Master cylinder "leak hole"? - PeachParts Mercedes-Benz Forum

wolf_walker · #1 03-20-2004, 09:45 PM

This may well be a stupid question, but a brief look at my books, the FSM and otherwise, give me it's name and nothing else. I also searched..

So, what the heck is the "leak hole" near the booster side of the master cylinder? Mine seems to leak a bit when brakes are applied, and has been doing this for awhile from the look of things. I flushed the brake fluid today and noticed it, brakes feel perfectly normal.

Please advise, thanks...

And yes I know it's a "leak hole" is "a hole that leaks"..

:p

whunter · #2 03-20-2004, 10:54 PM

Hello wolf_walker
A picture with an arrow indicating area would really help.
The area you refer to; tells me that the master is going bad.
If any fluid is leaking out of the master; I would replace the master.
This is a safety issue; replace it now, do not wait.

wolf_walker · #3 03-21-2004, 02:18 AM

This is quicker..

Item A is leak hole..

http://skinnerbox.steaky.org/123_DISK2/program/Chassis/42-315.pdf

I'm assuming it's much like the weep hole on a water pump, that the rear most seal is leaking and fluid is being pulled past it from the vacuum in the booster, or pressure of brake application, either way.

Now can I put a seal kit in this thing I wonder, the FSM seems to think so..

This is really completly unfair to be doing routine, timely maintanance like a good guy and find a problem like this. Completly unfair.. Oh well, such is life..

wolf_walker · #4 03-21-2004, 02:54 AM

OK, I find reference to this being done, such as here..

http://www.peachparts.com/shopforum/showthread.php?threadid=45741&highlight=master+cylinder+rebuild

But none of my usual parts places seem to have a kit available?

I don't plan on driving this car more than another year if that, I'd really like to just put a kit in this thing..

whunter · #5 03-21-2004, 10:45 AM

Master cylinder rebuild kits are becoming hard to find.

Too many people do not know when NOT to rebuild.

You are risking your life, any passengers and other innocent people on the road.

Part # N3000-12247 Brake Master Cylinder $83.83

FastLane http://catalog.eautopartscatalog.com/mercedesshop/wizard.jsp?partner=mercedesshop&year=1983&make=MB&model=300-DT-001&category=N&part=Brake+Master+Cylinder

wolf_walker · #6 03-21-2004, 10:54 AM

It is a risk, but with a perfectly functioning master cylinder, and if I do not observe any defects on the pistons or cylinder wall and they mic to spec in and out, I see no reason not to just put a kit in it. Especially being that I don't plan on driveing the car another year. Quietly hunting a w126 for my driveline to be put into.

I took and passed those ASE brake tests that were mentioned in the other thread too, just never had all the varifiable years in a shop to back it up..

Still hunting the elusive kit..

compress ignite · #7 03-21-2004, 04:01 PM

WW, Just in case YOU do rebuild M.C. and someone else re-
habilitates the 126 after you canabalize it (and it causes my
demise in an accident) What's the V.I.N. on your 126??????

compress ignite · #8 03-21-2004, 04:07 PM

Am I human? ....Your Car is a 123 series
Could you be contemplating , making a mistake ....also?

psfred · #9 03-21-2004, 04:09 PM

If the brakes "work fine" you have a minor wear problem with the piston seals and the pushrod seal is shot.

Replace or rebuild -- if the bore is clean, the seals just died of old age and a rebuild will fix you right up.

Anything but new looking honing in the master cylinder bore, replace.

Peter

wolf_walker · #10 03-21-2004, 04:51 PM

Quote:

Originally posted by compress ignite
Am I human? ....Your Car is a 123 series
Could you be contemplating , making a mistake ....also?

What exactly are you rambling about?

Look in the FSM, if Mercedes did not intend the seals to be replaced in the master cylinder, there would not be several excellent pages detailing the procedure.

I've put seal kits in at least a dozen MC's, they were all fine. This is not rocket science. If I'd been asking about a caliper kit nobody would be bothered in the least. Needing new seals after a quarter million miles and the actual bore and piston showing little to no wear due to proper regular fluid changes is not all that surprising to me. I've done it with fords, chevys and VW's, why not a Mercedes? They are afterall god's gift to the automotive world are they not? Jesus christ..

psfred, that was my evaluation of the situation. I just can't believe that so many people that drive two decade old Mercedes diesels are grumpy about the idea of rebuilding something instead of just replacing it. I really don't get it.

psfred · #11 03-21-2004, 05:27 PM

A lot of shops have gotten burned on brake work liability, so they only replace with new or warrentied brake parts to avoid sky high insurance problems.

If you do find a rebuild kit, it will contain ALL the guts -- all you keep is the cylinder itself, all the pistons, springs, seals and retainers are in the kit.

If you can't, replace the master cylinder, they aren't that expensive compared to no brakes.

Peter