So I've recently purchased my first car. It's a '77 Maverick. Two days after I bought it the brakes began hissing, that was approximately 4 weeks ago. It has increased to hissing brakes, a rough idle, and sometimes the idle is so rough that the engine dies. When I put it in park or neutral the rough idle ends so I think it's a vacuum problem but I can't find the leak. A friend of the previous owner suggested that I check behind my brake booster. Any other suggestions?
There is a check valve on the booster, its were the hose connects to. Check it. When mine when bad it did all the symptoms your car is doing. Fixed it and the hissing/vacumm leak was cured. Good luck and welcome to the maverick universe.
It was the booster. Since I can't afford a new one right now, and I don't have the time to replace it right now anyways, I just put a $3 battery bolt in the vacuum hose and clamped it off. I told myself I'd replace it later but I probably won't anytime soon. My brakes are a good deal harder to press, but it beats having to re-start my car at every stop sign and red light.
