brake booster 85 300sd
 

This weekend I replaced the master cylinder on my 85 300sd.It was leaking internaly,causing the pedal to travel to the floor,but showing no signs of leaking.After installing the new master cylinder and bleeding the brakes,I took the car for a test drive.The brake booster is not working.Could I have made a mistake during installation?Could the booster have failed along with the m/c?I would be grateful for any help,ideas. :confused:

I am under the impression that if the master cylinder leaked into the brake booster that the brake booster is shot. Anyone? AM I correct???

Yes,.....unfortunately :(

thanks
 

thanks for the response.sadly,it makes sense

I bought a used one of e-bay for $11 - there is another right now and has a buy-it-now for $49. Much cheaper than the new price :eek:

I seem to have a brake leak some where. I believe it is the front passenger side. When I take the tire off and have some one press on the brakes while it is running I can turn the brake rotor with little to no resistance. But on the driver side it is impossible to turn it when the brake is pressed. There is no sign of fluid by the caliber's or anything. But the back brake fluid reservoir is loosing fluid. (I've been told the rear reservoir is for the front brakes). Also it seems I gained a new issue when the brakes quit well there just really soft and go to the floor now. Also when I turn the key off it does not want to shut off before it would shut off right away no problem. Do I have a bad brake cylinder and its leaking into the brake booster causing bad vacuum? There looks like there may be a slight possibility that where the hard line comes out from the frame on the passenger side it looks like it might of been wet but it's kind of hard to tell and I cant see how that line runs back to the master cylinder. I'm leaning toward brake master cylinder because It seems I've lost vacuum pressure but if I pull a vacuum line off I still fill sucking. Any advice is greatly appreciated. 85 300sd w126

There is a O-Ring that goes between the Mastercylinder and the Brake Booster. If it is not sealing well there it becomes a Vacuum leak.

The Brake Pedal going to the floor is a Master Cylinder or a leaking issue.

Brake Pedal taking a lot of force to brake is a Vacuum loss, Brake Booster Failure or stuck Calipers issue.

I was thinking possibly a new master cylinder. But how does it make since that the passenger rotor will turn but the driver won't when the brakes are pressed? That's what made me think there was a leak in the steel line running to the passenger side but I can't fallow it all the way because it runs threw frame and everything?

Entirely possible for the Rubber Hose going to one side of the Car go be messed up inside and blocking and holding pressure.
Or, the Caliper Piston could be stuck due to rust.

That Diesel911. But today I looked at car and in the wheel well of the passenger side there is a steal line that comes out and runs into a rubber line. Back right where the steal line comes out of wheel well the metal of the frame looks wet and looks like its getting wetter. How could I run a new line to the rubber line that hooks to the caliber. Where would I hook it up at?

this is what it looks like in the wheel well
http://s22.postimg.org/uvowxiegh/2014_03_23_14_07_26_623.jpg
http://s16.postimg.org/hp5yb2ncl/2014_03_23_14_07_42_722.jpg
http://s24.postimg.org/dzai029cl/2014_03_23_14_07_59_282.jpg
any help would be great. I dont know if i should run a new line from brake booster or if i can cut out some of wheel well and splice it on? Any advice?

do you know by any chance witch one of these lines run to the passenger front brake caliber.
http://s29.postimg.org/nz9m94jl3/brake_mb.jpg
There are other lines coming out of the box but I couldn't get them all in one photo.
Sorry for the continuous posts. This is my baby just trying to get her fixed.

Is there any signs of leakage around the car? One other thing to consider - Have someone look at (each)brake lines going to caliper while force is being applied to brake. Its not uncommon to have a brake line swell up (bubble).

My guess is a frozen rear caliper. If you tried to force the caliper piston in and it takes any significant effort then you need to replace. You will need to know which brand of caliper you have. I have the same car and had ATE, but some were also Girling. Replace the rubber hose at the same time. Yes booster is toast if MC leaked into it.