchase an axle puller and use a breaker bar turn by turn to push that damn thing through. Amazingly, the teeth looked fine and the new hub went on like butter.

So part of me is leaning towards something ran by the belt or something odd in the drive shaft.

[EdBwoy]

I was thinking driveshafts, axles, transfer case or front differential but again those shouldn't be turning when the car is in park. Only the torque converter in this case.

With the car shut off, go and spin the rad fans by hand to see if any one of them makes a grinding noise, just so we eliminate those.

[rednelb]

I haven't had a chance to check the fans, but after a long weekend of driving, I keep leaning towards the bearing. Even though it was just replaced.

When I turn right, especially on long hard turns (like on/off ramps) the car feels smooth as butter.

Could it be the rear bearing? I spun it while I had it jacked up the other day and it didn't feel rough or wobble at all.

[EdBwoy]

Could be a bearing, but it shouldn't be a factor while the car is parked.
Btw, what kind of bearing did you use - OEM?

How about your idle RPM - is it constant, and not jumping at this time?

[rednelb]

Idle is constant.
I think the vibration I get when parked is a separate issue. It just feels the same through the gas pedal.

I used the Timken bearing as recommended by this forum.

[Phrozen45]

@rednelb
What ended up being the final issue? I think I might currently be having a similar problem... Within a years time I replaced front bearings and now I'm currently hearing a loud noise as I drive after like 10mph (loudest at 20-65mph). If I slow down the noise loses volume and is not there while parked, idle (like at stop light) nor when in neutral so probably not engine related since no noise when not in motion. I appreciate any help...