When I press the brake pedal i hear a pop sound in the dash (possibly behind the ashtray area). Also if I am at light and I press the brake pedal all the way down the car act like it is going to stall. It does this when I am in park and just idling if I press the brakes a bit nothing happens but when i put extra pressure on them i almost stalls. It has never stalled but I'm just wondering what this could be.

It is a 93 240 sedan with about 250k.

 

Brake booster is malfunctioning.

Regards, Andrew.

 

do you think it is the brake booster itself or just the check valve? i looked online and the booster isn't too cheap. also is it something i should be concerned about driving? The brakes seem to work just fine as it is i just would hate to have it fail on me. It is something I will get fixed soon just how soon is the question.

 

Could be the check valve start there first cheapest and easiest. If it is a bad booster you may want to get a used one because they are spendy...safety wise I think you're ok. Good luck..

 

I gave you my opinion. The check valve merely stops flow in one direction, it is not the issue. You have a vacuum leak in the booster and probably caused by a torn diaphragm or defective shaft seal.

Regards, Andrew.