Never rains but it pours. Brakes now. - PeachParts Mercedes-Benz Forum

pj67coll · #1 01-04-2020, 03:55 PM

So just a few days after getting my car thru emissions after a valve adjustment I'm driving it around the villiage and it seems to be running a tiny bit smoother with a little less smoke. Might just be my imagination of course but I'm feeling pretty good about everything. Pulling up to a stop and my brake pedal just smooshes to the floor. Bugger again. The thing is now like a soft rubber ball. Car still stops. In fact by standing on the pedal I even got the rear wheels to lock up. But it's not drivable like that. So now I have to tear into the darned brakes which is something I've never had success with before. It's what caused me to junk my previous one. Oh well. At this time I'm determined to get this fixed so hopefully. Really is agravating but I guess when car is this age and mileage you can't expect everyting to go smoothely.

- Peter.

TwoMuchBoost · #2 01-04-2020, 04:01 PM

Sounds like a leak in one of the front brakes. Front and rear circuits are separate so if you had a front leak, you'd push all the fluid out of front circuit and then somewhere around bottom of pedal travel you'd end up applying the rear brakes. I'm guessing reservoir is low as well?

pj67coll · #3 01-04-2020, 05:22 PM

Quote:

Originally Posted by TwoMuchBoost

Sounds like a leak in one of the front brakes. Front and rear circuits are separate so if you had a front leak, you'd push all the fluid out of front circuit and then somewhere around bottom of pedal travel you'd end up applying the rear brakes. I'm guessing reservoir is low as well?

Interesting diagnosis. The trail of brake fluid coming from the right front wheel and the way the inside of said wheel is bathed in the stuff would indicated that is the problem. The rear section of the reservoir is much lower than the front. About 50 percent compared to the front half which is at about two thirds.

- Peter.

dude99 · #4 01-04-2020, 05:51 PM

It would probably be wise to replace all the rubber Brie hoses at this point. Not expensive and since you’ll be bleeding them anyways.

Also, a pressure bleeder is worth the ~$50. Makes bleeding soooooo much easier. I honestly could never get a Mercedes to bleed the old fashioned way.

pj67coll · #5 01-04-2020, 06:12 PM

Quote:

Originally Posted by dude99

It would probably be wise to replace all the rubber Brie hoses at this point. Not expensive and since you’ll be bleeding them anyways.

Also, a pressure bleeder is worth the ~$50. Makes bleeding soooooo much easier. I honestly could never get a Mercedes to bleed the old fashioned way.

Yes. I'm going to have to do something drastic as I scrapped my last one when I replaced the Booster and couldn't get the clutch pedal to rise off the floor no matter what I did with the brakes. Most annoying but I refuse to be defeated this time.

- Peter.

Junkman · #6 01-04-2020, 10:44 PM

I would fix everything from the hoses going to the caliper and below. A lower fluid level in the rear compartment of the master cylinder confirms the leak in the front part of the system. The rear section isn't far behind unless it's recently been refurbished.

Remanned "loaded" calipers are not much money. You can buy low dust pads if you want and not have to clean the wheels every week or so. Replace all 4 calipers and hoses. You can wait to do the master cylinder if you want because it is relatively easy and can be addressed independently of calipers.

Repack and adjust the wheel bearings and buy new rotors if they are close to worn.

Some will say to only fix what's broken but these cars are old and neglected and different parts of a given system will fail sequentially causing you to be frequently wrenching unless the entire system is checked out.

pj67coll · #7 01-05-2020, 01:15 AM

Quote:

Originally Posted by Junkman

I would fix everything from the hoses going to the caliper and below. A lower fluid level in the rear compartment of the master cylinder confirms the leak in the front part of the system. The rear section isn't far behind unless it's recently been refurbished.

Remanned "loaded" calipers are not much money. You can buy low dust pads if you want and not have to clean the wheels every week or so. Replace all 4 calipers and hoses. You can wait to do the master cylinder if you want because it is relatively easy and can be addressed independently of calipers.

Repack and adjust the wheel bearings and buy new rotors if they are close to worn.

Some will say to only fix what's broken but these cars are old and neglected and different parts of a given system will fail sequentially causing you to be frequently wrenching unless the entire system is checked out.

Yes. Sound advice I think. I'm certainly going to look at doing both front brakes as I'm sure the other won't be far behind and I don't want to go thru all this again. Probably should think about the rear as well. Given that I have a problem in the rear end, likely an axle shaft, left side I think, it's probably time to take her off the road for a while and address a bunch of issues at once.

- Peter.

t walgamuth · #8 01-05-2020, 10:00 AM

I'd start with the basics.....I'd look and see where the leak is. It could be a loose fitting.

pj67coll · #9 01-05-2020, 02:25 PM

Seems the issue might not be the caliper after all. Looks like the inside of the wheel rim has cut thru the brake hose. I took some pic's and I hope I can upload them.

- Peter.

pj67coll · #10 01-05-2020, 02:27 PM

Ok. So it looks like I cannot upload the pics. But the brake fluid is sprayed only on the rubber of the tire, and a few inches up and downstream of the nick on the hose. No dampness anywhere else including the caliper. So I think I'll start by replacing the hose and hopefully that will be it.

- Peter.

pj67coll · #11 01-05-2020, 02:42 PM

Ok. Looks like I can post links at last. This is a look at the issue. Notice the dampness on the brake line either side of the nick in the rubber.

pj67coll · #12 01-05-2020, 02:46 PM

Looking here you can see some fluid on the sensor mounting but no dampness anywhere else. Also you can see the nick in the brake line and the wetness that ends a couple of inches downstream of the line. Looks like the caliper itself is dry.