Hello,
The brake pedal has been "pulsating" for the past few months at slow speeds (0-10 mph) when the brake is applied on my 87 300D turbo. I am assuming that my sensors are dirty, but my shop manuals do not mention anything about them, leaving me to assume their is a separate Mercedes manual for ABS systems.
Can someone give me a little help in locating these?
Also, I am a new member here, I used to get alot of information from the "diesel.org" site, I have not been able to get any posts or lists from them lately, anyone know what happened to that forum? Anyone know if the "archives" have been saved from this forum?

Thanks,

Richard Fine

 

Welcome...

I drive also an 87 300D and have been down your road, chattering brakes at every stop. At first, I thought I had a faulty sensor and had read that they can get dirty and can cause this chattering. There are three ABS sensors with one serving both rear wheels located on the right hand side of the rear differential, or pumpkin, as some like to call it. The other two are located on, or near the front of the brake calipers.

I have removed all three and cleaned them, also I cleaned the splines in the wheel hub, and no difference!

Someone on another benz forum suggested that what was causing the ABS to chatter, while coming to a stop, or below 5 mph, was in fact a frozen brake caliper piston. There are two hydraulic pistons to each brake caliper.

I bought a rebuild kit for both front calipers. When I got the calipers off the car and onto a bench to rebuild, I discovered that one of the pistons in the left front caliper had seized.

Instead of replacing the whole caliper, I decided to rebuild it, even though the chrome plating had corroded in a few areas, but my big problem came when I tried to replace the rubber boot that covers the piston. For me, it was impossible to get these new rubber boots on and so after cleaning up the pistons, installing a new seal, I left out putting any boot back on knowing that in time this caliper would once again need attention.

After putting the calipers back on last spring, no more chattering. This proved that the sensors were not at fault and as I predicted, my brakes just this past week are beginning to chatter again, AND, I'm feeling the beginnings of warped rotors, a tell-tale of caliper failure!

While you are doing calipers, and I think this is your problem, do a complete flush of brake fluid too. You should be changing that every 2 years anyway!

Here is a link to MB service manuals, free on-line! http://mb.braingears.com/ or http://skinnerbox.steaky.org/service/w124/main.html