Gnhydxfe Engine Cylinder Leak Down Tester Kit TU-21 Black — Dual-Gauge Manifold & Regulator

The Gnhydxfe TU-21 Engine Cylinder Leak Down Tester Kit is a dual-gauge diagnostic tool that lets you pressurize a cylinder to measure leakage paths and estimate internal engine wear quickly and accurately.

If you service cars, trucks or motorcycles and need a straightforward way to check piston rings, valves, head gaskets or cracked cylinder walls, this TU-21 kit connects to a shop air source and shows both applied pressure and the percentage of leakage at once. The kit bundles a dual-gauge manifold, hoses, multiple adapters and threaded/quick-connect fittings so you can access spark plug wells on most gasoline engines. Read on for how it works, what it includes, and when to reach for this tester.

How does the TU-21 reveal where an engine is leaking?

The tool pressurizes an individual cylinder through the spark plug hole and measures the pressure drop and leak rate simultaneously, making it easy to infer leak locations by listening or watching for pressure loss. Because you see both PSI and percent leakage, you can compare cylinders and pinpoint suspect areas for further inspection.

• Dual gauge reads 0–100 psi and 0–100% leakage for quick diagnostics.
• Pressurizes via spark plug well using supplied adapters and hoses.
• Listen for air escaping at intake, exhaust, crankcase or coolant passages to locate faults.
• Use pressure regulator to hold a steady test pressure from your air compressor.

What parts are included and what fittings make it versatile?

The TU-21 kit ships with a manifold assembly, an 18" hose, a pressure regulator valve, two gauges, and a selection of adapters so you can reach most gasoline engine spark plug holes. It also includes straight and angled push-on connectors for convenience where threading a fitting is difficult.

• Double gauge manifold with AR2000-style pressure regulator and American air plug.
• One rubber hose plus an extension hose and an M14 aluminum extension rod for deep wells.
• Two threaded adapters and two universal push-on connectors for wide engine compatibility.
• Adapters cover spark plug wells up to 20 mm and work on bikes, cars, and light trucks.

How do you use it safely and accurately in the shop?

Always follow basic safety: work on a cool engine, remove ignition and fuel sources, and rotate the engine to place the tested piston at near-TDC for a consistent baseline. Connect the manifold, set the compressor pressure with the regulator, pressurize the cylinder, then monitor leak percentage and listen for escaping air to determine the leak route.

• Ensure engine is off, cool, and ignition/fuel disabled before testing.
• Rotate piston to near-top-dead-center to isolate the tested cylinder.
• Adjust regulator to recommended test pressure and lock the valve knob for stable readings.
• Compare readings across cylinders to spot abnormal leakage percentages.

What accuracy and engine types is the TU-21 best suited for?

The gauges read 0–100 psi and 0–100% with stated accuracy near 0.5%, making the kit useful for routine shop checks and pre-purchase inspections on gasoline engines that accept spark plug style access. It's designed for petrol engines where spark plugs provide the test port and works with most passenger cars, light trucks and motorcycles.

• Pressure range: 0–100 psi (0–7 bar); leakage displayed 0–100%.
• Accuracy around 0.5% for comparative diagnostics across cylinders.
• Suitable for gasoline engines with spark plugs and wells up to 20 mm.
• Not intended as a precision laboratory instrument but ideal for workshop troubleshooting.

Who is this for: The Gnhydxfe TU-21 kit is aimed at home mechanics, mobile technicians and professional shops that need a rugged, flexible leak-down tester for routine engine assessments. If you perform cylinder-by-cylinder diagnostics, pre-purchase inspections, or maintenance on petrol engines, this kit supplies the gauges, adapters and hoses to locate common internal leaks quickly and without specialized tooling.