Chasing a vacuum leak on my 91 Civic took me 6 months

I kept hearing this weird hissing noise under the hood and the idle was all over the place. Replaced the intake gasket, checked every hose I could see, even sprayed starter fluid around but nothing changed. Turns out it was a tiny crack in the plastic intake manifold right where it bolts to the head, only visible if you took the whole thing off and held it up to a light. Who else has spent way too long hunting down something that simple on a cheap build?

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schmidt.grant2mo ago

Man I had a buddy do the same thing on his old Celica, spent almost a whole summer chasing a vacuum leak that made the car stall at stoplights. He replaced the fuel filter, the distributor cap, even the whole throttle body gasket set. Finally his dad came over with a length of garden hose, put one end to his ear and ran the other end along the manifold, found the crack in like ten minutes. It was this hairline split right under the EGR valve, you couldnt see it unless the manifold was off and you bent it a certain way. We all felt pretty dumb after that, but sometimes you just trust the obvious stuff before you start pulling everything apart.

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river_hart182mo ago

Nah man that's on you for not checking the manifold sooner. 6 months of chasing a hiss and you didn't pull the intake off day one? Easiest way to find stuff like that is just take it apart and inspect it, not spray starter fluid everywhere like a YouTube tutorial told you.

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