Okay. I have a Euro 1985 280sl. Going into work this morning, the brakes went almost to the floor. I was able to get it stopped in my parking lot. Started pumping the pedal to get some pressure, and the engine idle lowered. I am able to repeat that by pumping the pedal. I get some pressure when I do that, but the engine idle continues to lower. When I quit, the idle returns to normal. The fluid is fine, and I still have some brakes, but not enough to really be safe. My guess is a vac. leak. Is that right? If so, where do I start to look? Master cylinder? Like I said the fluid is full, but I have noticed the car pulling to the left when I brake.

Thanks.

Glenn Swartzfager

This is a classic case of a bad master cylinder.
Replace, power bleed and replace all fluid.

You should be set to stop.

Dave

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Dave

it sounds like the brake booster has developed a leak. this will let air leak into the engine when you puh on the brake pedal, and the pedal will go to/almost to the floow before catching and it will take lots of foot pressure to stop.

booster is non-repairable and not cheap.

If the pedal can go to the floor then it's not a booster problem.

Does the brake pedal go to the floor when the engine is off?

Most likely the master cylinder, check for any external leaks at rubber hoses and calipers as well.

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Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32

The brakes go to the floor when the engine is not on, so it sounds like it must be a master cylinder problem. I bet the engine idle was being affected by the amount of vac. being used when pumping the brakes.