Quiet Noisy Hydraulic Lifters, Tappets in BMW and MINI Engines
DON’T IGNORE NOISY HYDRAULIC VALVE LIFTERS IN YOUR BMW OR MINI!
Most later model BMW and MINI engines employ hydraulic valve lifters (or tappets). The hydraulic lifters use oil pressure to adjust a plunger and take up all the clearance in the valve train (vs. a mechanical lifter which must have a specific clearance periodically adjusted). This helps to ensure less engine noise, less maintenance cost and longer reliability, due to less wear and tear.
Hydraulic lifter can wear and not properly hold oil pressure, resulting in a tapping noise from the valve train clearance now created. Similarly, the small oil holes and passages within the lifter can clog due to oil varnishing or sludge build-up (all too common with today’s hyper-extended oil change intervals). The valve train clearance created by a worn or clogged hydraulic lifter, is what causes the typical tapping noise. Not only is the noise annoying, but more importantly, it can result in increased wear to the camshaft lobes, rocker arms, valve stem tips and the lifters themselves.
Replacing hydraulic lifters is usually a rather involved task and can cost hundreds of dollars. The most common fault in a noisy lifter is clogged or restricted oil passages. Liqui Moly Hydraulic Lifter Additive is specifically formulated to clean the lifter oil ports and passages, returning the lifter(s) to full operation and quieting the tapping noise and preventing the potential valve train damage.
Simply add one can to a fresh oil change and run the engine through the normal oil usage cycle (5000 to 7000 miles, using a high quality full synthetic oil, such as Liqui Moly). The noisy lifters should quiet down as the miles go by. Stubborn lifters may require a second application.