master cylinder question

[chucky07]

still trying to get brakes to work..and stay working...Okay determined for sure its not the line thats leaking afterall...I filled master cylinder and began bleeding brakes..The fluid is definately leaking from the rod that goes into the back of master cyliner (pedal pushes)...its leaking from that rubber boot thing all over...Does this mean it's a bad M/C? if so..is it a simple unbolt and bolt back on then bleed again?

thank you for your patience..just dont like doing things 4 or 5 times to get them right...

kevin

[carl b51]

Sounds like the rubber cups are bad in the master cylinder it will need a kit if the rust isn't to bad. There are 3 bolt that hold the master cylinder on and the brake line fitting. Oh ya if you need a Master cylinder Vintage power wagons have then for about 108.00 . I just did mine and changed to DOT 5 Brake fluid because it dose not atract moisture like DOT 3. Hope this helps Carl

[oldmopar]

If you rebuild the mc look inside and be sure there is no pit holes in the bore if there are you may be albe to clean it up with a brake hone also check that the bleed hole is clear. If the mc is pitted and can not be cleaned up then it needs to be replaced or resleeved,

Dot 5 should only be used for a new system where you replace or rebuild all cylinders (mc & wheel) I would also do the hoses, and also replace or at least flush lines with a break cleaner.

[MBF]

Ditto on what Oldmopar said. I know from experience that DOT 5 cannot be mixed w DOT 3. It will turn all the rubber goodies that are exposed to the mixture to a gummy mush. Things go pop when you least expect it! Found this out from the RAYMOND corp after their service techs kept replacing very expensive brake systems because they didn't know the two fluids are not compatible.

[chucky07]

well i order my master cylinder from NAPA on sunday..will be here tuesday morning..I figured i better not risk rebuilding my old one..besides I want whoever buys it to have good brakes..Gona flush old out of systemand just replace with Dot 3...i'm assuming that's whats in it now..wouldnt want to cause any leakes.

[Fernando Mendes]

I rebuilt mine GMC 1944 truck with a professional shop and it continues leaking in the back push rod of BMC.I only replace hydraulic fluid:p

[chucky07]

they should warranty there work and fix it for you..but I know what you mean..i use to have shops work on my vehicles..but I find working on them myself saves money..and i'll know it's right...

[grey beard]

It is my personal opinion that MoPAR master cylinders are not too dependable, especially after a rebuild. I have yet to find an old MoPar - either car or truck - that had been sitting very long and did not need a master cylinder. Maybe it's because of the location and the fact that they are prone to getting dirt contamination when serviced/checked.

I have rebuilt many master cylinders, and taught the process to many students. But in my opinion, rebuilding MoPar cylinders is a waste of time. I have bought several new units from Andy B - they're Mexican or some such offshore wonder - but they do work and seem to be dependable.

When you use a sixty-plus-year-old system, and it is just a single rather than a dual reservoir, you need all the security you can buy. Methinks brake master cylinders are not the most logical place to begin saving money. JMHO

Good Luick