How to bleed air from a BMW clutch actuator

It's not exactly rare for BMW drivers to run into a situation where the clutch suddenly starts behaving oddly: either it disengages poorly, or the pedal returns with a noticeable delay, or it simply starts, as they say, "sticking". In this case you can say with next to zero risk of being wrong that the problem is air getting into the hydraulic system. So there's no need to get upset, and certainly no need to go shopping for BMW parts – you just need to bleed that very air out of it. Of course, you could go to an authorised service station for this, but if you'd rather not spend the extra money, it's better to try fixing this fault yourself.

Before we get to describing the process, though, a few words are in order about some safety rules. The thing is, the hydraulic system of a BMW clutch is filled with nothing other than brake fluid, which, as you know, is toxic, and so under no circumstances should it be sucked out through a hose. On top of that, any fluid drained in the course of the repair needs to be stored in a sealed container.

Before you start bleeding air out of the clutch actuator, you first need to check the brake fluid level. Top it up to the maximum mark if needed. There's a special bleed nipple on the slave cylinder for removing air – remove the protective cap from it and fit a clear plastic hose in its place. Next, use a ring spanner to carefully check that the nipple turns freely, and put the other end of the hose fitted to it into a container of brake fluid. After that you'll need to ask someone to press the clutch pedal several times and hold it down. Now carefully loosen the nipple with the ring spanner and wait until the fluid flowing out through the hose stops containing air bubbles. As soon as that happens, the nipple can be closed. Then the whole process should be repeated several times until the air bubbles disappear completely. Throughout this, keep an eye on the brake fluid level so it doesn't drop too much, and top it up as needed. Once the air has been bled out, turn the nipple back to its original position and put the protective cap back on.

So, bleeding air out of the clutch hydraulic system is not difficult at all, and it doesn't require taking apart any part of the BMW. All you need to do is strictly follow the safety precautions when working with brake fluid, and follow the procedure described above exactly.