BMW 3.0-litre petrol speed hump damage

Posted on May 11th, 2017 by Rob Marshall


We tend to find that potholes, speed humps, et al, cause the most damage to suspension and bodywork components but Autoelectro has alerted the motor trade to an altogether different problem that afflicts 3.0-litre 3-series BMW petrol models.

According to the company, which re-manufactures starter motors and alternators, driving over speed humps can cause either the power assisted steering pump pulley, or the auxiliary drive belt, to strike the subframe, which attaches the engine and suspension to the bodywork. This cases the belt to either stretch, or break, and this causes a premature failure of either the alternator, or power assisted steering pump pulleys, or both.

Therefore, should you own a 3.0-litre BMW (E90, E91, E92, E93 335i, made from 2008), check the integrity of both the pulleys, as well as the condition of the left hand engine mount, prior to replacing a damaged auxiliary belt. As the pulleys are replaceable, it might not be necessary to change the complete alternator, or pump, but ask the advice of your mechanic before sanctioning the needless replacement of parts.