brake master cyl - PeachParts Mercedes-Benz Forum

funola · #1 09-01-2009, 11:47 AM

I been having lots of brake problems lately. I put in 2 rebuilts from Autozone and the second one is giving me a sinking pedal again. I picked up a used OEM master cyl which is supposed to be good when it was removed and it is aluminum! I thought master cyl are usually cast iron? Anyway, I think I am going to give the aluminum one a try. Anyone know if the bore is also aluminum or does it have an iron sleeve?

Diesel911 · #2 09-01-2009, 12:12 PM

I have had Aluminum Master Cylinders on my car befor (Olds Cutlasss). I believe they just have an Aluminum Bore as do Aluminum Wheel Cylinders for Drum Brakes.

It is easy to check. Just suhove the Piston/s in manually till you can see the bore or remove the Rear snap-ring and washer (could be a 3 cornered wire retainer spring) and take a peek at the bore. If it has a steel bore it should go all the way to the open end of the Master Cylinder.

Diesel911 · #3 09-01-2009, 12:26 PM

I also had a problem with a rebuilt Master Cylinder (bought from Kragens Auto Parts abd rebuilt by Cardone) and drove 1-1/2 years with a spongy pedal.
Finally the Pedal went nearly to the floor.
At the time I did not know were the paper work was to warrant the rebuilt MC. I decided to buy a new one which at that time Autozone sold for $60+ made by FENCO. That solved the problem.
Unfortunately when I looked up the AZ price for your 83 the new ones are now $86 each.
Later I found the paper work and exchanged the rebuilt one; and I guess I have a spare one. I hope the rebuild on it is OK so I can use it later.

funola · #4 09-01-2009, 02:16 PM

There is a shaft sticking out, not a recess into the mc, therefore the bore cannot be seen without taking the circlip off. I didn't have circlip pliers so couln't look inside. I did put a magnet around various parts of the alum body and certains areas inside were magnetic, but it's hard to tell what those ferrous parts are without disassembly. Anyway I have the used alum mc installed and flushed/bled the system and the pedal feels good. I'll have to wait and see if it stays that way.

I actually ordered a new Fenco from Autozone #034922 NM52326 comes with reservoir and the price is 65.99. I think prices varies depending on the store you buy it from.

funola · #5 09-01-2009, 04:02 PM

The new Fenco mc came in and look exactly like the 2 Fenco rebuilts I've had so I got my money back on both the new and rebuilt. Autozone was nice enough to give me a free bottle of Valvoline synthetic brake fluid for my troubles.

lupin..the..3rd · #6 09-02-2009, 11:20 AM

I would never buy a rebuilt master cylinder. For this particular part, I always buy new. All the rebuilt's I've seen are very low quality.

winmutt · #7 09-02-2009, 12:41 PM

Are you bench bleeding? Try the Cardone's.

leathermang · #8 09-02-2009, 01:25 PM

I believe the most common interior sleeve for something like this is brass....
So a magnet would not detect that either...
In the past rebuilding of really old cars regularly had brass sleeves installed to get them back on the road... done right it is just as good as new.
Proper Bench bleeding and then Proper regular bleeding is very important...