Bad noise from the tranny!

[18bob14]

Hi Guys,

Looking over the net and found your forum.

I have a problem with my UK spec 92' 525i auto. When on the highway, slowing from 70/80mph, I can hear grinding/flapping noise from the tranny. At any other speeds below this, the noise doesn't happen and all the changes are smooth (except going up into 3rd - see later). I've driven the car about 20K miles in two years (now has 145K on the clock) without a hitch.

Could this be something as simple as the engine/tranny mounts wearing out or am I looking at big expense?

For the sake of clarity, my tranny is one of the 'sealed' units without a dipstick.

Sorry for the long thread but any of you out there have any ideas on why the tranny hangs before going into 3rd? All other gears are fine.

Thanks in advance for any help offered

[Bill R.]

Guibo, which is a rubber /cloth coupling between the driveshaft and the transmission... when they start to disintegrate they can make a flapping sound, or if you have a bad center bearing mount on the driveshaft and suddenly reverse the load it can make a scraping flapping noise.. Thats the first place i would look.. The 3rd gear gear change is unrelated... Are you sure thats not just the normal lag when the engine is cold? There is a lag built in when the engine is cold to delay the shift so that the engine runs longer at higher rpms so it will warm up quicker.

[18bob14]

Hi Bill, thanks for coming back to me.

I'd picked up that it might be the guibo but the centre bearing was a new one on me, I'll check the car over this weekend and see if everything's OK.

On the 3rd gear, the car has always hung a little since I bought it but now it takes ages to engage when warm. When cold, it changes up when approx 3000 revs is reached but shouldn't it be a lot smoother going when it's warm?

Cheers

[philbyil]

While you are at it, you should replace the CB if the Guibo is gone and vice versa....