when my truck reaches running temp. a vacum leak starts it is comming from a vacum tube I have replaced this tube and the leak still happens when it warms up what do I do I have replaced all the hoses and vacum hoses help please
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2001 Ford Ranger Question: vacum leak
Answer #1patrick mannion from Greg Solow's Engine Room, August 21, 2009, 14:48Master
It shouldn't be necessary to replace all the hoses just the ones that are perished or damaged. Many automotive repair shops have a machine that generates an inert non flammable low pressure smoke that looks similar to cigar smoke. The intake manifold is sealed off, and smoke is put into the engines intake manifold. The smoke then fills the engines crankcase and if there are any vacuum leaks from gaskets, hoses, or housing smoke emits from the source of the leak. Some mechanics will use propane or aerosol carburetor cleaner, with the engine running they will spray the cleaner or propane around the intake manifold and vacuum hoses. A leak will cause a "lean mixture" condition, when the flammable fuel (carburetor cleaner or propane) comes in contact with the source of the vacuum leak the engine idle speed will raise as the engine has received "fuel". this method of finding a vacuum leak works but is not recommended as it can easily cause a fire.