M Klasse Spongy Brake Pedal and Low Fluid

A spongy brake pedal and low fluid is rarely a good sign. I had a similar thing happen with my M Klasse. First, check your brake lines for leaks. Brake fluid is corrosive. Then check the brake pads. If they're worn, the fluid level drops. What feedback are you getting from the pedal?

I checked the brake lines and didn't see any leaks, but I'll check again. If the pads are worn and causing the low fluid, would the pedal feel be affected that much? The pads aren't completely worn, but they're probably due for replacement soon. What do you mean by 'feedback'?

The brake pedal feel is affected by worn pads because you're pushing more fluid to get the same braking force, hence the spongy feel. It's best to get it checked by a workshop. It sounds like worn pads, but it could be a missed leak or a faulty master cylinder. If you refill the brake fluid, use the correct brake fluid, usually DOT4, it's on the master cylinder reservoir cap.

My mechanic confirmed it. Worn brake pads were the problem. I had them replaced, along with a brake fluid replacement. It cost 480€. The brake pedal feels normal again. Thanks!