How do you know what is a vacuum line under the hood when you were told you have a leak in it but not sure what is vacuum lines?

A vacuum line or better yet a vacuum tube is about a quarter inch hose, black and very flexible. You will find at least 6 of these hoses located under the hood going into and coming out of many different places. These hoses have suction when the engine is running. If a hose is unplugged from its place, it could cause a number of things to operate differently. How to find a vacuum leak? It�s not easy if you don�t have a good eye and a good ear. Look for opened tubes or unplugged nozzles where the hoses plug into or come out of. If you spot one- then put your ear close to it to notice a hissing sound coming from it. Of course be sure that the engine is running and be careful of moving and hot parts. After searching for open tube ends and listening for hissing, plug the opened ends with your finger to see if there is in fact suction coming from that tube or nozzle. You may notice a change in idle when the leak has been plugged or stopped. Good luck! Lee37726, my way of checking for leaks is to take a can of starting fluid (ether) and spray all the smaller lines, then wait 4 second for the engines reaction, then move to the next, not alot of spraying, just a fine mist for about a 2 seconds per half a foot of line, or depending on crevice of which spraying, your engine will always have a change in RPM if you have a Vacuum leak using this method, plus its cleaner and more reliable then the old take them off and check for hissing routine, but there ya go