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My replacement ac Delco gold does not have the rubber gasket as the original has. does the old O-ring gasket have to be used for mine is torn ? I can not find a replacement part number as per assembly. . instruction manual. Part number 730392 gasket
I don't have one on my P/B car and don't have any issues. There isn't a need for it to seal vacuum, so I'm not sure its purpose other than to trap leaking brake fluid so it rusts out the brake booster. You could use a large o-ring of the proper OD/ID dimensions to fit the groove, which should be pretty readily available at a decent hardware store in the plumbing section.
#2 is the gasket you asked about, #3, I believe is just a foam ring.
Last edited by barkingrats; Jul 8, 2025 at 12:24 PM.
Like said, don't really need it.
If you insist, lay down a circle on a piece of glass with a tube of silicone and let it dry.
Razer blade it up, should work.
Thanks for all your suggestions,CSSB said i was second person to acquire about seal.and the need was to catch fluid which could contaiment boosters seal may be.
1977 master cylinder replacement
