<VV> RE: Vacuum valve modulator leak check

[Craig Nicol]

<snip> The manual on p. 7-34 it states, "The vacuum modulator can be checked
with a vacuum source for leakage.  However, leakage normally results in
transmission oil pull-over and results in oil smokey exhaust and continually
low transmission oil.  No vacuum modulator repairs are possible; replace as
an assembly unit."  I am not experiencing smoky exhaust, and the only
transmission fluid loss that I'm experiencing is a faultily installed
gasket (my learning experience) which has slow leaks on two of the bolts.
Stephen <Unsnip>

There are two kinds of leaks possible in the vacuum modulator circuit, an
air leak and a fluid leak (internal vacuum modulator failure).  The leak
described in the text above is a fluid leak inside the vacuum modulator.
This type of leak causes ATF to be sucked into the engine and burned to
create smoke.

Disconnect the rubber line between the vacuum balance tube and the steel
modulator line in the engine compartment.  Use your MityVac to suck on the
modulator line.  Observe the MityVac gauge to confirm that the modulator and
lines hold vacuum.

If they don't hold vacuum, repair the leak or replace the modulator.  (A
leaking modulator usually shows ATF in the nipple and hose.)

If the system holds vacuum, inspect the balance tube for leaks.  Just for
grins, check the idle vacuum of the engine overall. (Remove one choke
pull-off hose and check vacuum @ hose using vacuum gauge.  It should be 14",
give or take, at idle.  Low vacuum can be caused by a large vacuum leak or
internal issues such as an incorrectly installed camshaft. 

Your car has A/C.  AFIR, that set-up requires a separate PCV valve. A
defective, missing, or incorrectly installed PCV can cause low vacuum.  Is
it there, installed correctly, and in good condition?  Also, AFIR, the
idle-up solenoid is vacuum operated on a '65.  Use your MityVac to check for
a vacuum leak in that circuit starting with its connection to the balance
tube. 

Hope that helps!
Craig Nicol