Michael Pardee wrote:
>>Anyone know what the best way is to find out where the vacuum leak is?
> Since most vacuum leaks come from cracks in the rubber vacuum hose where it
> attaches to nipples in various places (okay, guys, wipe those weird images
> out of your minds!) you can take any of the common approaches:
> *buy a bunch of vacuum hose in all the sizes you see under the hood and
> spend an hour or so replacing them all. The cost is reasonable and the
> benefits are lasting.
> *feel near the end of each hose for cracks and replace or trim the cracked
> end from the bad one(s). Repeat next time there is a vacuum leak.
> *if you can hear a whistle, try to isolate it. It isn't easy, but combined
> with the change in pitch if you get your finger on a crack it may pan out.
> Repeat next time....
> *buy a vacuum pump/guage combo - about $30 US IIRC - and see which hoses
> that come off the intake manifold hold vacuum. It is also possible to do it
> with the suck to draw a vacuum and place your tongue over the end to see if
> it holds, but that is really the po' boy's method and can get you an odd
> reputation. Repeat next time....
I had a leaky vacuum-advance diaphragm on my Accord's distributor that I
didn't know about because it wasn't audible like a leaky hose tends to
be.... I found it by pinching off the vacuum hoses (gently, with
non-serrated pliers) one at a time until pinching one caused a
noticeable change to the engine sound, speeding up a bit and smoothing
out. Start where the hoses come off the carb, throttle body, and/or
intake manifold with this one, and if you find one that has an effect,
you can move outward from there.
That's a unique method. It's far superior to the method that I learned. We
learned to remove each vacuum line and pinching off one end while we
it as hard as we could. They now have a device called a "vacuum/pressure
tester" that makes it easier. However, you method would work in some