hello
My car is making humming noise from rear when pressing gas. The sound gets louder as speed goes up. As soon as i release the gas pedal and car is just cruising the humming sound stops immediately. This sound reminds me worn bearing or smt similar. I was suspecting wheel bearing but in that case it should hum all the time not only when gas is pressed. So next logical place would be differential. Is there any bearings in differential or any other bearing thats connected with power output?
Pull the car's code; this will give you a definitive place to start looking/troubleshooting. Best of luck!
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I would suspect the pinion bearing in the differential, or more probable is a bad u joint.
Driveshaft related.
Check rear differential fluid level, inspect for leaks.
Is there a central, or mid-way, drive shaft differential on the series 3? Drive shaft issues, 'Germans' use something other than 'American universal joints' that more resemble cv joints...but are not. My A6 had dried out grease spun out to the sides from over the 14 years...after repacking, all was well...60k ago.
Flex joint aka a Guibo,
Center mount aka Center Support Bearing.
The driveshaft is being loaded in one direction when the throttle is applied and then unloaded when coasting.
When a U-joint in one of these cars is bad, it will cause the shaft to vibrate when coasting and go away when the throttle is reapplied. Could be flex disc as well, but its definitely in the driveshaft.
No leaks, differential is clean
Both swapped out last week, no changes
Also had my wheels balanced + alligned
Saw the price of pinion bearing and its like 3x more expensive than new used diff, today i am trying to go underneath the car and maybe record the drive shaft & differential for more information and then make up my mind if i should buy a new differential or maybe a rear part of drive shaft because the vibration/sound/whine/clunks are really coming from the area where diff meets drive shaft.
Daaarn i cannot wait to solve the problem, its really the last thing on my bimmer needs to be fixed, finally :x:x:x
Last edited by gurmaan9; 07-19-2017 at 02:21 AM.
Maybe the rear wheel bearings or the rear differential/component in the differential.
Everyone whose bet was drive shaft are correct.
Rear U-joint is very loose, gonna buy new one and update this thread soon
Yep, the car is super, SUPER quiet now
Cannot tell if im driving 50mph or 110mph, so quiet and smooth
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