What is a Valvetronic Engine?
Valvetronic is BMW’s latest answer to variable valve timing, replacing their previous VANOS system. 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 on in the vehicles life when components wear or 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 shaft and rockers wear over time causing the vehicle to develop a misfire. These rockers are so precisely made, they are individually numbered, this number is then ordered directly from BMW with a new shaft. Whenever 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 overlooked elsewhere). Special tools are used to repair these Valvetronic engines. At O.G.S. Mechanics we invest very heavily in tooling, ensuring you get a perfect repair every time.The shaft and rockers wear over time causing the vehicle to develop a misfire. These rockers are so precisely made, they are individually numbered, this number is then ordered directly from BMW with a new shaft.