I have an early '08 335d that seems to have developed a problem with the steering. Most particularly at speeds of 20-40mph, I can feel a pulsing sensation through the steering wheel during change of direction. It is as though the PAS is operating in little kicks rather than a smooth action. I thought that maybe it was normal operation for the car and that maybe I am over-sensitive due to the end of the warranty being imminent, but I could even see the wheel jerking as I watched it whilst turning. Does anyone have any idea what this is likely to be? I wondered if the dealer might try to wiggle out of it by saying that it is wheel/suspension damage caused by Sheffield's shitty roads, but the car is steady as a rock at motorway speeds.
I am not very knowledgable on BMW, but assuming your model has one (as opposed to conventional hydraulic power steering ) then it sounds like the electric steering column is faulty .
I had read about the problems that Z4's have had with their electric columns and it sounded similar. If they are hydraulic then the first step must be to look very carefully at tyres and wheels, because if they are damaged then they will be chargeable, after that if it is still under guarantee and there is a reproducible problem then just leave it to the dealer.
And to me, but I would also expect, if that were the case, for it to be affected by the weather. Ambient and/or engine temperature, rain, etc. Also any belt slip would be significantly higher during low speed manouvers like parking. If none of those apply, it would indicate the fault is something more complicated.. Mike.
I had a look under the bonnet of a 335d today, I do not think that it would be the belt slipping, it is a large 5-ribbed belt that also turns the alternator. If that slipped, you would know it.
If I understand the symptoms correctly, you are holding the steering wheel still whilst going round a bend and it is 'jerking'. There would not be a lot of power assistance to maintain steering angle.
I think that it is a wheel / tyre issue.
The first thing I would check is the tyre pressures, the tyre pressure monitor is not infallible and I wouldn't rely on it. I once saw one (335d) with 42 psi in one rear tyre, and only 5 psi in the other rear tyre and there was no difference in the side-wall deflection.
Are you running with run-flats (or more correctly in this case with BMW, self-supporting tyres), as these have strange wear characteristics as they get worn ?
Is one of the wheels buckled, if you have 18" or larger wheels, some are prone to have a weakness (not always), leading to buckling of the wheel ?
Is one of the sidewalls damaged, or does the steering wheel 'jerk' when turning both ways ?
There is something else I am aware of, but it is not the same fault you are describing; A lot of the E90 3 series I have driven from cold, have suffered from a 'clonk' from the steering system when going across a small (1" ) trough in the road very soon after starting and before any steering movement is applied. BMW know about this and said that it was a steering column issue, but it is still there in later models after they said it was resolved. The BMW ID for this fault is 5048038-05.
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