1990 240sx power brake booster testing

[rpb_2007]

The brake pedal on my son's 1990 240sx is hard as a rock. There's also a sucking sound coming from the power brake booster. I'm assuming that he blew out a seal in the booster during hard braking. Is there a way to test the booster before swapping it out? The pedal won't compress when I removed the vacuum line and sealed the vacuum inlet. The pedal compresses easily when I separated the master cylinder from the booster.

[180fan]

booster issue.

[benemorius]

Yup. Make sure you get a replacement from Nissan and not a parts store. I'd even recommend a junk yard unit over something from a parts store. And don't go blaming your son for it. "Hard braking" didn't kill the booster. You might check to be sure that the master cylinder isn't leaking brake fluid into it, though.