Real quick: There should be a gasket where a master cylinder meets the firewall on a car such as my Cutlass, correct?

Today I got a new master cylinder, the root of all of my brake woes, and the leak is still there. When I removed the old master cylinder, there wasn't any gasket in the area I've described, so I'm leaning towards no as being the answer to my question, but I still have some cause to think a gasket might go there.

Edited September 26, 200817 yr by YellowJacket894

A quick poke around the net doesn't show any installations or rebuild kits with gaskets that I found, nor does a search for 'master cylinder gasket' turn up anything that shows one thru the first 7 google pages. There wasn't one on my B-59's 'single pot' unit... but your '72 is a bit new for my hands-on experience ('50s thru '60s).

I assume your 'leak' is brake fluid, then, as opposed to water entering the pass compartment? Is the new unit a remanufactured one, or a new one? Was is made in China?

Where is the leak coming from? If the leak is at one of the lines entereing the MC, you may have a cracked seat on the line end, and will need to bend up a new one. Ready-bent lines are no doubt available thru resto sources- a Chevelle catalog should have one.

Was there a return on the old MC? If not- hang on to it. It's far more recommended to rebuild the orig than take a chance with the Chinese crap in most parts stores these days.

I've found the source of the leak. The new master cylinder has a bad internal seal, which will have to be fixed for about 15 bucks.

holy Cow, where have I been....? you're rockin' a classic,V8-powered, RWD, BOF Oldsmobile hardtop!?.

Congrats Dude!!!

holy Cow, where have I been....? you're rockin' a classic,V8-powered, RWD, BOF Oldsmobile hardtop!?.

Congrats Dude!!!

Thanks, Sixty-8.

And after getting the Cutlass, I'm really starting to think that there's actually a lot to the whole "new cars suck" thing. I'm already giving some thought to somehow getting another classic of a similar vintage to the Cutlass to replace the Sonoma (read: Chevelle or LeMans). I will most likely wait for a few other things to flesh themselves out before I start thinking seriously about doing this, though.

YJ, no there isn't a gasket there, sometimes a master cylinder will have that semi-covers and seals the area between the master cylinder and the booster, but most of the time, its just a straight bolt-up application.