sucky vacuum question

[Randy G.]

So I have been going through my 240 looking for any and all problems
and taking care of them as I go. With my Mityvac (hand vacuum/pressure
pump with gauge) I have been checking various hoses and systems on the
car. It intrigued me that the line that goes from the manifold to the
interior of the car that supplies vacuum to the ventilation system
(operates through the defrost/recirculation buttons) to operate the
various vacuum motors under the dash does not hold vacuum at all.
Another 240 owner stated much the same thing. Now, do we have a
problem, or is that the way they are supposed to operate? It seems odd
that a vehicle that is so sensitive to manifold vacuum levels would
'leak' that much vacuum anywhere.

__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

 

[James Sweet]

So I have been going through my 240 looking for any and all problems
and taking care of them as I go. With my Mityvac (hand vacuum/pressure
pump with gauge) I have been checking various hoses and systems on the
car. It intrigued me that the line that goes from the manifold to the
interior of the car that supplies vacuum to the ventilation system
(operates through the defrost/recirculation buttons) to operate the
various vacuum motors under the dash does not hold vacuum at all.
Another 240 owner stated much the same thing. Now, do we have a
problem, or is that the way they are supposed to operate? It seems odd
that a vehicle that is so sensitive to manifold vacuum levels would
'leak' that much vacuum anywhere.

I've seen the vacuum resivoir behind the heater box split at a seam before,
there's also a tangle of vac hoses behind the center console, one of them
may have split or popped off. It should hold a vacuum well, though there's a
fair amount of air to evacuate and if any of the buttons are pushed a vac
solenoid will suck in so you may have to pump for a while but it should
hold.

 

[Randy G.]

I've seen the vacuum resivoir behind the heater box split at a seam before,
there's also a tangle of vac hoses behind the center console, one of them
may have split or popped off. It should hold a vacuum well, though there's a
fair amount of air to evacuate and if any of the buttons are pushed a vac
solenoid will suck in so you may have to pump for a while but it should
hold.

Thanks, James. I was hoping that you would respond. Just knowing that
the system _SHOULD_ hold a vacuum is a great starting place for me.

I did try 'pumping' the system quickly with the Mityvac but it rapidly
returned to "0" vacuum. Looks like it is time to lay on the floor
again. The Mityvac should make it an easy matter to isolate the
problem. The various vacuum motors are operating as I can get defrost
and recirculation changes... we shall see...





__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

 

[Mike F]

Thanks, James. I was hoping that you would respond. Just knowing that
the system _SHOULD_ hold a vacuum is a great starting place for me.

I did try 'pumping' the system quickly with the Mityvac but it rapidly
returned to "0" vacuum. Looks like it is time to lay on the floor
again. The Mityvac should make it an easy matter to isolate the
problem. The various vacuum motors are operating as I can get defrost
and recirculation changes... we shall see...

__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

You can try to isolate the problem by moving the vacuum switches, which
will switch the "motors" out of the system, depending on switch
position. If the problem goes away with a switch in a certain position,
then you've narrowed the problem down to that leg of the system. If the
problem stays for all switch positions, then the problem is in the
vacuum supply side of the system.

--
Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)