Hello Everyone,

My MC appears to be leaking into the vacuum booster? When I pump the brake pedal, I have no pressure as if air were in the line, and brake fluid sprays out of the brake booster. I've replaced the master cylinder (duralast part) three times with the same result.

I've run out if ideas on the issue. Could add pictures, or a video later if that helps.

 

You could be getting bad ones. Did you bench bleed the master cylinder?

 

Could be also that the original one leaked into the booster and the new ones aren't bled properly. Result is no pressure and the booster is still spitting the old fluid out from the first MC. Does that make any sense? Two issues essentially unrelated?
Get the MC bled and remove the booster and try to clean it out.
Or might try biting the bullet and getting new MC and booster from Napa.

 

I don't believe the fluid coming out of the booster is a residual effect? I was actually going to try a different brand MC this weekend. Also, I bench bled the original MC, but not the following two, as I did not believe the fluid coming out was related.

 

You have to bench bleed any new master cylinder, or there will always be problems.

If they are leaking fluid into the booster, then they are bad. Duralast is not know for their quality......

If the booster has enough fluid in it to be spraying it out, it's time for a new booster as well. Brake fluid will destroy the diaphragm.