U.S. General 94190 User manual

Cylinder Leakage Tester
ASSEMBLY AND OPERATING INSTRUCTIONS
94190
®
3491 Mission Oaks Blvd., Camarillo, CA 93011
Visit ourWeb site at http://www.harborfreight.com
Copyright © 2006 by Harbor Freight Tools®. All rights reserved. No portion of this
manual or any artwork contained herein may be reproduced in any shape or form
without the express written consent of Harbor Freight Tools.
For technical questions and replacement parts, please call 1-800-444-3353
Due to continuing improvements, actual product may differ slightly from the product described herein.

Page 2SKU 94190 For technical questions, please call 1-800-444-3353.
Specifications
Save This Manual
You will need the manual for the safety warnings and precautions, assembly
instructions, operating and maintenance procedures, parts list and diagram. Keep
your invoice with this manual. Write the invoice number on the inside of the front
cover. Keep the manual and invoice in a safe and dry place for future reference.
Safety Warnings and Precautions
WARNING: When using tool, basic safety precautions should always be fol-
lowed to reduce the risk of personal injury and damage to equipment.
Read all instructions before using this tool!
1. Keep work area clean. Cluttered areas invite injuries.
2. Observe work area conditions. Do not use machines or power tools in
damp or wet locations. Don’t expose to rain. Keep work area well lighted.
Do not use electrically powered tools in the presence of flammable gases or
liquids. Be aware of the inherently dangers of working on a gasoline engine.
3. Keep children away. Children must never be allowed in the work area. Do
not let them handle machines, tools, or extension cords.
4. Store idle equipment. When not in use, tools must be stored in a dry
location to inhibit rust. Always lock up tools and keep out of reach of children.
5. Use the right tool for the job. This cylinder leakage tester is intended for
use in gasoline powered engines. Do not modify this tool and do not use this
tool for a purpose for which it was not intended.
6. Dress properly. Do not wear loose clothing or jewelry as they can be caught
in moving parts. Protective, electrically nonconductive clothes and nonskid
footwear are recommended when working. Wear restrictive hair covering to
contain long hair.
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Page 3SKU 94190 For technical questions, please call 1-800-444-3353.
7. Use eye and ear protection. Always wear ANSI-approved impact safety
goggles when working on gasoline engines. Be sure to work in a well
ventilated place, or pipe exhaust gasses to the outdoors. Carbon Monoxide
Warning: Guard against exposure to Carbon Monoxide, which is an odorless,
colorless gas produced by gasoline engines. Carbon Monoxide exposure may
cause serious injury or death.
8. Do not overreach. Keep proper footing and balance at all times. Do not
reach over or across running machines.
9. Maintain tools with care. Keep tester threads sharp and clean for better
and safer performance. Follow instructions for lubricating and changing
accessories.The gauge hose and adapters must be kept clean, dry, and free
from oil and grease at all times.
10. Stay alert. Watch what you are doing, use common sense. Do not operate
any tool when you are tired.
11. Check for damaged parts. Before using any tool, any part that appears
damaged should be carefully checked to determine that it will operate
properly and perform its intended function. Any part that is damaged should be
properly repaired or replaced by a qualified technician.
12. Replacement parts and accessories. When servicing, use only identical
replacement parts. Use of any other parts will void the warranty.
13. Do not operate tool if under the influence of alcohol or drugs. Read
warning labels on prescriptions to determine if your judgment or reflexes are
impaired while taking drugs. If there is any doubt, do not operate the tool.
14. Maintenance. For your safety, service and maintenance should be performed
regularly by a qualified technician.
WARNING: The brass components of this product contain lead, a chemical
known to the State of California to cause birth defects (or other reproductive
harm). (California Health & Safety code 25249.5, et seq. )
WARNING:The warnings, cautions, and instructions discussed in this instruc-
tion manual cannot cover all possible conditions and situations that may oc-
cur. It must be understood by the operator that common sense and caution
are factors which cannot be built into this product, but must be supplied by
the operator.

Page 4SKU 94190 For technical questions, please call 1-800-444-3353.
Unpacking
When unpacking, check to make sure the following parts are included.
Cylinder Leakage Tester with Quick Release Chuck
14mm and 18mm Adapters Adapter Hose Molded Plastic Case
If any parts are missing or broken, please call Harbor Freight Tools at the number
on the cover of this manual.
About Cylinder Leakage Testing
A Cylinder Leakage Tester can give you valuable information about the engine’s
compression. Pressurized air is supplied to each cylinder, and the rate of leakage
is measured in percent loss from 0% to 100%.
The operator may also locate the source of the compression loss by listening at
these places:
a) Oil dipstick tube for leaking cylinder rings.
b) Radiator fill cap for cylinder wall cracks.
c) Adjacent port for head gasket leaking.
d) Tailpipe for exhaust valve leaks.
e) Carburetor air horn for intake valve leakage.
f) Fuel injector body for intake valve leakage.
If you are not experienced in doing this type of diagnostic test, the work
should be done by a qualified technician.
Cylinder
Leakage
Tester with
Quick Release
Chuck
14mm and 18mm
Adapters
Adapter Hose
REV 03/07

Page 5SKU 94190 For technical questions, please call 1-800-444-3353.
Important Considerations About Compression Loss Testing
1. There will always be some compression loss past piston rings, even in a new
engine.You will never see a 0% compression loss, and this lost pressure
should be audible at the oil dipstick port.
2. If the Leakage Gauge shows very high or 100% compression loss, the cylinder
may not be at Top Dead Center (TDC) on the compression stroke. Check to
be sure the cylinder is at TDC, so the valves are closed. Reference your
vehicle owner’s manual for instructions on how to do this.
3. A “good” reading will show compression loss of all cylinders at about the same
rate. A large difference of 15% to 30% comparing one cylinder to the others
indicates a problem.
4. Leakage rate readings may vary by up to 10% when taking repeated readings
of the same cylinder. Piston position and engine temperature can cause
variable readings.Take several readings and average the results for a recorded
reading for each cylinder.
5. Diagnosing an engine problem with this tool involves using a listening device
(not included). A length of hose or a mechanic’s stethoscope are suggested.
6. The lower the sound pitch of escaping pressure indicates a larger leak. Small
leaks will typically make a higher pitched sound.
7. If the vehicle has multiple problems, the Cylinder Leakage Tester may show
only the most pronounced problems. A large problem may overwhelm a
smaller problem during testing.
Operation
IMPORTANT NOTE: Be sure the Regulator Knob (9) is turned fully counter-
clockwise before connecting the Cylinder Leakage Tester to a pressurized
air source. Failure to do so may result in damage to the tool.
NOTE: The engine must be at normal operating temperature for accurate testing.
Start the engine and let it warm up to normal operating temperature, then turn it off
for testing.
CAUTION: Always run an engine in a well ventilated space. Running en-
gines produce Carbon Monoxide, a colorless, odorless gas which can cause
serious personal injury or death if inhaled.

Page 6SKU 94190 For technical questions, please call 1-800-444-3353.
WARNING: Wear protective gloves and ANSI-approved eye protection when
working on a hot engine. Keep hands away from the fan and other moving parts,
and protect yourself from electrical shock or burns. Be aware that working on a
gasoline engine is inherently dangerous, and suitable precautions must be taken.
1. Before removing the spark plugs, clean the area around the spark plugs using
compressed air. It is important to prevent foreign materials from falling into the
cylinders once the spark plugs are removed.
2. Disconnect the coil wire from the coil, and remove all spark plugs. Note the
position of the wires so that the correct wire may be replaced on each plug at
the end of the job. On engines with two spark plugs per cylinder, remove only
one plug per cylinder.
3. Remove the oil dipstick, radiator cap, and disconnect one end of the PCV
hose.If the engine has a carburetor, remove the air cleaner and open the
throttle all the way. If the engine is fuel injected, remove the air cleaner or open
the throttle body.
4. Position the cylinder to be tested at TDC on the compression stroke so all
valves are closed.
5. Turn the Regulator Knob fully counterclockwise. Connect the Cylinder Leakage
Tester to a compressed air source (not included). NOTE: Be sure the air
compressor’s regulator is set from 7 to 100 PSI. Never operate this tester
with air pressure set higher than 100 PSI, which can damage this tool.
6. Hand screw the Adapter Hose (10) into the spark plug hole of the cylinder to
be tested. Connect the male end of the adapter Hose to the female coupler of
the extension hose.
7. Turn the Regulator Knob (9) clockwise until the Leakage Gauge (6) reads “0”
(zero) at the end of the yellow band.
8. You can now read the amount of leakage on the Leakage Gauge (6) as a
percentage loss.
9. Test the remaining cylinders to determine which if any cylinders are bad.
10. Use the diagnostic techniques in the next section to determine the cause of
the problem.
REV 09/06

Page 7SKU 94190 For technical questions, please call 1-800-444-3353.
Diagnostic Techniques
If one or more cylinders are identified as having 15% to 30% greater compression
loss than the others, you can listen for escaping air pressure to diagnose the
problem. Air escaping at the following locations indicates a potential problem.
1. Oil dipstick tube indicates pressure escaping from the cylinder into the oil
jacket. This usually indicated stuck, burned or worn rings or cylinder walls.
2. Radiator filler opening bubbles or sound indicates pressure escaping into the
coolant jacket. This can indicate cracked cylinder walls or damaged head
gasket. In case of a damaged head gasket, often two or more adjacent
cylinders will show the same problem.
3. Adjacent cylinder indicates a damaged head gasket.
4. Tail pipe indicates burned, stuck or worn exhaust valve.
5. Carburetor or fuel injector intake indicates stuck, burned or worn intake valve.
Maintenance
Very little maintenance of this tool is required. Keep this tool clean and free from
dirt, grease or grit. Store it in its case when not in use. Periodically check the
threads for damage. Release the pressure from the gauge before storing.
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Page 8SKU 94190 For technical questions, please call 1-800-444-3353.
PLEASE READ THE FOLLOWING CAREFULLY
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS DIAGRAM
IN THIS MANUAL AS A REFERENCE TOOL ONLY. NEITHER THE MANUFACTURER
NOR DISTRIBUTOR MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND TO
THE BUYERTHAT HE OR SHE IS QUALIFIEDTO MAKE ANY REPAIRSTOTHE PRODUCT
OR THAT HE OR SHE IS QUALIFIED TO REPLACE ANY PARTS OF THE PRODUCT. IN
FACT, THE MANUFACTURER AND/OR DISTRIBUTOR EXPRESSLY STATES THAT ALL
REPAIRS AND PARTS REPLACEMENTS SHOULD BE UNDERTAKEN BY CERTIFIED
AND LICENSED TECHNICIANS AND NOT BY THE BUYER.THE BUYER ASSUMES ALL
RISK AND LIABILITY ARISING OUT OF HIS OR HER REPAIRS TO THE ORIGINAL
PRODUCT OR REPLACEMENT PARTS THERETO, OR ARISING OUT OF HIS OR HER
INSTALLATION OF REPLACEMENT PARTS THERETO.
LIMITED 90 DAY
WARRANTY
Harbor FreightTools Co. makes every effort to assure that its products meet high quality and durability standards,
and warrants to the original purchaser that this product is free from defects in materials and workmanship for
the period of 90 days from the date of purchase. This warranty does not apply to damage due directly or
indirectly, to misuse, abuse, negligence or accidents, repairs or alterations outside our facilities, or to lack of
maintenance.We shall in no event be liable for death, injuries to persons or property, or for incidental, contingent,
special or consequential damages arising from the use of our product. Some states do not allow the exclusion
or limitation of incidental or consequential damages, so the above limitation of exclusion may not apply to
you.THIS WARRANTY IS EXPRESSLY IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS.
To take advantage of this warranty, the product or part must be returned to us with transportation charges
prepaid. Proof of purchase date and an explanation of the complaint must accompany the merchandise. If our
inspection verifies the defect, we will either repair or replace the product at our election or we may elect to
refund the purchase price if we cannot readily and quickly provide you with a replacement. We will return
repaired products at our expense, but if we determine there is no defect, or that the defect resulted from
causes not within the scope of our warranty, then you must bear the cost of returning the product.
This warranty gives you specific legal rights and you may also have other rights which vary from state to state.
3491 Mission Oaks Blvd. • PO Box 6009 • Camarillo, CA 93011 • (800) 444-33533491 Mission Oaks Blvd. • PO Box 6009 • Camarillo, CA 93011 • [phone]
3491 Mission Oaks Blvd. • PO Box 6009 • Camarillo, CA 93011 • (800) 444-33533491 Mission Oaks Blvd. • PO Box 6009 • Camarillo, CA 93011 • [phone]
3491 Mission Oaks Blvd. • PO Box 6009 • Camarillo, CA 93011 • [phone]
®
WARRANTY