Compression Tester for Petrol Engines Jonnesway AR020017

Jonnesway AR020017 is a compression tester designed for petrol (gasoline) engine cylinders. It provides a simple means to measure cylinder compression pressure, enabling diagnosis of engine health and identification of issues such as worn piston rings, leaking valves or head gasket failures. The tool is portable and suitable for both workshop and roadside diagnostics, offering mechanics and DIY enthusiasts a reliable way to verify compression values and compare performance between cylinders.

Advantages

The Jonnesway compression tester offers quick, direct measurement of cylinder pressure with a compact, handheld design that is easy to carry and store. Its connection fittings and pressure gauge are intended for repeated use in routine checks, allowing users to identify low-compression cylinders and diagnose related faults without disassembling the engine. The device is compatible with typical petrol engine spark plug threads and is useful for comparing readings across multiple cylinders to detect uneven wear or sealing problems.

Suitable for

• Inspection of petrol engine cylinder compression in passenger cars and light commercial vehicles
• Routine diagnostic checks in workshops and mobile service operations
• Pre-purchase vehicle inspections and troubleshooting of starting or power loss issues
• Hobbyist and DIY engine maintenance and comparative cylinder testing

Key specifications

• Designed for use with petrol (gasoline) engine cylinders
• Handheld, portable tester suitable for workshop and roadside use
• Mechanical pressure gauge for direct reading of compression values
• Fittings compatible with common spark plug thread sizes for petrol engines
• Durable construction intended for repeated diagnostic use

How to use

Perform testing with the engine off and the ignition disabled. Remove the spark plug from the cylinder to be tested, attach the tester fitting securely into the spark plug hole, and crank the engine several revolutions while observing the pressure gauge. Record the peak compression value and repeat the procedure for each cylinder, ensuring identical starting conditions such as throttle position and battery charge. Compare readings between cylinders and against manufacturer specifications to identify cylinders with abnormally low compression.

Usage recommendations

Take safety precautions: disable the ignition system to prevent accidental engine start and follow vehicle manufacturer guidance. Warm the engine to normal operating temperature before testing for more representative readings. If a cylinder shows low compression, perform a wet test by adding a small amount of oil into the cylinder to distinguish between worn rings and valve or head gasket leaks.