You might try putting some soapy water or spit around the fitting where the
release button is, just below the gage to see if bubbles are present with
some pressure applied.
Then, if that release button assembly can be disassembled, you might find a
fleck of dirt or possibly a missing ball or spring.
In the section where the button is, there should probably be a check valve
which holds the pressure in the gage until the user presses the button.
There are also some types of compression testers which have the check/tire
valve core located at the end of the tube where the rubber tip is (which is
intended to seal in the spark plug hole.
But the release button on the Proto gage should engage something acting as a
check valve.
Another less likely fault could be that there is an internal leak in the
Proto gage, which is a little more complicated to check and repair, but
possible.
--
WB
..........
"Ken Grunke" wrote in message
...
The gauge on my old compression tester decided it had served well enough
after several years of non-use, it's demise helped along by a good dose of
rust. I needed one for a project car I just started working on so I went
ebay shopping for a replacement gauge to go on my hose & adapters.
I found a Proto CTR-20 gauge on ebay, USA made, brand new according to
seller, with a release valve for a good price of $15 including shipping but
there isn't a check valve to hold the pressure for cumulative readings. On
my old gauge, it must be built into the gauge's body as I don't see any kind
of external check valve on it.
When cranking the engine, the needle jumps up to max and back to zero for
each cycle. I'm not familiar with how a standard automotive compression
tester is supposed to work here, other than it should hold the pressure and
increase the reading a bit with each crank cycle of the motor.
Can anyone enlighten me on how to get this working the way I remember it
should?
Here's the gauge screwed onto my hose:
http://www.token.crwoodturner.com/im...iongauge01.jpg
http://www.token.crwoodturner.com/im...iongauge02.jpg