I poured the seafoam in the brake booster its been about two weeks now NY brakes are going to the floor and hissing what should I do
My car has an automatic transmission.
Hello, the brake booster assembly will have to be replaced. There are rubber diaphragms that degrade from seafoam. The hissing sound is a vacuum leak with the booster. I recommend having a certified YourMechanic technician come to your location to replace the brake booster.