Valvetronic faults and failures…
Valvetronic is BMW’s latest answer to variable valve timing.
Valvetronic engines use an extra set of rocker (intermediate) arms, positioned between the valve stem and the camshaft. These intermediate arms are able to pivot on a central point, by means of an extra, electronically actuated camshaft (eccentric shaft). This movement alone, without any movement of the intake camshaft, can vary the intake valves lift from fully open to almost closed.
The system works very well in principle. The issues arise later in the vehicles life when components wear due to incorrect or overdue servicing. Below is a diagram illustrating the BMW N42 Eccentric shaft system as it is far the easiest to understand. This same system applies to the later BMW V8’s.
The eccentric shaft and rockers wear over time causing the vehicle to develop either poor running or a misfire. These rockers are so precisely made, they are individually numbered, this number is then ordered directly from BMW with a new shaft.
Poor servicing or after market oil filters are often the route cause of valvetronic failure. As you can see from the picture above, the after market oil filter on the right hand side has started to collapse. This causes the oil pressure to drop and accelerates the wear greatly to the valvetronic system as it is not getting the required oil to keep everything well lubricated. This is why we explicitly use genuine BMW oil filters.
When ever we repair a Valvetronic engine, we replace the needle bearings (pictured), eccentric camshaft, a complete set of rockers, oil filter and oil change with the correctly specified engine oil (often over looked elsewhere). On severely affected engines, timing chains and intake camshafts may require replacement.
Special tools are used to repair these Valvetronic engines. At Grosvenor we invest very heavily in tooling, ensuring you get a perfect repair every time.