why is my brand new master cylinder seeping?

[1980c10]

btw; if the master cylinder leaks out of the back it needs to be replaced, if you dont the brake fluid will get in to the booster and ruin the diaphragm and you'll need to replace that as well.

[beastie_3]

So to upgrade, you need both the booster and master cylinder for a 85? Is there any braking benefit from upgrading, or is it just looks/style?

[1980c10]

The newer booster is physically bigger and the top doesn't leak on the master. My brakes felt fine with the older style as well. So I don't really know if the newer style better or the same but the fact that it doesn't leak and looks better was enough for me.
-The 85 master would not bolt up to the 80 booster. I had the 85 booster so I installed that as well.
This is an easy salvage yard find as long as there are no signs of leakage.
I consider it a nice little improvement for little money and little effort. It was a good time for me to re-do my brakelines as well.

[txchainsawgogi]

so is there a direct fit plastic reservoir replacement for a 1978 2WD 350 c10 silverado? i cant seem to find one. will another year bolt up ok or am i stuck having to go find a booster from an 80's blazer?

[1980c10]

I think it would be easier to just find a newer booster than trying to find something aftermarket and if you needed to replace it in the future it would also be nice to pick one up locally. These are not hard to find and you can buy them new if you choose. I think the boosters are about 99 and the master cylinders are about 40.