1965 190D W110 Brakes/Master Cyl

[DrCherry]

Took the tractor for a test spin with my freshly bled clutch and at the first
stop the brake nearly went to the floor. I found I had to pump it to get the car to stop fully. A half block later, same thing. Two pumps to get enough pressure to stop.

Took it back into the garage and shut her down. I found when I pumped and
pushed, I could hear a hiss somewhere. As if air was escaping the system.

So it looks like a brake job for me. I have a brake booster which accepts a
vacuum line.

How far should I go on this? Any tips on hunting down the hiss? If this isn't
obvious, I'll go through the whole system.

Pelican Parts sells a Brake Booster Bushing and a valve check, not
sure where the bushing goes but I figured I'd replace it "while I'm in there".
I found it odd that they sell all the parts to rebuild the slave cylinders but
not the master cylinder.

My thinking is to start with the Master Cylinder and then go from there. Any
advice is welcome.

[KCM]

Sounds like you have two different problems. The hissing is likely a slight vacuum leak in the booster, but would not cause your brakes to go to the floor. The bad booster likely would cause the pedal to get hard rather than go to the floor. Sounds like you might have a bad master cylinder, leaking wheel cylinder, air in the system, or a combination. I wouldn't worry much about the hiss as a small leak may not be a big issue. I have a non-Mercedes car that has a slight leak when you press the pedal, and has for years, but does not affect the brakes.

First thing to do is to look for leaks at the wheels. Wheel cylinders are known for leaking, especially if a car sits for an extended period. Wheel kits or cylinders may be needed. Then try bleeding the wheels to make sure there is no air in the system. If that doesn't work, I'd bet it is the master cylinder.

[newtodiesel]

Let me first start by saying I have a 1985 and have no clue if your vehicle
is anything like the 85.
But on mine there is a bushing inbetween the master cylinder that goes into
the brake booster, in the 85 it is commonplace for this bushing to go bad, might be worth investing in a $1.00 bushing to see if it will fix one problem.

Post some picts of your car please. Looks like a real nice one.

[DrCherry]

I will be replacing the bushing on the booster when I do the master cylinder. I'm going to replace the rubber hoses and very likely the master cylinder.

In the middle of this work our 02 VW Jetta took a dump on I-75 so I ran out and bought a very cheap, fairly beat '80 240D. As if I didn't have enough on my plate.

So I'm now trying to diagnose the right-front caliper which appears to be not retracting fully. I don't think there's any way around getting out the breaker bar and taking it off for inspection.

Here are some photos of the 190D

Heckflosse - DefcodeWiki

[shadetree77]

love the back of that W110; it just screams 60's...

[DrCherry]

Benz designers claimed they were to "assist in parking".

[newtodiesel]

For the 240, just go to the mcparts store and get a new set of calipers and change out all the brake hoses and flush out the fluid, its probably black anyway
The calipers are probably rusted you can sand the cylinders lightly once you fight them off and maybe get them to work again, but with all you have going on just replace them new in pairs, but I am sure you already knew that!.
My free opinion

I was told the same thing when mine did the same thing, but flushing the fliuds and changing the pads fixed my problem. Make sure you soak the bleeder screws a few days before attempting to use them or else they can and will break off.

WOW that finny is really nice..how did you find it? Can I suggest one thing???
New different color dashmat???
purdy purdy

[DrCherry]

The 240 needs everything. The brakes are currently working so my list goes something like 1) change all fluids starting with oil 2) diesel purge 3) track down engine oil drip.

I have my work cut out for me, this 240 was cheap but it's a bit of a mess.