Missing bolt in the intake = vacuum leak?

88WhiteGTConv said:

Well ive been trying to find out where my vacuum leak was coming from. I did the usual spray carb cleaner everywhere but that was helping. So i decide to tear the intake off the car and make sure the gaskets are sealed. Well when i went to take the upper intake off i noticed that the bolt under the TB was not tehre?!?!? the last shop that worked on my car forgot to put it in i think, and my car hasnt ran right since...thats another long story with legal troubles involved. But anyways. Could that missing bolt cause a 5psi drop in vacuum by itself?

Mike

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I don't know how much loss it would cause, But I do know you want all your bolts in. I believe the upper and lower intake bolts are 7/16, so take one of your other bolts to Lowes and get another and that way you'll have all of your bolts. I'd pull the upper and replace the gasket and bolt it back down. Be sure to label those couple vac lines in back. Good luck. You prob. could just throw a bolt in there and be done w/ it, but I'd personally just replace the gasket. Be sure and torque properly...I'm thinking 18 lbs, but I can't remember

Um, I would say yes. There aren't a lot of bolts holding that thing down, and depending on how the engine rocks and shakes, the leak could be better at times, and worse at times.

At the same time, all the vacuum hoses under the intake are probably cracked and messed up, so you should change as much as you can while you have the intake off. All 3 of my friends and my car had cracked, groddy hoses that disintegrated when you pulled on them.

Just handtighten the upper/lower bolts...the intake can crack fairly easily...10-12 ft. lbs is all you need...

My intake bolts for the lower and upper were 1/2"...

I doubt it would cause a leak that "drastic" if at all...as long as it is laying on a flat "true" surface...you should be fine...but get the bolt/nut on there...

The only questionable vaccum line that could be "messed" up under normal wear conditions is probably the carbon canister hose (front left) of the intake...and it runs to the passenger side...all my other hoses were like new except that one...the heat kills the components on that hose...