grinding noise

[pyro]

Hi i just noticed when i accelerate from a stop i feel this grinding noise. it comes from behind the drivers seat (i think) so im wondering coudl that be the dif? or is just a normal problem w/ a m50 transmition?

[shogun]

Check
engine mounts
trans mounts
center bearing

[Blitzkrieg Bob]

at a pitch that would get higher as you accelerate, and quiet down when you coast.

[pyro]

i know what a centerberring feels like when it goes out and its not that because when i apply power in seccond theres no vibration... its only from like 0-15mph
how do i check tranny mounts and engine mounts? if i repplace should i get uuc ones? but i have a auto tranny so i don't think they will help

[pyro]

my firends car had the center berring and trans mounts go out and i kno how that feels. it goes completely away at 10 to 15 mph its like that initial accalaration. i think its heat related because in the morning when i go to school. i leave my street and am yet to feel it or hear it then but after that during the day it happens. that leads me to bieleve possibly no fluid in the diff but i don't know

[shogun]

They are oil filled. So you can see oil 'moisture outside.
http://www.nmia.com/~dgnrg/mmount.jpg
If they are defective, the engine and the trans are 'hanging' in a different angle. This can cause also the drive sgaft to be out of the right angle and then you could get such noise.
How to change, see Gale's page. Link on my website.

Defective engine mounts also cause vibration in idle.

[pyro]

alright ill put my car up on the lift at school and give it a look. is there a way to check the motor mounts?

BTW thanks for all of your help with my car

[shogun]

Check for oil outside, and cracks. Sometimes they are worne so that metal touches metal.
I changed both engine and trans mounts last year. Engine idle much smoother and trans shifting is smoother (at least I have that feeling).
http://www.nmia.com/~dgnrg/page_10.htm

[Jason]

maybe one of your brake calipers is frozen... does it happen when you hit the brakes too?

[pyro]

no i just changed the fronts and took the rear pads off and inspected them... so not the brakes

[NickM535]

I know exactly what you are talking about because i have the same problem. Unfortunately i havent been able to pinpoint the problem- I hear this noise mainly when i am going slow such as up my driveway or in a carparking lot. I'm taking my car to BMW on thursday i'll get them to have a look and see what they find- then i'll let you know what they find. In the mean time good luck

[Andryuha]

Hi i just noticed when i accelerate from a stop i feel this grinding noise. it comes from behind the drivers seat (i think) so im wondering coudl that be the dif? or is just a normal problem w/ a m50 transmition?


I had the same problem - turned out to be a rear wheel bearing. You could easily check it by jacking up the rear of your car. Then remove the rear wheels and start the car + put it in gear. Then step out and listen to the noises. If it's the grinding noise that seems to be emitted by one of the axels, then it's almost certainly a bad bearing

[pyro]

will do tomrow thanks for the hint

[NickM535]

Hi Pyro,

Took my car to BMW today and they had a look at that noise- they say its a centre bearing, will cost around $180.00 for the parts. thats Aussie dollar

[pyro]

explain what your grinding noise was. was it only when starting from a stop? I think it may be the same thing with me (thats what my firend said) also i think the trans mounts could be shot to. Ill give it alook

[DanH]

...the driveshaft would grind against the heat shield above the resonator/exhaust. It would grind loudest when decelerating.
And quiet down mostly on accelleration. All center bearing failures don't sound the same, it depends on how bad it is. Its a $30 part and a few hours of labor, not real hard, just time consuming.

That would be the most common failure anyway, could be the other things people have mentioned also.


explain what your grinding noise was. was it only when starting from a stop? I think it may be the same thing with me (thats what my firend said) also i think the trans mounts could be shot to. Ill give it alook

[NickM535]

explain what your grinding noise was. was it only when starting from a stop? I think it may be the same thing with me (thats what my firend said) also i think the trans mounts could be shot to. Ill give it alook
Ok my grinding noise was most noticed when driving slowly, like around a car parking lot or something like that- not only from a start to stop, but up and down
I could only hear it when going really slowly.

[NickM535]

How did you go with your car Pyro??

[pyro]

i inspected the bushings used a pry bar to try and wiggle the trans... all solid drive shaft seems to be VERY soid. im mind boggled to what it may be...