One more way to find a vacuum leak

[79glide]

I replaced the easy to get to hoses, sprayed various liquids on the complete intake, and tried propane to find a vacuum leak on my M44. I spent a lot of time and did not make much of an improvement. I was getting to the point where I needed a pro with a smoke machine to find the leak when I got one more idea. I bought a 3" plumbing pipe expandable test plug at home depot to put in the air intake. Then I put together a small air regulator and some pipe fittings to supply a very low pressure air supply to the intake system. I was concern the engine crank might need to be rotated to a certain position to keep the intake pressurized. To my surprise I found the leak in 30 seconds after applying the air pressure! The crankcase vent valve was leaking! It made a big difference once it was replaced. I verified all the leaks were fixed with a manifold vacuum gauge. Keep in mind the computer will try to compensate for small vacuum leaks.

[Jean H.318TI]

yeah same way u look for boost leaks on turbo cars

[airborneSGT]

I have to see a picture of diagram of this device. If you have time would be great to see some pictures.