Can I change timing chain tensioner

You can replace the timing chain tensioner on a BMW engine if the engine is running normally and there are no signs of timing chain issues. Before installation, immerse the new tensioner in clean engine oil for at least 10 minutes. This allows the internal chamber to fill with oil and purge any trapped air. You may notice small air bubbles escaping during this process, which is normal. Install the tensioner by hand first. Tighten it until you feel resistance. If it is not fully seated by hand at that point, this generally indicates that the timing chain has not stretched excessively and the tensioner is applying pressure to the chain guide as intended. Once hand-tight, use a torque wrench to tighten the tensioner to the manufacturer's specified torque of 70 Nm. After installation, start the engine and check for any abnormal timing chain noise. One note: on some BMW engines the timing chain tensioner torque specification differs from 70 Nm, so it's worth confirming the exact engine code (N47, B37, N13, etc.) before applying that value.