Product Specifications

• Compression pressure testing in gasoline engines
• Includes 5 spark plug adapters
• Angled aluminum test bar for V-shape engines
• Gauge reading: 0-300 psi
• M16 spark plug adapter for Ford F-150 and Triton

Preparation Steps

• Engine Start: Start the engine for approximately 10 minutes or until the engine reaches normal operating temperature. Turn off the engine.
• Disconnecting Spark Plugs: Disconnect the spark plug wire from the first cylinder and mark the cylinder number on the wire. Remove the spark plug and place it on a clean surface. Check the spark plug condition. Replace if necessary and clean the spark plug hole.
• Check Spark Plug Condition: Note: The condition of the spark plug can also indicate the condition of the cylinder and compression pressure.
• Disconnecting the Central High Tension (HT) Lead: Disconnect the central HT lead from the distributor and ground it. For electronic ignition systems, remove the electronic ignition device or ignition coil. For GM high-energy ignition (HEI) systems, disconnect the main wire from the distributor cap.

Compression Pressure Test

• Method A: Choose a suitable adapter and connect it to the rubber test hose. Screw the adapter and rubber test hose onto the spark plug hole.
• Method B: Choose a suitable aluminum test tube. Install the aluminum test tube on the spark plug hole. Note: When using the aluminum test tube (angled or straight), one hand must hold and press the test tube against the spark plug hole at all times.
• Connect the gauge to the rubber test hose or aluminum tube.
• Start the engine to run at least 4 compression strokes or until the pressure gauge reading stabilizes at a fixed level.
• Record the pressure reading.
• Press the pressure release button before disconnecting from the cylinder.
• Reinstall the spark plug and wire back to the cylinder.
• Test other cylinders one by one and compare the test results.

Test Results

• The pressure should rise after each compression stroke and then reach a maximum under normal conditions.
• The pressure of each cylinder in the same engine should follow the standards set by the auto manufacturer.
• If the pressure does not rise after several compression strokes, the valves could be clogged.
• The highest pressure and the lowest pressure should not exceed 20 psi or 15% difference.
• If the pressure is much higher than the standard set by the manufacturer, there could be carbon deposits.
• If the pressure in one cylinder is significantly lower than other cylinders, put a teaspoon of SAE30 engine oil into the cylinder.
• If the pressure increases significantly, the piston rings could be worn out or the cylinder head is not properly installed.
• If the pressure remains the same, the valves could be worn out or need adjustment.