I have a 1992 Dodge D250 and has the huge master cylinder that leaks like every other one does. Is the a better option to replace it with? I have installed new/reman cylinders and they all leak the same place. Tried making new rubber inserts to seal it with mixed results. None of them cured it. Any advice is appreciated.

Are the 92s the ones with the aluminum body and the plastic top? Leaking at the seals between the plastic & the aluminum? The early 2 piece masters worked pretty well, but they have probably been "upgraded" to the newer seals that are not worth two hoots. It seems there was about a 3-4 year window where the masters didn't seal well. earlier or later ones seemed a bit better.

I think the older one piece cast masters will bolt up to the booster, you just need to get one with the correct number of mounting bolts (2 or 4). I'm thinking the early 80s trucks have what your probably looking for.

I'm also having a lot less trouble with the mid 90s Dakota masters, they seem to seal pretty good. Gene

Fyi, on trucks in that era, they used 2 master cylinders, light trucks got the aluminum and plastic cylinder, higher gvw got the big one piece cast iron one.

Op, you sure you're not over filling the master? Should be a quarter to 38 inch from top.

Mine is the huge cast iron unit. The master cylinder will run itself dry no matter where I keep the fluid level at. No leaks in the rest of the system.

my '91 W250 Cummins had the big cast master, seems to be a common problem with that type leaking, mine sure did.

Ok, ill bet you have the same problem i do. Im not leaking fluid anywhere but, its transferring from one reservoir to the other.

I cut a small notch between reservoirs, whizzer wheel about half inch deep in the divider.

Oddly my 92 is the only one that has ever done it and does it with different master cylinders. I suspect its bypassing through the safety switch.

Are you actually losing fluid with no visible leaks?
If it's running itself dry, it is going some where.
It might be going into the booster from the back of the cylinder.

Not good.

Might want to take a peak.

Are you actually losing fluid with no visible leaks?
If it's running itself dry, it is going some where.
It might be going into the booster from the back of the cylinder.

Not good.

Might want to take a peak. [/quote

I had one doing that and it was leaking out the back down inside the firewall,like was said it's going somewhere.

It leaks all around the seal between the cap and cast iron body. Frame rail on that side is constantly wet.

Sorry,I thought you didn't know where it was leaking.

Take that rubber gasket out of the cap & clean up all that embedded rust so it looks new again, then carefully use some scotchbrite on that upper lip without getting it in your fluid. Its worked on many of my trucks with that style master cylinder

This has turned out to be the fix so far anyway. Yes, made in China but it is brand new. No leaks for 3 months now. Time will tell. I will never buy another reman unit again.