An intake manifold leak is best determined by listening for a loud hissing noise that occurs when the engine is running. Discover how to use soapy water to confirm an intake manifold leak in a car with help from an ASE-certified mechanic in this free video on auto repair and maintenance.
Good afternoon. My name is Tom Brintzenhofe, certified master mechanic out of Reading, Pennsylvania. And today , I'm going to talk a little bit about what are some of the signs of an intake manifold leak. First, I want to start off and say, intake manifold leaks, the intakes themselves is not that common. Usually, the biggest problem you'll find is hoses. They get real bad. They get soft, and they end up blowing a hole in them and sucking air. The biggest way to tell if you have an intake manifold leak; the safest way to tell is, while the engine's running, you can actually hear a loud hissing noise. If you suspect you have an intake manifold leak and you don't hear anything, grab a bottle of foamy water, soapy water, and just spray it around on isolated areas along your intake manifold. And you should be able to, you'll hear when it starts sucking in that water. You'll feel a misfire, the engine will stumble, and that's the easiest way to find an intake manifold leak. Some of the signs of an intake manifold leak are basically rough idle, poor gas mileage, misfires going down the road, stumbling, hesitation. Other than that, that's about every sign there is to an intake manifold leak.