Yikes! No brake booster / other nasty issues! - PeachParts Mercedes-Benz Forum

Zerohour3k · #1 07-25-2007, 09:28 AM

Okay, I don't usually resort to the "HELP!" type of post, but I was in for one hell of a scare this morning...

I woke up late for work, and in typical Jersey fashion, drove 95 mph down the Parkway until I got to my exit. No problems, brakes worked fine, etc. As I'm sitting in traffic on the exit ramp, I notice that I'm creeping up on the guy in front of me a bit *too* fast, especially since I'm hitting my brakes! After romping on the pedal pretty damn hard (so that I stopped... slowly..), I realized that my brake booster has either broken, or is no longer getting any vacuum.

This was all confirmed when I got to work, mashed the brake to get into my parking spot.. turned the car key off, and.... nothing. Engine keeps going until I hit "ye olde lever". All the lines seem to be in good condition, and the brake booster worked like new, no more than an hour ago. Is this a vacuum pump problem, or can a brake booster actually fail this quickly, causing me to lose the engine-off ability, as well?

Most importantly... aside from the obvious braking issues (manual brakes, ugh!), is it safe to drive the car? A failed vacuum pump / check valve won't damage the engine, right..? Right..?

...this is just what I needed..

winmutt · #2 07-25-2007, 09:56 AM

Check the master line running from the pump to booster for cracks. If there is You might limp home with some decent tape or super glue (just make sure it dries). For both interior and booster to fail I believe it is wither tha vac pump or the line. Someone else chime in.

Safe? Not really. Not that it has ever stopped me. Go real slow and allow for PLENTY of stopping. Pray you have some brake compound left on your parking brakes. Be prepared to use them.

I take no liability for the above statements. Proceed at your own risk.

toomany MBZ · #3 07-25-2007, 09:57 AM

Yikes is right! I don't know if a vac pump gives up the ghost like that or not, but it wouldn't surprise me. The only problem you have is what you have found out, maybe poor shifting, no door locks too. No engine damage will occur. German engineers love to have stuff run off vac, hence the pump. Check as soon as you can, of course. Good luck.

Zerohour3k · #4 07-25-2007, 10:08 AM

I didn't see any cracks, but then again, I wasn't looking intensely at the line. From what I saw, it looked like almost-new rubber, but I could be wrong...

I thought it may have been the center vacuum pod for the ACC, since the center vents only blow 90% of the time (the other 10%, they kind of "stick", and I have to toggle the ACC to "off" before they'll reactivate).. but this issue happens even when the ACC is off, so I doubt that's the problem..

Meh, why couldn't it have been something less important, like a broken seat spring, or a bad relay...

Zerohour3k · #5 07-25-2007, 01:16 PM

Update:

Had a local mechanic take a look at the V-pump and lines, to see if I overlooked anything. Upon removal of the main vacuum line, he quickly diagnosed the problem.. my check valve is gone. Disintegrated. Vaporized, not there, gone. Apparently during my 85+mph commute, the thing fell apart, I guess.

He doesn't guarantee that it's just going to be the valve, and that it *COULD* be the pump itself.. but the valve is a place to start. My question therefore, has changed..

"Is it possible for the car to have working power brakes, etc, without a check valve in place?". I'm guessing it kinda-sorta does, since after re-attaching the line to the pump, and driving off, the brakes seemed to work normally. Check valve will be replaced tomorrow, since it looks like an easy job. I still have to wonder if all these problems could be caused from a check valve that fell apart...