Right, VVT BMW, HUGE expense. LOW oil pressure cause all this time for a rebuild...188275 miles Faulty exhaust side hydraulic valve lifters (HVA) can cause a ticking noise after the engine is warmed up in some 2006-2008 models with the N52 engine. Some owners report the noise temporarily disappeared after a long highway drive or switching to different type of engine oil. As per one of the BMW service bulletins (SIB), the 12 exhaust side lifters must be replaced with updated parts ($1,200-$2,000 repair). In some cases the cylinder head also had to be replaced to completely resolve the problem. "The Valvetronic motor is used on BMW E90 models with a normally-aspirated engine. It is responsible for actuating an eccentric shaft that adjusts intake valve lift. The motor itself is pretty reliable and does not fail too often. However, you will have to remove it for other engine repairs and the gasket that seals the mounting surface of the Valvetronic motor fails and leaks oil. When repairs are performed on the Valvetronic assembly, the limit stops have to be relearned. You will need access to a BMW scan tool to do this procedure. The limit stops are the mechanical limit stop, end to end of rotation of the eccentric shaft. The DME (digital motor electronics) records these stops via the eccentric shaft sensor to determine mechanical adjustment limits of the eccentric shaft. With that said, when removing the motor to replace the gasket you are not changing the mechanical position of any Valvetrnoic assembly components, a relearn is not always needed. Now use this with caution and when in doubt, perform the relearn. Do your research and check with up to date repair information before beginning."
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