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1991 190E 2.6 Auto, Artic White/grey MB-Tex
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278 Posts
Discussion Starter · #1 ·
I'm having issues with my brakes. When your 190E's engine is off and you press the brake pedal a couple of times, does the pedal become progressively firmer or does it go down the same each time? After you've pumped the pedal a couple of times and your foot is still pressing the pedal and you then turn the engine on, does your pedal drop a little?

THANKS!
 

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'98 E300, '10 GL350 Bluetec
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1,265 Posts
That sounds quite normal; when the engine is off and you press the brakes, you are using up the vacuum reserve in the booster. After a few times you have run out of vacuum and the pedal is very hard to press. That is why the pedal action gets progressively harder.
When you start the car with the pedal pushed down, the vacuum builds up and assists your leg in applying the brakes, so you can 'feel' it go down a little; in fact, it is probably the feeling of the assist taking the effort away from you.
 

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1991 190E 2.6 Auto, Artic White/grey MB-Tex
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278 Posts
Discussion Starter · #3 · (Edited)
That sounds quite normal
Exactly, every car I've driven does it, EXCEPT MY CAR. I thought maybe what car my is doing (pedal doesn't get very stiff when pumping it with engine off) is characteristic of 190E's in general. You didn't mention if you car does this. Does it?
 

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W245 Moderator
2009 C300 4MATIC
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3,302 Posts
Jim, your vacuum check valve (the big one on the hose from the intake) for the booster might be going (rarely the diaphragm goes) so you might loose some vacuum there.
 

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1991 190E 2.6 Auto, Artic White/grey MB-Tex
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278 Posts
Discussion Starter · #7 ·
Holy crap! I must build a "measuring connection?! I thought you could blow on one end of the valve and see if it passes air or not.
 
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