Engine Pressure Drop Tester for Gasoline and Diesel Engines

Frequently Asked Questions About Engine Pressure Loss Testing

An engine pressure leak test addresses a different diagnostic issue than a compression test: It not only evaluates the pressure build-up in the cylinder, but also specifically introduces compressed air into the combustion chamber to check for pressure leaks. To obtain reliable results, the correct piston position, a leak-tight test adapter, and a reproducible test procedure are crucial.

• What is an engine pressure drop test?

  During an engine pressure leak test, a cylinder is pressurized from the outside with a controlled flow of compressed air.

  This test determines how much pressure escapes from the sealed combustion chamber.

  In addition, it is possible to determine the area through which the introduced air escapes.

  This makes the procedure particularly suitable for further diagnosis following an abnormal compression pressure test.

• What is the difference between a compression test and a pressure loss test?

  In a compression test, the engine itself generates the pressure to be measured during the cranking process.

  In contrast, the engine is not needed to generate pressure during the engine pressure leak test. The respective cylinder is moved into the required position and then pressurized in a controlled manner using shop compressed air.

  In simple terms:

  • Compression test: How well does the cylinder build up pressure?
  • Pressure leak test: How much pressure does the cylinder lose, and where is the air escaping?

  The two methods complement each other.

• When is it advisable to perform an engine pressure loss test?

  A pressure loss test may be particularly useful in the following cases:

  • abnormal compression readings
  • inconsistent compression values
  • loss of power
  • rough engine operation
  • misfires
  • increased oil consumption
  • suspected mechanical leak
  • inspection following an engine repair.

  The specific test required depends on the actual symptoms.

• Should compression or pressure loss be checked first?

  Often, compression testers are used first to determine whether there are any abnormalities between the individual cylinders.

  If, for example, one cylinder shows significantly lower compression, a pressure loss test can then be used to further narrow down the problem.

  However, depending on the diagnostic task, a pressure loss test may also be useful even without a prior compression measurement.

• How does an engine pressure loss tester work?

  The tester is connected to the workshop’s compressed air supply.
  
  The tester is calibrated using a pressure regulating valve. The cylinder to be tested is then connected to the tester using a suitable adapter.
  
  Leitenberger DRV-05 units feature a special pressure gauge for direct assessment of pressure loss. Analog systems include a green zone for quick evaluation.

• How is the pressure drop displayed?

  On the classic DRV 05, the pressure is displayed via a precision pressure gauge.
  
  The pressure gauge has a marked scale that makes it easier to assess pressure loss.
  
  On the DRV 05_BT, measurements are recorded digitally and the values are transmitted via Bluetooth to the LR Smart Tools app.

• Does a reading outside the green range automatically mean engine damage?

  No.

  In Leitenberger DRV systems, the green zone facilitates a quick assessment of the measured pressure loss.

  For conventional devices, the manufacturer specifies a setting of approximately 23%. However, this value should not be interpreted as a universally applicable threshold for every internal combustion engine.

  The final evaluation must be based on:

  • Manufacturer specifications
  • Engine configuration
  • Test conditions
  • Comparison of the cylinders
• What can you tell from the way the air comes out?

  The point where the introduced compressed air escapes can provide important clues about the affected area.

  Depending on the engine and test setup, air may be detected, for example:

  • in the intake area
  • in the exhaust system
  • at the crankcase
  • in the cooling system
  • at adjacent cylinders.

  The observations must then be compared with the specific engine’s configuration.

• What does “air leak in the intake system” mean?

  If air escapes toward the intake tract during the pressure loss test, this may indicate a leak in the area of the intake valve or its seat.
  
  However, the diagnosis should be made taking into account valve position, valve timing, and engine configuration.

• What does “air leaking from the exhaust” mean?

  If the air leak is clearly audible or detectable in the exhaust system, this may indicate a leak in the area of the exhaust valve or valve seat.
  
  Here, too, the valve position and engine design must be taken into account.

• What does “air leakage toward the crankcase” mean?

  Air leakage into the crankcase may indicate a problem with:

  • piston rings
  • piston
  • cylinder bore

  A certain amount of gas leakage is possible due to the design of the engine. Therefore, the assessment should not be based solely on the noise.

  For further diagnosis, crankcase pressure and blow-by meters can be used.

• Can a pressure loss test detect worn piston rings?

  The test can provide indications of increased leakage between the combustion chamber and the crankcase.

  This allows for a closer focus on the piston rings or the cylinder.

  However, it is not always possible to draw a definitive conclusion based solely on an air noise.

  Additional information can be provided, for example, by:

  • compression testing
  • blow-by volume measurement
  • crankcase pressure measurement
  • further mechanical inspections.
• Is it possible to detect a leaky cylinder head gasket?

  A cylinder head gasket can be a possible cause of pressure loss.

  Depending on the symptoms, air bubbles or signs of pressure may appear in the cooling system, or a connection to an adjacent cylinder may occur.

  However, a pressure loss test alone does not conclusively prove a defective cylinder head gasket in every case.

  If a connection between the combustion chamber and the cooling system is suspected, a CO₂ leak tester for the cylinder head and cylinder head gasket can also be used.

• What does “air leakage in an adjacent cylinder” mean?

  In certain engine designs, air escaping toward an adjacent cylinder may indicate an internal connection between the combustion chambers.
  
  Possible causes must then be further investigated based on the engine’s design.

• Does the piston have to be at top dead center during the pressure loss test?

  The cylinder to be tested must be positioned so that the valves required for the test are closed.
  
  In many test procedures, the top dead center of the compression stroke is used for this purpose.
  
  The exact procedure depends on the engine and the manufacturer's specifications.

• Why is the compression stroke important?

  A piston also reaches top dead center between the exhaust and intake strokes.
  
  In this position, however, the valves may be in a position that is unsuitable for the pressure loss test.
  
  For the pressure loss test, therefore, the relevant position is the one in which the combustion chamber can be tested with the valves closed.

• What happens if the piston isn't positioned correctly?

  If compressed air is introduced while a valve is open, the air escapes through that channel.
  
  This would indicate a significant pressure loss, even though there isn’t necessarily a mechanical leak.
  
  In addition, the introduced compressed air can act on the piston and move the crankshaft.
  
  That is why the correct engine position is particularly important.

• Can the motor rotate when compressed air is supplied?

  Yes.
  
  The compressed air exerts force on the piston.
  
  If the crankshaft is not securely held in its intended position, it may move.
  
  Therefore, the inspection must be performed in accordance with the prescribed safety and manufacturer specifications.

• How do you find the top dead center?

  Leitenberger offers special TDC adjustment tools for this purpose.

  The OT 01 detects top dead center via an audible signal.

  The OT 04 uses a piston inside a transparent Plexiglas cylinder with corresponding markings. Both systems can be used with adapters for the pressure loss tester and are designed for gasoline and diesel engines.

• What is the difference between OT 01 and OT 04?

  OT 01

  • Acoustic OT detection
  • for gasoline and diesel engines
  • For use with the pressure loss tester’s adapters.

  OT 04

  • Optical indicator
  • Plexiglas cylinder with movable piston and markings
  • 1-meter test hose with quick-connect coupling
  • Also for gasoline and diesel engines.
• Can the same adapter be used for OT adjustment and pressure drop testing?

  Yes, if the Leitenberger adapters are designed accordingly.
  
  OT 01 and OT 04 are specifically intended for use with the adapters for the pressure loss tester.
  
  This allows the OT to be determined first, and then the pressure loss test to be performed using the same or a suitable combustion chamber connection.

• What adapter is needed for a pressure loss test?

  That depends on the engine.

  Access to the combustion chamber can be gained, for example, via:

  • spark plug threads in gasoline engines
  • glow plug threads in diesel engines
  • injector mounts in diesel engines.

  The threads, length, and sealing surface vary depending on the engine.

  That is why a comprehensive range of adapters is available for compression pressure and engine pressure loss testers.

• Is there a universal adapter that works with all motors?

  No.
  
  A single adapter cannot accommodate all spark plug, glow plug, and injector geometries.
  
  However, flexible multi-brand adapter sets are available for commonly used spark plug threads.
  
  For example, the KPA Flex Set 02 contains five 200-mm-long adapters for M8x1, M10x1, M12x1.25, M14x1.25, and M18x1.5.

• Can the compression pressure adapters also be used for the pressure loss test?

  Many Leitenberger adapters are designed for use with both compression pressure and engine pressure loss devices.
  
  This is particularly useful in multi-brand repair shops, because the same engine-specific adapter lineup can be used for various mechanical diagnostic procedures.

• What is DRV 05?

  The DRV 05 is the classic Leitenberger analog engine pressure loss tester.

  Its features include:

  • Pressure regulating valve
  • NG 80 precision pressure gauge
  • Rubber protective cap
  • 1-meter-long test hose
  • Quick-connect coupling
  • Standard adapter ZKS 01.1 for M14x1.25 and M18x1.5.

  With additional adapters, the system can be expanded for use with gasoline and diesel engines.

• What is the difference between DRV 05 and DRV 06?

  The DRV 06 is based on the same basic pressure loss test method but also features a second pressure gauge for measuring the inlet pressure.

  This additional pressure gauge:

  • NG 50
  • Measuring range: 0–16 bar

  allows for direct monitoring of the applied inlet pressure.

• When is DRV 06 appropriate?

  The DRV 06 is useful when, in addition to the actual pressure loss reading, the inlet pressure at the device also needs to be monitored directly.
  
  This allows the user to view both values on the test device during the test.

• What is the DRV 05_Otto Set?

  The DRV 05_Otto Set is a test kit specifically designed for gasoline engines.

  In addition to the pressure loss tester, the set includes adapters for various spark plug threads, including:

  • M10x1
  • M12x1.25
  • M14x1.25
  • M18x1.5

  With additional adapters, the test unit can also be expanded for use with diesel engines.

• Is there an engine pressure loss tester specifically designed for motorcycles?

  Yes.

  DRV 05.3 is a special kit designed for motorcycles.

  In addition to the standard adapter, the package includes special long motorcycle adapters:

  • M12x1.25
  • M10x1.

  With additional adapters, this tester can also be used for other gasoline and diesel engines.

• Are there vehicle-specific pressure loss test kits?

  Yes.

  Among other things, Leitenberger offers special kit configurations for:

  • Ford
  • Kia

  as well as custom designs.

  The main difference from the base unit lies primarily in the specific set of adapters included in each configuration.

• What is the advantage of a vehicle-specific kit?

  Users are provided with a selection of adapters that are already tailored to the intended vehicle or engine applications.
  
  This reduces the need to first assemble the appropriate individual adapters separately.
  
  It is still possible to expand the system later with additional adapters.

• Is there a device that tests both compression and engine pressure loss at the same time?

  Yes.

  The DRV 05_BT Compression and Engine Pressure Loss Tester combines both diagnostic methods in a single digital system.

  In addition, the DRV-KP-Kit 01 is a classic kit that includes both a DRV-05 pressure loss tester and a KP-80 compression tester.

• What is the DRV-KP Kit 01?

  DRV-KP-Kit 01 Combination Set:

  • DRV 05 Engine Pressure Loss Tester
  • KP 80 Compression Pressure Tester 0–40 bar
  • Test hose
  • Various flexible gasoline engine adapters
  • Carrying case.

  This allows compression measurements and subsequent pressure loss tests to be performed using a single workshop kit.

• What is DRV 05_BT?

  DRV 05_BT is a digital compression and engine pressure loss tester with Bluetooth connectivity.

  The system enables:

  • Compression pressure measurement
  • Engine pressure loss measurement
  • Live transmission of measurement data
  • Graphical analysis
  • Data storage
  • PDF documentation
  • Sharing of measurement results.

  The data is displayed on a smartphone or tablet via the LR Smart Tools app.

• Does the DRV 05_BT require a separate display device?

  The DRV 05_BT does not have a built-in display for compression measurements.
  
  The data is transmitted via Bluetooth to a compatible mobile device, where it is displayed using the LR Smart Tools app.

• What is the range of the Bluetooth connection?

  Leitenberger specifies a data transmission range of approximately 15 meters for the DRV 05_BT.

  The actual range may be affected by the surrounding environment.

• Can the pressure loss test be documented using DRV 05_BT?

  Yes.

  The LR Smart Tools app allows you to, among other things:

  • view graphical representations
  • save data
  • create PDF documentation
  • share measurement results.

  This can be particularly helpful for workshop documentation and customer communication.

• Are the combustion chamber adapters included with the DRV 05_BT?

  No.

  Leitenberger expressly points out that the compression pressure/combustion chamber adapters for the DRV 05_BT are not included.

  The appropriate adapter must therefore be selected based on the engine to be tested.

• Is the DRV 05_BT compatible with the existing Leitenberger adapters?

  Yes.
  
  Leitenberger describes the DRV 05_BT as compatible with all of its own corresponding adapters as well as many other adapters available on the market.
  
  This means that, under certain circumstances, an existing set of adapters can continue to be used.

• Does an engine pressure drop tester require compressed air from a workshop?

  Yes.
  
  The standard DRV testers are connected to the workshop's compressed air supply.
  
  The external compressed air is needed to apply controlled pressure to the combustion chamber.

• Is any compressor, regardless of pressure, suitable?

  No.
  
  The compressed air connection and the test procedure must comply with the requirements of the test device being used.
  
  The inlet pressure is monitored on the device or adjusted via the pressure regulating valve for the test.
  
  With the DRV 06, the inlet pressure can also be monitored directly using the separate 0–16-bar pressure gauge.

• Does the engine have to be running for the pressure loss test?

  No.

  The cylinder in question is mechanically positioned in the required position for the test.

  Compressed air is then supplied from the outside via the test adapter.

  This distinguishes the test significantly from compression pressure measurement, in which the engine is cranked using the starter.

• Does the engine need to be warm?

  The required test conditions depend on the specific engine manufacturer.
  
  Temperature and component clearance can affect the results.
  
  Therefore, pressure loss values should only be evaluated and compared under the conditions specified for the respective engine.

• Should all cylinders be inspected?

  To obtain a meaningful assessment of the engine, it is often helpful to compare several or all of the cylinders.
  
  This makes it possible to determine whether a single cylinder stands out from the others.
  
  The specific procedure depends on the fault pattern and the manufacturer’s specifications.

• Do all cylinders have to have the same pressure drop?

  It doesn't have to be exactly the same one.

  The following factors are crucial:

  • Manufacturer specifications
  • Absolute pressure loss values
  • Differences between the cylinders
  • Location of the air leak
  • Test conditions.

  A universal threshold for all internal combustion engines would therefore not be practical.

• Can an engine experience a noticeable loss of pressure despite having good compression?

  The two methods evaluate the engine under different conditions.
  
  Therefore, compression and pressure loss tests may yield different additional information.
  
  If the symptoms and compression measurements do not clearly match, a pressure loss test may still be worthwhile.

• Can a pressure loss test replace electronic engine diagnostics?

  No.

  An electronic diagnostic test, for example, provides information on:

  • Error codes
  • Misfires
  • Fuel injection
  • Ignition
  • Sensors
  • Actuators.

  The pressure loss test, on the other hand, checks the mechanical integrity of the combustion chamber.

  Both types of diagnostics complement each other.

• What tests might be appropriate to perform after an abnormal pressure loss test?

  Depending on where the air is escaping and what symptoms are present, the following tests may be performed, for example:

  • Compression test
  • Crankcase pressure or blow-by measurement
  • CO₂ test of the cooling system
  • Endoscopy
  • Valve timing inspection
  • Additional mechanical engine inspections.
• What equipment is recommended for a professional pressure loss diagnosis?

  The following items may be useful for comprehensive workshop coverage:

  • Engine pressure loss tester
  • A sufficiently wide range of adapters
  • Top dead center (TDC) setting tool
  • Compression pressure tester
  • Digital Bluetooth system for documentation, if necessary
  • Crankcase pressure and blow-by meters for further diagnosis.

  You can find additional mechanical testing and service equipment under Testing, Diagnostic, and Service Equipment for Internal Combustion Engines.