Cylinder Leakage Testers

About Cylinder Leakage Testers

Cylinder leakage testers are precision diagnostic instruments that enable automotive professionals to accurately assess engine condition by measuring the percentage of compressed air escaping from combustion chambers. Unlike basic compression testers that only measure pressure build-up, these sophisticated tools introduce regulated compressed air into each cylinder at top dead centre and quantify leakage, revealing critical information about piston ring wear, valve sealing, head gasket integrity, and cylinder head condition. MyToolShed.co.uk stocks professional-grade cylinder leakage testers from trusted manufacturers including Sealey and Draper, featuring dual-gauge systems that simultaneously display regulated input pressure and leakage percentage for accurate, repeatable diagnostics.

These comprehensive diagnostic kits typically include multiple spark plug thread adaptors (10mm, 12mm, 14mm, and 18mm) to accommodate various petrol engines across cars, motorcycles, and light commercial vehicles. The dual-gauge configuration allows technicians to maintain consistent test pressure—typically 100 PSI or 7 bar—whilst monitoring leakage readings. By listening carefully at the exhaust, intake, crankcase breather, or cooling system whilst the cylinder is pressurised, experienced mechanics can pinpoint specific failure points without invasive engine disassembly.

Applications

• Independent Garage Technicians – diagnosing engine performance issues, verifying repair quality, and conducting pre-purchase vehicle inspections
• Mobile Mechanics – performing on-site engine diagnostics and condition assessments at customer locations
• MOT Testing Stations – investigating emissions failures and underlying engine condition concerns
• Classic Car Restorers – assessing engine condition before rebuild decisions and post-restoration verification
• Motorcycle Mechanics – testing single and multi-cylinder engines in bikes, scooters, and off-road machines
• Racing Teams and Performance Tuners – monitoring engine condition and optimising seal performance for competition use
• Fleet Maintenance Departments – conducting preventative maintenance assessments on company vehicles

Choosing The Right Cylinder Leakage Testers

Gauge Quality: Select testers with large, clearly marked dual gauges displaying both regulated input pressure and leakage percentage. Professional instruments feature precision calibration and protective rubber surrounds for workshop durability.

Adaptor Selection: Ensure the kit includes adaptors for spark plug thread sizes you'll encounter frequently. UK workshops typically require 14mm and 18mm fittings, whilst motorcycle specialists need 10mm and 12mm adaptors. Comprehensive kits from MyToolShed.co.uk cover multiple applications.

Build Quality: Professional testers must withstand frequent use. Look for robust brass or steel fittings, reinforced hoses resistant to kinking, and quality construction from established brands like Sealey and Draper.

Pressure Regulation: The tester should maintain steady regulated pressure (typically 100 PSI or 7 bar) throughout testing. Built-in regulators with adjustment controls ensure consistent, comparable results across different engines.

Safety Information

Always wear appropriate eye protection when working with compressed air systems. Never exceed recommended test pressures, as excessive pressure can damage engine components or cause injury. Before testing, ensure the engine cannot rotate unexpectedly by placing the transmission in gear, applying the parking brake firmly, and securing the vehicle properly—pressurised air in the cylinder can cause violent rotation if not secured at top dead centre. Conduct testing in well-ventilated areas and allow engines to cool to safe working temperatures before removing spark plugs.

Frequently Asked Questions

What's the difference between compression and leakage testing?
Compression testers measure maximum pressure generated during the compression stroke, providing relative engine condition. Cylinder leakage testers introduce known pressure and measure escaping air as a quantifiable percentage, precisely identifying seal effectiveness and revealing where problems exist through careful listening whilst the cylinder is pressurised.

What leakage percentage indicates engine problems?
Generally, readings below 10% indicate excellent condition, 10-20% is acceptable for normal use, whilst readings above 20% suggest significant wear requiring attention. Context matters—race engines might require sub-5% leakage for optimal performance, whilst older utility vehicles with 25% leakage might provide adequate service depending on leakage source.

Do I need a special compressor for cylinder leakage testing?
You'll need a workshop compressor delivering clean, dry air at approximately 100 PSI (7 bar) with sufficient volume to maintain pressure during testing. Most professional workshop compressors meet these requirements. Ensure your air system includes moisture separation to prevent gauge damage and inaccurate readings.