Re: E30 rear wheel bearing (s)

[alex.fadeev@xxxxxxxxxxx]

"Steve Ballard" <usaballard@domain.elided> wrote:
> 
> My 1991 318is (160K) has gradually acquired a loud whine.  I am assuming 

> it's a wheel bearing but I am still unsure. 

Steve,
Does the whine come from the front of the back? Does it vary with speed? 
Gets worse/better during a turn?
If you answered yes to the last two questions, you are likely looking at a 
dying wheel bearing. 
On my E30 all four went between 135-165K miles, so yours is just about 
due. 

> I raised the front end and wiggled the tires by grabbing the top and 
> bottom and got no detectable play. 

You will hardly ever get any play in the wheel. A BMW bearing will roar 
for 5-10K miles before getting sloppy. But that time you will either loose 
all hearing or replace it. The wheel play check is for complete basket 
cases.

>  With the wheels off, the disks spun easily though.  Then I raised the 
> rear of the car and use a trick I once learned from a BMW mechanic. 
> With the car on jackstands, I started the car and put it into gear so 
> that the drivetrain was turning the wheels (need to be careful with this
> one!).  Then I crawled under the car and used a long screwdriver as a 
> stethiscope against the back of the plate which holds the rear bearing.
> Both sides sounded like a bucket full of rocks; so I assume that both 
> rear wheel bearings will need replacing. 

Wheel bearings rarely fail in pairs or number greater than one. Also, 
having two rear wheels in gear introduces all sorts of interesting noises, 
not least of which are pads dragging on the rotor and the rear diff whine 
present on all 100+K E30s.
9 out of 10 cases the front wheel bearings are the first to go. Make the 
front outside wheel if you track your car. 

> I am still a little unsure, though.  Could bad CV joints give me 
> the same signal?  Any way to better diagnose this?  I can't tell 
> any difference in the whining on left or right turns, but I guess
> I wouldn't if both bearings were bad.

Again, more likely than not only one of them is bad. Listening for the 
roar to subside or increase during turns is a the dead give away of a bad 
wheel bearing. It is more difficult to pin point the side of a dying rear 
wheel bearing unless you have someone to sit in the back seat/trunk during 
turns. If your noise is coming from the back but does not wary during 
turns, it's probably something else. Like a noisy diff.
FWIW, in the 220+K miles and numerous DEs I had put on my E30 before 
selling it last year, I never had a problem with the drive half shafts 
(aka CV joints).

alex f

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