CYLINDER LEAK TESTER

Item No:MP73055
 

1. Core role: quantitatively detect cylinder tightness and locate internal component failures

The core principle of the tester is: after the spark plug is removed, compressed air at rated pressure (usually 80-100PSI) is charged into the cylinder through a special joint, and the tightness of the cylinder is judged based on the air pressure leakage rate. It is mainly used for testing:

 

Wear or break of piston rings: The seal between the piston ring and the cylinder wall fails, causing compressed air to leak.

Scratch or wear on the cylinder wall: Abnormal wear on the cylinder wall damages the sealing surface, causing a drop in air pressure.

 

Poor valve seals: The intake/exhaust valves are not tightly sealed to the valve seat rings, causing air to leak into the intake manifold or exhaust pipe.

Cylinder gasket damage: After the cylinder gasket breaks down, compressed air leaks into the water channel, oil passage or adjacent cylinder.

 

 

 

2. Specific use scenarios

(1) Engine power drop/abnormal sound diagnosis

Location of the root cause of insufficient cylinder pressure

If the engine power drops and acceleration is weak, the conventional cylinder pressure test can only determine the pressure value, while the leak test can further determine the leak location:

 

Leakage rate>20% and intake manifold leakage sound is heard: indicating poor intake valve sealing;

Leakage rate>30% and exhaust pipe leaks: indicating that the exhaust valve seal fails;

Leakage rate>40% and air bubbles emerge from the oil filler port: indicating that the piston ring is worn or the cylinder wall is scratched;

Bubbles emerge from the coolant expansion pot: Prompt that the cylinder pad has penetrated into the water channel.

 

Check for abnormal noise and abnormal wear

When the engine knocks the cylinder or burns oil, it is judged through the leak test:

Leakage caused by piston ring wear will be accompanied by "pulling cylinder" marks on the cylinder wall, and the leakage rate is usually>50%;

Poor valve sealing may be caused by stuck carbon deposits or worn valve seat rings, and the leakage rate is mostly 20%-30%.

 

(2) Performance verification before and after maintenance

Pre-overhaul fault assessment

Before engine overhaul, leak testing is used to quantify the damage degree of each cylinder to determine whether it is necessary to bore the cylinder, replace the piston ring, or grind the valve (if a cylinder has a leakage rate of 60%, key maintenance is required).

 

Seal verification after repair

After replacing piston rings, valves or cylinder gaskets, test again and ensure that the leakage rate should be less than 10%(normal cold condition) to ensure maintenance quality. For example, after grinding the valve, the leakage rate drops from 30% to 5%, indicating that the seal was successfully repaired.

 

(3) Multi-scenario application scenarios

Used car engine detection: judge whether the engine is "internal injury" through leakage test, avoid buying vehicles that burn oil or power attenuation (such as a cylinder leakage rate>30%, prompt overhaul).

 

Racing engine tuning: high performance engine requires leakage rate <5%, through testing to optimize piston ring tension, valve grinding accuracy, improve compression ratio and power output.

 

Engineering machinery engine maintenance: If the engine of excavator, loader and other equipment has abnormal leakage rate, it can quickly locate the fault and reduce the downtime (such as cylinder gasket damage, leakage test can locate the problem within 10 minutes).

 

(4) Tester operating advantages and design details

Visual leak rate reading: The pressure gauge directly displays the air pressure attenuation ratio in the cylinder, and some digital testers can display the leak percentage in real time (such as "leak rate 25%").

 

Multi-specification joint adaptation: Equipped with spark plug threaded joints of different size (such as 14mm, 18mm) to adapt to gasoline engines, diesel engines and engines with different displacement.

 

Assisted auscultation positioning: During leak testing, accurately determine the leaking component by listening to the location of the leaking sound through the stethoscope or ears (such as intake manifold, exhaust pipe, oil port, coolant pot).

 

 

 

3. Extended value: preventive maintenance and life assessment

Regular leak testing: Conduct leak testing every 50,000 kilometers for high-mileage engines (such as exceeding 200,000 kilometers) to detect progressive wear of piston rings and valves in advance (such as the leak rate increases by 5% every year, prompting maintenance).

 

Fuel economy analysis: A decrease in cylinder tightness will lead to a decrease in fuel efficiency (for every 10% increase in leakage rate, fuel consumption may increase by 5%), and economy can be restored through test optimization.

 

 

 

4. Precautions and testing standards

Test conditions: The engine must be in a heat engine state (water temperature above 80℃) to avoid the viscosity of the oil in the cold cylinder state affecting the sealing results.

Normal leak rate reference:

Gasoline engine: Cold engine state ≤20%, hot engine state ≤10%;

Diesel engine: Cold engine state ≤15%, hot engine state ≤8%;

High-performance engine: ≤5%.

 

 

 

 

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