Vacuum Leak Diagnosis and Repair. [Inquiry]Anyone know of a good method of test for and locating vacuum leaks in the the air intake system?
• By Listening. [Response: Don Foster] Find or buy a 3′ length of new fuel hose. Stick one end in your ear and snoop around the intake system with the other end listen for any pronounced hisssssssing. [Warren Bain] I was able to isolate a vacuum leak with a mechanic’s stethoscope with the probe removed and only using the tubing to get very close to the gasket and follow the contour of the manifold. You can also modify the stethoscope for locating vacuum leaks by replacing the probe with a length of plastic hose or fuel line. • Spraying With Liquid. Another trick, for small leaks such as loose intake manifolds or shrunken injector seals, is to spray them with carb cleaner. This will temporarily seal a leak and a rough idle will smooth out for 10-15 seconds: you will hear the change in idle rpm. • Using Propane to Alter the Mixture. [Tip from Bruce Young] I use Propane to test for vacuum leaks It’s as safe (or safer) and less messy than spraying carb cleaner or other flammables . Take th
