| sluggo |
Tue Nov 08, 2005 6:27 pm |
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I've got a new Brake Booster. I want to make sure my master cylinder is good before I put it back. How would I do this. It looks okay. A little corrosion around the piece by the o ring but that's it. It actually looks pretty new. I know the PO was dealing with the brakes and being true to his half ass work could have replaced this and not the booster. I know he didn't bother with the 30 year old hoses.
Here's a few pics.
That little bit of fluid is from me (that sounds kind of gross).
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| steponmebbbboom |
Tue Nov 08, 2005 6:29 pm |
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| Did the pedal sink to the floor? Was the pedal abnormally low all the time? If not you should be ok, for now. |
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| sluggo |
Tue Nov 08, 2005 6:37 pm |
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steponmebbbboom wrote: Did the pedal sink to the floor? Was the pedal abnormally low all the time? If not you should be ok, for now.
The pedal is perfect. In fact, quite high. Never had a problem with losing fluid either.
That "for now" statement bothers me. Are there other signs I should look for? |
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| BIGTSV |
Tue Nov 08, 2005 6:55 pm |
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| Most of the time it will start to leak, my 73 leaks allot and as long as it is full it seems to work. If it sarts to leak or the pedal starts to drop, keep fluid in it an plan on changing it soon. |
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| steponmebbbboom |
Tue Nov 08, 2005 7:02 pm |
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| No one can guarantee the longevity of a used part. All you can do for now is change the fluid once a year and wait for the other shoe to drop. |
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| sluggo |
Tue Nov 08, 2005 9:51 pm |
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Cool. Thanks. I just put it back on with the new booster. I'll keep an eye on it but It seemed like it was rebuilt recently. All clean except for the part that enters the booster. Even the rubber seemed new.
I saw somewhere that you should put a gasket between the booster & cylinder. It didn't come like that but it was suggested on this site. I just cut a Weber intake manifold gasket to fit. |
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| Karl |
Wed Nov 09, 2005 7:41 am |
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You don't want a gasket between the booster and master, you want a nice NEW O-ring there. The o-ring seals the vacuum leak.
#16 here: http://www.ratwell.com/technical/Microfiche/t205000.gif
The gasket, #4, is for NON servo [booster] equipped buses, 68-70. |
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| jereandjess |
Sun Mar 30, 2008 12:25 pm |
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Anyone know a part number for the o-ring Karl mentions?
Do I need anything particular or could I just find a same sized one at the hardware or plumbing store? |
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| RobWeidman |
Sun Mar 30, 2008 1:48 pm |
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You can test a master cylinder either installed or on a bench. Either way get a section of spare brake line with the proper size fittings and cut the line (short) and bend it over and crimp it a few times onto itself. Then, connect the fitting to whichever circuit you want to test. Perhaps you want to test front and rear at the same time, or one versus another. It doesn't really matter, unless you 're trying to rule one circuit out.
Ensure that there is ample fluid being provided to the master cylinder. When the pedal or plunger is depressed, you should get solid resistance - not sponginess. Sponginess indicates either air in the lines or lack of master cylinder integrity. With such short lines, air is unlikely.
In my experience if you test this on a vehicle your pedal will barely move when the test connections are made. And you will smile. . . |
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| Karl |
Sun Mar 30, 2008 2:39 pm |
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jereandjess wrote: Anyone know a part number for the o-ring Karl mentions?
Do I need anything particular or could I just find a same sized one at the hardware or plumbing store?
It is a square cut O-ring. Size is 41,5 x 2,5mm.
VW part number 357 611 243
Or go to your Mercedes dealer. Same seal ring. Mercedes part number
004 997 32 45 |
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