Functional overview
The Mityvac digital compression test kit can
perform wet and/or dry compression tests to
determine the pressure produced in the
cylinders of a gasoline engine. It can meas-
ure, display, and store compression values of
up to psi (20 bar) (2,000 kPa) for up to
cylinders. It can also be used as a tool for
pressurizing an engine cylinder to hold the
valves closed while performing repairs.
When using this tester to perform a
compression test on a cylinder, the current
peak compression value is displayed in large
numbers at the center of the LCD. This value
is automatically transferred to memory, and
displayed in smaller numbers at the bottom
right of the display. When the pressure relief
button is depressed, the current compres-
sion reading returns to zero, but the peak
value is retained in memory and continues
to be displayed in the bottom right corner of
the LCD. Repeated tests can be run on the
same cylinder, and the new current peak
value will be displayed by the large numbers.
This new peak value will not be retained in
memory unless it surpasses the value of the
previous test, or the CLEAR button was
pressed to erase the old value from memory.
Peak compression values can be stored for
up to cylinders. Each is displayed on the
LCD along with the cylinder number. During
and/or after completion of testing all cylin-
ders, the peak values can be reviewed by
pressing the CYLINDER button to scroll
through the memory. Individual peak values
can be erased from memory by pressing the
CLEAR button when the appropriate cylinder
and value are displayed. Pressing the CLEAR
button for seconds at any time will clear
the memory for all cylinders and return the
display to cylinder .
How to perform a
comression test
Precautions and diagnostic
notes:
WARNING
Do not use the ignition switch during
the compression test on fuel-injected
vehicles. Use of a remote starter switch
to crank the engine is recommended.
Fuel injectors on many late model
vehicles are triggered by the ignition
switch during the cranking mode, this
could result in a fire hazard or contami-
nation of the engine’s oil with fuel.
An engine in good operating condition will
produce a certain amount of pressure in
each cylinder. Normally, the cylinders should
be within percentage points of one
another and within the manufacturer’s spec-
ifications. The pressure should rise smoothly
on each stroke of the engine, until it reaches
a peak.
If the pressure reading fails to rise, or it
remains the same for several strokes of the
engine and begins to rise, the likely cause of
the problem is a sticking valve.
If two adjacent cylinders show pressure
readings of or more pounds below the
other cylinder readings, suspect a blown
head gasket.
If a cylinder shows a pressure reading of
psi (1 bar) (100 kPa) or more pounds
higher than the other cylinders, the probable
cause is carbon build-up inside the cylinder.
The Mityvac digital compression test kit
can perform two tests: the dry compression
test and the wet compression test. The result
of performing these tests will provide an
indication of the condition of the piston rings,
cylinders, and valve-train.
Contact MityVac
If you have questions, or require technical
service, please contact our trained service
technicians at:--- ext.
Monday - Friday : am to : pm
CST
Visit our website at www.mityvac.com for
new products, catalogs and instructions for
product use.
To order replacement or service parts,
visit us online at www.mityvacparts.com or
call toll free ---.
Specifications
Maximum pressure : psi ( Bar)
(, kPa)
Included in this kit
• Digital Compression Tester comprising of
test gauge with rubber boot,
in (254 mm) long, high pressure hose,
and internal quick release coupler.
• () - Extended hose compression test
adapters:
– mm standard reach thread x
. in (165 mm) long
– mm standard reach thread x
in (305 mm) long
– mm long reach thread x
in (305 mm) long
– mm standard reach thread x
in (305 mm) long
• () - Plug style compression test adapters:
– mm long reach external thread x
mm standard reach internal thread
– mm external thread for Ford Triton
engines x mm standard reach inter-
nal thread
– mm external thread x mm stand-
ard reach internal thread
– mm external thread x mm stand-
ard reach internal thread
• Air hold adapter
• Custom blow-molded case
• Field service kit
