The brakes on my car are very stiff at start up. After I stomp on the brakes one time, they work fine. I have been told by a mechanic that I need a new vacuum assist pump and check valve. It will cost $700 parts and labor. I've read that this is a common problem on Volvos of this age. The mechanic said if I don't get it fixed I should NOT DRIVE the car because it is not safe because brake failure could occur. My question is, what is the function of the vacuum brake assist? I understand it is supposed to kick in when the engine does not provide enough vacuum for the brakes to work. Does it only need to function at start up? If so, I am happy to save $700 and stomp on the brake pedal before I drive somewhere. However, I don't want to be driving down the freeway, need to stop suddenly and have the brakes not work. Thanks so much for any help and explanations you can provide.

 

The brakes will still work even with no vacuum but you will have to mash on them much harder than with the vacuum assist working properly.

Now you said the brakes work properly after startup once you mash the brake pedal once? I have read of this problem before. Try searching the forum for vacuum pump problems. I believe there is a solution not involving replacing the pump. (RockAuto sells the pump for $101 just in case)