Date:         Thu, 14 Aug 1997 12:14:03 -0500 (CDT)
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         cmoran@cswnet.com (Colin A Moran)
Subject:      vacumn guage installation

.  Tim>Q: how does the vac gauge work?  long vac. tube to dash unit, or sensor
>with electric connection?  thanks.  Tim

Erik>I haven't read the earlier parts of this thread, but this is very
>interesting.  Do you mean you have a vacuum gauge hooked up so you see
>it as you are driving, on the dash?  If so, how have you hooked this up?
 >I have a 79 bus and would really like to hook up something similar.


Hello Tim, Erik
     I have installed a console above the windshield, the bottom of which is
just above the rear view mirror.  It extends across the van from door frame
to door frame.  I had to remove the sun visors to mount it.  I am thinking
about a mounting location just below the radio.  I question the wisdom of
removing the sun visors.  The hook up of the vacumn gauge is fairly easy.  I
used a mechanical vacumn guage. cheaper than an electric guage, also
electric guages are hard to find.  I used a small diameter vacumn hose to
connect the guage to the engine.  Remember that a vacumn hose has heavier
walls than a normal rubber hose.  This is to prevent the hose collapse and
the small size  improves accuracy over the long distance from the engine to
the dash.  I cut the vacumn line going into the fuel pressure regulator and
installed a tee.  I hooked the guage into the tee.  This may slow the
reaction of the fuel regulator, but I have had no problems with fuel
pressure.  The guage has been installed for about 5 years.  The guage
responds rapidly to engine vacumn changes despite long run.  

     At idle the engine pulls a vacumn of around 14" of Hg, or inches of
mecury.  Running at 65mph on level ground with a fresh tune-up the engine
pulls 10"of Hg.  Under heavy load, accelerating hard or pulling a steep hill
the vacumn will read about 2" to 4" of Hg.  when decelerating the reading
jumps to around 21" of Hg  The needle should at all times be steady or
smoothly changing. Any erratic movements of the needle indicate a possible
problem.  A stuck valve shows up as a reduced vacumn reading at idle with a
fluttering needle.  A vacumn leak shows up as a reduced reading at idle and
when decelerating.  When a reduced vacumn is noted at normal loads, cruising
or low speeds, its time for a tune-up.

     As with all diagnositc equipment it takes practice to be able to
determine a problem from the readings.  Take note of how the gauge reads and
then do a tune up.  This will aid you in determining how the engine reacts.
Also constant monitoring of the vacumn will teach you how your engine runs
normaly.  When you start seeing abnormal readings its time to check the
engine closer.

     If anyone has anymore questions I will try and answer them.
Colin Moran
'86 Syncro GL
"The Bronze Brick"
188,000 and still going