Loose Pinion Bearing Preload

[100%Saab]

When I lift my foot off the gas pedal at times I will hear a soft whirring noise. I have a 2008 9-3 2.0T SS with 75,000 miles on it. Does this sound like a loose pinion bearing preload or something else? Is it something I should be concerned about? Noise is intermittent and seems less is I lift my foot off the gas pedal slowly.

[100%Saab]

So the transmission fluid gets changed at 76,000 miles three weeks ago and no change. Today the temperature was in the mid eighties. Sound is completely gone. There has been no problems starting my 9-3 or driving it. So, is this good news or not? Saab Service Center did not noticed any problems with the car when it was in 3 weeks ago when the temperature was in the 40's.

[100%Saab]

Temperatures today hit 90 degrees F, but morning lows have been in the 40s this past week. The whirling noise occurs only when I lift my foot off off the gas pedal. It stops completely if I hit the brake. The noise is present at 40 degrees and gone at 90 degrees. The sound lessens the higher the temperature. It is best heard if I accelerate first then lift my foot off the gas pedal. This I notice particularly on streets with stop lights and speed limits between 40-50 mph(stop then go). If I ease my foot off the gas pedal I don't hear the noise. No problems with driving the 9-3. Any thoughts?

[Digger]

Most likely cause is confused program, next most likely cause is bad temp sensor, then the next most and the next most and the next most. All I can say here with any kind of certainty is that this is probably not your pinion bearing preload and you will need to have a Tech 2 with security access to find and fix.

I don't know enough about Saab software to say for certain, but Saturn used the same kind of tranny and they could get the same kind of flaky. If the battery went dead and got jumped to start, or you had the cables off to remove or replace the battery, or somebody welded a new pipe on the exhaust or a trailer hitch to the car, the tranny controller could have gone into learn mode and it didn't get taught how to let go when it's cold. Or the Engine controller got confused and is confusing the tranny controller, or you have a flaky temp sensor, or all of the above, or something else completely different happening inside the tranny.

Volvo also used the same tranny and when they programmed up the controller for the first couple of years of manufacture, they wrote in a very reasonable fuel saving instruction that fried several thousand tranny's before they were able to undo what they'd done and how long they lasted before they fried depended entirely upon how they were driven.

What I can say with some certainty is that the tranny by itself is pretty darn solid and the adaptive technology programming appears to be the cause of most problems. So that you can have some idea of what you've got going on inside your tranny, my best suggestion is divorce the ECM and the TCM, add them back to the car and when the tranny fluid is at the right temp train it up the right way and see what happens the next time it's cold.

[100%Saab]

Paid attention to what you wrote, Digger. So, I made a recording of the noise after it became more promenent this fall with lower morning temperatures. Easy to hear in the morning and hard to hear in the afternoon when it is warmer. The noise is too hard to hear with the tire noise in the background. Saab Service Center in Florida couldn't hear the noise on the recording for my Texas 9-3. There also is a longer less noticeable noise on acceleration. Florida Saab Service Center suggested a loose heat shield. When my 9-3 had a local oil change, I asked to have the heat shields checked. The heat shields were reported OK. What was loose was the tailpipe exhaust hanger mount. Mounts are ordered, which is another story. We will see if it fixes the problem. Any comments?

[Digger]

Having spent maybe a hundred hours or more ten feet in the air on a ramp hoist with one foot on the brake and the other on the gas and the car in gear while someone walked underneath banging on the exhaust finding everything from a split gasket to loose baffle inside the muffler. I wouldn't be a bit surprised if a new exhaust hanger fixes your noise.

[100%Saab]

So, tailpipe exhaust hanger mount was stretched. Replaced single mount made a big difference, so replaced all 6. Noise on acceleration which had become more prominent is now completely gone. Other noise seems better but may not be completely gone.

[100%Saab]

So the acceleration noise is or almost is completely gone, however the deceleration noise is still present. The noise has a pitch to it lasting only 1/3 of a second. It sounds like a vibration or rapid flutter which changes quickly from a higher to lower pitch until it stops. The noise is not loud enough to be heard on a cellphone recording due to the background tire noise. Colder temperatures in the 40's f make the noise more prominent. Abruptly lifting my foot off the gas pedal after accelerating primarily causes the noise. Clearly this is a short sound produced by abrupt deceleration. Braking does not cause the noise. Slowing after a steady speed does not produce the noise and slowly lifting my foot off the gas pedal does not cause a noise. No other problems with my 9-3 with 81,000 miles on it. No codes showing either. The noise is now occurring multiple times daily. Any new thoughts?

[Digger]

Along with the transmission the drive train includes axle shafts with CV joints and wheel hubs with bearings inside. I can't hear what you're hearing, but hubs and CV joints make their own subtle and very recognizable noises when they start going bad. I can only suspect that the people who service your Saab know these sounds and have done what I would to check for these noises.

Long story short, tire noise can sound like a bad wheel bearing and tire noise can hide the sound wheel bearings make when they start going bad. CV joints usually click before they start to slip and clunk, if the boot doesn't split before the joint gets so bad it won't hold the car when parked on a hill, even the transmission pros can misdiagnose a bad CV as a bad tranny park pawl.

When checking for these tell tail sounds I like to use warehouse walls, they are usually in areas that get quiet after business hours, have large straight concrete walls that send every little sound right back to your ears and their empty parking lots provide plenty of room to maneuver and do your abrupt deceleration. Roll the windows down and listen for everything you can hear while making slow tight, wheel lock right and left turns.