DAYUAN Petrol Engine Compression Tester Kit — Blue Case, 3" Dual-Scale Gauge & Adapters

DAYUAN Professional Petrol Engine Compression Tester Kit is a complete diagnostic set that measures cylinder compression across a wide range of petrol engines using a 3" dual-scale gauge and multiple adapters in a durable blue case.

This compression tester kit gives mechanics and DIYers the tools to check engine health quickly and accurately. The set includes a 3" gauge with dual color markings (0–300 psi / 0–20 bar), four threaded fittings with O-rings, two spark plug adapters, and two rubber cone ends for non-threaded checks — all organized in a protective blue storage case. It’s designed to fit many modern and older petrol engines so you can diagnose worn rings, leaking valves, or head gasket issues without guesswork.

How do I use the DAYUAN tester to check cylinder compression?

Start by removing the spark plug from the cylinder you want to test, then screw in the appropriate adapter or seat a rubber cone for quick checks. Crank the engine several revolutions with the throttle open while watching the gauge; the highest steady reading is the cylinder’s compression. Compare readings across cylinders to identify discrepancies that indicate mechanical problems.

• Choose correct adapter: M10, M12, M14, M18 or 14mm/18mm spark plug fittings
• Use rubber cones for quick, non-threaded checks
• Record peak pressure after 4–6 cranks for accuracy
• Open throttle fully to allow maximum cylinder airflow

Which engines and plugs will this kit fit?

The kit covers a broad range of petrol engines thanks to its threaded fittings and spark plug adapters. It works with standard spark plug ports and many specialized plug types because of the included male-threaded fittings with O-rings and two common spark plug adapters. For unsupported or unusual ports, the rubber cone ends provide a non-invasive alternative to get a quick pressure estimate.

• Threaded fittings: M10, M12, M14, M18 (male with O-ring)
• Spark plug adapters: 14mm and 18mm included
• Rubber cone ends for non-threaded or deep plug holes
• Suitable for most petrol automotive and small engine cylinders

What does the 3" dual-scale gauge tell me and why it matters?

The 3-inch gauge displays pressure in both psi (0–300) and bar (0–20) using an easy-reading dual-color scale, so you can read diagnostics in your preferred unit. A clear, large face reduces parallax error and helps you spot peak and resting pressures quickly. Consistent readings let you compare cylinders and determine the severity of compression loss.

• Range: 0–300 psi and 0–20 bar on a single dial
• Large 3" face improves visibility under shop lighting
• Dual-color scale simplifies quick interpretation
• Use peak reading after steady revolutions for reliable results

What accessories are included and how do they improve testing?

The kit bundles adapters, cones, and fittings so you can test a wide variety of petrol engines without hunting for parts. O-ring sealed male fittings prevent leakage at the connection point, while spark plug adapters let you thread directly into plug holes for accurate readings. The two rubber cone ends enable fast checks when threading is impractical or time is limited.

• Four male threaded fittings (M10, M12, M14, M18) with O-rings for tight seals
• 14mm and 18mm spark plug adapters for common plug sizes
• Two rubber cone ends for quick checks without threading
• Durable blue storage case keeps components organized and protected

Who this is for: the DAYUAN Petrol Engine Compression Tester Kit is ideal for professional mechanics, automotive technicians, and informed DIYers who perform routine engine diagnostics and repairs. If you need a portable, adaptable tool that delivers clear pressure readings across many petrol engines, this kit supplies the fittings and gauge to get repeatable results without extra purchases.