Petrol Engine Cylinder Compression Leak-Down Tester Kit

This is a cylinder leak down tester used to diagnose the exact source and severity of compression loss in gasoline engines by pressurizing each cylinder (with piston at TDC) and measuring how much air escapes (leakage percentage). It reveals whether the leak is past the rings (piston/cylinder wear), valves (burnt/seated poorly), head gasket (into coolant/oil passages) or other areas—something a standard compression tester cannot do. While compression testing shows overall pressure (dynamic, cranking), leak down testing is static, more precise (percentage-based), and pinpoints the failure point. Professionals prefer it for engine rebuild decisions, tuning and troubleshooting misfires/rough running.

No, this kit is designed specifically for gasoline/petrol engines. Diesel engines operate at much higher compression ratios (often 15:1–22:1 vs. 8:1–12:1 for petrol) and require significantly higher test pressures (typically 300–500 psi or more) to simulate combustion conditions accurately. Using this 0-100 psi petrol-rated tester on a diesel can give misleading results or fail to detect issues. For diesel leak down testing, you need a dedicated high-pressure diesel-specific kit with appropriate adapters and gauges rated for diesel compression levels.

Yes, a compressed air source is required—typically a shop air compressor delivering at least 90–100 psi regulated pressure. The kit includes a 1/4" standard air quick plug and regulator valve to connect directly to your compressor and fine-tune input pressure. A small portable 12V compressor may work for light testing but often lacks sufficient volume/flow for consistent readings. Household compressors (2–6 hp) are ideal. Without steady regulated air supply, accurate leakage percentage measurement is not possible—do not attempt to use without proper air input.

It is usable by beginners with mechanical aptitude, but requires careful procedure and basic engine knowledge. You must bring each cylinder to exact TDC (top dead center) on the compression stroke, disable ignition/fuel, remove spark plugs, and follow the manual step-by-step to avoid false readings or damage. The dual gauges and clear percentage scale make interpretation straightforward (e.g., <10% good, 20–40% moderate wear, >60% major issue), but mislocating TDC or improper sealing can skew results. Watch detailed video tutorials first, work on a cool engine, and use eye/ear protection. For first-time users, professional guidance is recommended to ensure accurate diagnosis.